Fundamentals of Physiological Psychology by Author Carlson, Neil R.

The most current, comprehensive, and teachable text for behavioral neuroscience.
Thoughtfully organized, Physiology of Behavior provides a scholarly yet accessible portrait of the dynamic interaction between biology and behavior. Close collaboration between the author and a talented artist has resulted in beautiful, accurate, and pedagogically effective illustrations in every chapter.

1. INTERNATIONAL EDITION

NEIL R. CARLSON

— Foundations ela
PHYSIOPO CI

2. Foundations of
Physiological
Psychology

University of Massachusetts, Amherst

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Library of Congres Cataloging Publication Data

Inclus bibliographical references and index
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4. in memory of
Paul Wayne Johnson

5. BRIEF CONTENTS

Origins of Physiological Psychology 1

Structure and Functions of Cells of the Nervous System 26

Structure of the Nervous System _ 61
Psychopharmacology 94

Methods and St of Research 122

Vision 154

Audition, the Body Senses, and the Chemical Senses 188

1
2
3
4
5
6
7
8

9 Reproductive Behavior 260

10 Emotion 292

Sleep and

iological Rhythms 226

19 and Memory 356

13 Human communication 398
14 neuro

15 schizophrenia, Afect

ial Disorders 432

isorders, and Anxiety Disorders 460

16 autistic Attention-Detici/Hyperativiy Stress, and Substance Abuse Disorders 495

6. Pre si

Origins of Physiological Psychology 1
(= PROLOGUE: Rens pation 2
Understanding Human Consciousness: A Physiological
‘Approach 3
Spl Brains 2
M INTERIM SUMMARY 5
The Nature of Physiological Psychology 6

INTERIM SUMMARY 10

ural Selection and Evaluation 10

ona Lange Brains 15
INTERIM SUMMARY 16.
Ethical Issues in Research with Animals 17
(Careers in Neuroscience 19)
INTERIM SUMMARY 20
Strategies for Learning. 21

Im EPILOGUE: Modes of Brain Functons 23
Key Concepts. 24

Suggested Readings 24
Suggested Web sites 24

Structure and Functions of Cells

of the Nervous System 26
Im PROLOGUE: Unesponsve Muscles 27

Cells of the Nervous System 28

The Boon ardor 85
neni SUMMARY. 35

Communication Within a Neuron $6

INTERIM SUMMARY 47
Communication Between Neurons 48

Action of Resp
Fenosa Rotel 51
Termination of Pos al 58

INTERIM SUMMARY 56

Im EPILOGUE: Myasthenia Gris 57
Key Concepts 59

Suggested Readings 59
Suggested Web sites 59

Structure of the Nervous System
(= PROLOGUE: The Let Gone 62

sof the Nervous System 62

7. INTERIM SUMMARY 6e
“The Central Nervous System 68

The Spinal Gnd 84

INTERIM SUMMARY 86
“The Peripheral Nervous System 86

= interim SUMMARY 91

Im EMLOGUE: Unie Nage 91
Key Concepts 92

Suggested Readings 93
Suggested Web Sites 53

ieee oe

Psychopharmacology 94
1 PROLOGUE: À Contariated Drug 95

Principles of Psychopharmacolog 95
Pharmacohineis 96

Drag
eto Repeated Administration 9
Pace Hts 100

INTERIM SUMMARY 101

Sites of Drug Action 101
ets on Proton of Neu

etn Storage and Reese of Neuotranniters M2
Yates on Receptors 103

INTERIM SUMMARY 105
[Neuroransmiters and Neuromodulators 105

Aine Acs US

Sole Gane 118
INTERIM SUMMARY 118

Im EPILOGUE: Helpful ots Hom a Fagedy 120
Key Concepts 120.

Suggested Readings 121
Suggested Web Sites 121

Methods and Strategies of Research 122
I PROLOGUE: Heart Repaired ran Damoged 123

as Damage
Produc Bin Lodons 125
iological Methods 128

Tracing Nowal Connections 130

INTERIM SUMMARY 136

Recording and Stimulating Neural Activity 135
yá Neural chi 196

Behan Elec Elia Bain Samui 144
= interim SUMMARY

[Neurochemical Methods 146

Finding Neuro That Produce Parla
"emochemicte

Lai Pair Receptor 148

INTERIM SUMMARY 149
Genetic Methods 150

option Satis 151
Tangeed Muatons 151

INTERIM SUMMARY 151

Im EPILOGUE: Wach the Bain Was 152
Key Concepts 152

Suggested Readings 153
Suggested Web Sites 153

8. Vision 154
Im PROLOGUE: Seong wih Hs Hands 155
‘The Sims 156

Anatomy ofthe Visual System 156

Photosceptrs 160

INTERIM SUMMARY 162

Coding of Visual Information in the Retina 163
Coding Cor

Anatomy ofthe Site Carte 168
Sata Frequency 170
Redon Dipari 17
Modular Organization ofthe Suite Cane

INTERIM SUMMARY 173

Analysis of Visual Information: Role of the Visual
“Associaton Cortex 173
‘Two Stream of Val Anh 173
Perpion af Calor

«pon of Moxement 180

ception of Spal Location 182
INTERIM SUMMARY 103
EPILOGUE: Case Studies 185
Key Concepts 186

Suggested Readings 186
Suggested Web sites 187

Audition, the Body Senses, and the
Chemical Senses 188

PROLOGUE: Alin Her Head? 189

Audition 189

Anatomy he Ear 190

INTERIM SUMMARY 202
Vestibular System 205

The Receptor Cll. 204
INTERIM SUMMARY _206
Somatosenses 206

Recopie Organs

erepion of Caancons Stimulation 208

INTERIM SUMMARY 213
m 214

Olfacton 219
The Sims 219
Informan 22

WINTERIM SUMMARY 222
1 CPILOGUE: Nawal Anales. 223
Key Concepts 224

Suggested Readings 225
Suggested Web sites 225

9. Sleep and Biological Rhythms 226
I PROLOGUE: Woking Nightmares 227
A Physiological and Behavioral Description
of Sleep 227
INTERIM SUMMARY 231
Disorders of Sleep 231

Nucokpy 2
REM Sleep Behr Dioner 254
Problems Asche with Sn Wine Sloop 25

2

Fancionsof Seine Sleep 236

Functions of REM Sleep 238
ETE
Physiological Mechanisms of Sleep and Waking 240

Neural Conta of Arnal 2
Neural Contra of le Soop 25
Neural Contato REM Sep 47

INTERIM SUMMARY 250

Biological Clocks 251

The Pinal Gland

Changes in Cain Rha Shi Work
PTE

INTERIM SUMMARY 257
18 EPLOGUE: funcions. Drums 258
Key Concepts. 258

Suggested Readings 259
Suggested Web sites 259

Reproductive Behavior 260
Im PROLOGUE: from Boy to Gil 261
Sexual Development 261

nee and Fico 26

er alongman comiaronse

Development ofthe Sex Organs 262
INTERIM suMMaRy 266
Hormonal Control of Sexual Behavior 268

Hormona Contra of Female Reproductive

CES
Hormonal Cont a Sxl Bear of

.
Neural Control of Sexual Behavior 261

INTERIM SUMMARY 280

aes
INTERIM SUMMARY 284

Parental Behavior 285
Merl Behavior of Raden 265

Neural Conta of Paternal Bio. 288
INTERIM SUMMARY 264

M EPILOGUE: From Boy 0 Gil and Back Again 289
Key Concepts 290

Suggested Readings 291

Suggested Web sites 291

ae AO sere

Emotion 292
18 PROLOGUE: tele and Emotion 293
Emotions as Response Patterns 295

Ager and Agres 26

Hormona Conta of Aggresive Behavior 308
INTERIM SUMMARY 307
Communication of Emotions 309

Facial Expresion of Emotions Innate Responses 909

‘Nera ass of the Communication
notions Recognition 310

10. evra i of the Communication of Emotion
aprenden SE

interim SUMMARY 316
Feelings of Emotions 316

The JmesLange Theory 316
INTERIM SUMMARY 318
M EMILOGUE: MV Revsted 318
Key Concepts 319

Suggested Readings 320
Suggested Web sites 320

eee

Ingestive Behavior 321
Im PROLOGUE: Not Her Faut? 322
Physiological Regulatory Mechanisms 329
Drinking 325

Some Facts About Fi Balance 325

Two Types

¡Neural Mechaniams of Tin 397
INTERIM SUMMARY 328
Est
INTERIM SUMMARY 332

What Starts Meal? 332

and Metabotism 329

Environment Factor 392

Psiloc Hunger Signal 333
INTERIM SUMMARY 334
What Stops Meal? 335,

Ler Factors 387

Sis During the ape Pane
Role of tin 397

‘Vong Ter Sate: Signal rom Apne

WINTERIM SUMMARY 338

Brain Mechanisms 339

INTERIM SUMMARY 344

Eating Disorders 545.
INTERIM SUMMARY 351

(= EPILOGUE: Treatment of Obesty 353
Key Concepts 354

Suggested Readings 354
Suggested Web Stes 355

Learning and Memory 356
IM PROLOGUE: Ever Days Alone 357

‘The Nature of Learning 357

INTERIM SUMMARY 361

Learning and Synaptic Plasticity 361

Induction of Lange Potentiation 362

INTERIM SUMMARY 370
Perceptual Learning. 371
INTERIM SUMMARY 373
Cnssical Conditioning 373
INTERIM SUMMARY 375
Instrumental Conditioning 375

Role of the Basal Gala. 375
INTERIM SUMMARY 381
Relational Learning. 361

man Anrograde Ars 382

Syed Learning Abies 38

Declare and Nolelaraine
Memories 345

Amer Amnesia: are a
elon Learning 380

Rote the of Hippocampal Formation
‘Spatial Memory 360

11. Rettional Learning Laboratory Ani

INTERIM SUMMARY 395

1 EPILOGUE: What, Esa Does the
Hippocampus Do? 396

Key Concepts 396

Suggested Readings 397

Suggested Web sites 397

Human Communication 398
= PROLOGUE: Can't er oros 399

‘Speech Production and Comprehension:
Brain Mechanisms 300

Speech Proc. 401

Speech Comprehension 405
The Bilingual rain AU
Prod Rhythm, Tone and Emplasisin Speech 416,
INTERIM SUMMARY 417
Disorders of Reading and Writing 419

Tora an Understanding ol Reding 1

Dach 1
INTERIM SUMMARY 428

IM EPILOGUE: Anahi of Speech Sounds 429
Key Concepts. 430

Suggested Readings 430
Suggested Web sites 431

Neurological Disorders 432
Im PROLOGUE: I Started wth HerFoot 433

Tumors 433

Seizure Disorders. 435

Cerebrovascular Accidents 438

INTERIM SUMMARY 440

rm ablongman con/aronte

Disorders of Development 441
INTERIM SUMMARY 444

Degenerative Disorders. 444
Tiana Spongi

Encephalopaies 4

ss

INTERIM SUMMARY 457
Im ENLOGUE: Secure Surgery 457
Key Concepts 458
Suggested Readings 458
Suggested Web sites 459

Schizophrenia, Affective
Disorders, and Anxiety Disorders 460
m PROLOGUE: Sue Cect 461

Schizophrenia 462
ei 463

Pharmacology of Schizophrenia: The Dopamine
spas 46

Schivopnenia asa Neurological Dioner 166,
‘interim SUMMARY 47
Major Affective Disorders 475

E INTERIM SUMMARY ans
Anxiety Disorders. 485

One Compuie Disorder 487

12. INTERIM summary 491
Im ERILOGUE: Tarde Djsineso 492
Key Concepts 493

Suggested Readings 493
Suggested Web sites 494

Autistic, Attention-Deficit/Hyperactivity,

Stress, and Substance Abuse Disorders 495

m PROLOGUE: À Sudden Can 496

INTERIM SUMMARY 500

AueionDefici Hyperactivity Disorders 300
Decio um

caes 301
Stress Disorders 502

= unten sumany_st0

Stance Abuse Disorder 811
Therapy for eg Nan 5

m Ten summany 527

= EroGuE: Cat Con ng

Key Cones 530

Segre eaings 520

Suggested web tes 520

References
Name Index

‘Subject Index

531
558
563

13. Uy Bie have wanted oho how sing work
Ar sm ae

tcresing pages 1 see wht vas ise. Much 1
are ee | ougre tat taba (ra kat gu be
Sil wh me Since my ole dys, Lave bee ty
to nd ou an aout 8

The a of
and produce one toda. A large number of seni
re ng to undersand the play of bear, se
an more here es Their ndings pride me
Var work an hank thes forging me someta
Sop. Without ther efforts 1 cou no hve rit

working of the most in

saroscience research i avery busy

Tote the fis edicion of thisbookst the request of
my colleagues who teach the cours, and who va
briefer version of Py

‘hiss on vecarch related to humans. The fist par of
this book i concerned wih Fondations the history of
the field, the structue and fat

roanatomny. pochopharmacology, a

da

a of Behavior with more ©

à methods of re

search, The second paris concerned wit
Sensory systems The third art deal ith what might be
Called “monated” behavior: ep, reproduction, emo»
tion, and ingestion, The fourth part deal with learning

on. The final part deals
‘sith neurological and mental disorders.

pus the

and with verbal communica

Content Changes

OF course al chaptes inthis book have been revise
My calleagues keep me busy by providing me within
teresting vescarch rests describe in my book. The
problem always to include the interesting new mater
{al without letting the length of the book get out of
land. Like he previous editions, thin edition co
chapter on neuological disorders which isnot ound lo
Physiol of Behavior

The following ls includes some of the
that new to ai citons

+ Funcional imaging studies on perception of form

plication of vibrations of the basar membrane

New research onthe presence of dorsal and vent

New research on the caps

Anockout mice

isons disease

The discovery that narcolepy ia neurodegenera
tive disease of hypocretinergic neurons

[New research on the role of adenosine a sleep
promoting chemical

New research on the effects of estradiol on women's
sent interest

Now research on the human amygdala and emo-
tional memory

New research on the role of the prefrontal cortex in
decision making and moral judgments

14. + The role of serotonin in functions of prefrontal
cortex relance to anger and aggresion

+ New research on the mechanisms of fongterm
potentiation and its roe in Learning

The rote o

place cells in spatial n

Funcional imaging studies of 1
ippocampus
+ A me section on the bilingual ba

The role of languages wth irregular orthography
inthe prevalence of developmental dislexia

Evidence for los of cerebral gray mater
schizophrenia

New research on the interactions between pre
frontal cortes ventral tegmental arca, and nl
accumbensin the development of chizophrenia

Evidence that depression may per
cis ofthe anmgdala and oxbitotrontl cortex
\Uspoactisiy ofthe subgenual prefrontal

Lack fa firm fae arca inthe brains o au
adults

Anew section on anemiondefici/hyperactvig
disorder

The role of increased sensiticio of brain lucocor.
postraumati tres dorer

ya

The role of basolateral asia con

iioned drug era

Evidence thatthe orbitofrontal cortex and ante:
rior eingulate cortex ae involved in drug casing

+ Evidence that stress earl in ie ca
cepuity to drug addiction

There are some in ences beiseen this
book and Physiology of Behavior The texto this hook i
not simply a shorter and denser version af its predoces.
sor. kept thellsatve examples, especially those del
ing with human disorders, and added explanations of
phenomena to be sre that students without am
ground in Biology could un

Although I have simplified some of the detailed expla
nations have retained the important principles.

Strategies for Learning

way that a research project might pro-
Each step illustrates particular procedure in he
st in which it would De applet in an ongoing,

+ Learning Objectives ach ch
learning objectives, which a
work forthe study guide that accompanies bisex
Prologue. A Prologue, which contain
tion of an episode nvoking
fran ie in newroxcience, opens cad
Epilogue. An Epilogue atthe end ofthe chapter re
solves the aus rated in the prologue, discs,
{hem in terms of what the reader has essa in the
chapter or introduces a related topic
Interim Summary follows each major section of the
book. They n nice wel ricas, but ao
break each chapter into manageable chunks
“Thought Questions follow mos interim summaries,
sont hat he

er begin with ist
serve acıhe frame:

edn the
the terms ae fist disused
Pronunciation guides or ter
ul to pronounce ae ae fo
+ Key Concepts. Each chapter ends with key com
cepas, which provide a quick review. Tit of Sug
iested Reading and Sopgested Web Stes provide
More information about the topics discussed in the
chapter.

Full-Color Art
The illustrations in this book were prepared by Jay
Alexander, of LHua Graphie Jay lo works in he Poy
‘ology Department at the Universi of Massachwet,
and he and I have heen working together om my books
for several year think the revit of ou collaboration

isa set of clea, consent, and attractive lation.

Strategies for Learning
‘Supplements

1 throughout the ook, was
uxilogical psychology o daly
lite, You wil find a Strategies for Learning” heading,
in Chapter 1, and a chapter entitled “Methods a
Strategies of Research,” This chapter docs no

à bewildering lis of rescarch methods
Reader ed through a st of hypo

1 have prepared a revised CDROM, which contains the
Neurmeienc Animations and the Compal Study Cie
“The animations demonstrate some ofthe mos importan
principles of neuroscience through mencment and imer
Action. The animations have been substantially revised
and expanded from the previous version, They include

cules on neurophysiology (Newral Communication,

15. The Action Potential, Smapnes and Postsmaptic Pen
ily, neursnatomy (The Rotatable Brain, Brin Slices,
and Meninges and CSB), pychopharmacolog, research

method, audio, memory and verbal communication
The modales on research methods include ihre new
videos demonstrating histo morado

raph and implantation of an intracranial can The
interactive Comput Sty Guide, accesible through
the same menu, contains à st of setests that include
mulpiechoice questions and an online review of terms
nd defini. The questions and ist of torm and de
tons present questions and keep track of your progres,
ied ems uni you ae anmered al of
y The computerize sty guide lo in-
race figures and disgramo from the book
‘hail ep student ear terms
ROM is included re withthe purchase ola ne book.

A Sandy Gide, which my wife and 1 wrote, is also
available
suing study behavior. It promotes a thorough under.
nding of the principles of plasiological psychology
through active participation hn the learning. proces.
The study guide contains a set of Concept Ca An im
portant part of learning about physiological pschology
FRacquiring new vocabulary, and he concept cards will
help with this tak. Terms are printed on one side of
these card, and definitions are printed on the other.
The publisher ofthis book, An & Bacon, boss
‘companion Web sie for thin ext: wwwcablongman.com/
‘arlonbe, This site contains additional mul
test questions for sudo ie by chapter
Forum allows you to further practice exam taking
Web sie alo provides hot
interes and tescarch updates, provided by
‘man, Professor of Psychology at Texas ARM

‘workbook provides a framework fo

soother relevant sites of
sul Well:

Supplements for Instructors

Several supplements are salable for instructor who
adopt this book

‘Instructor's Manual Wien by Bill Mei Indiana
University of Pennoyhania this is an excelent wol
for chat preparation and management, Each
shaper includes am At Glance Grid with detailed,

information king to other available
teaching objectives, lecture materia,

an a

‘of video, media, suggested ead

sources In addition, the

prehensive ix of student Rando

Test Bank. Writen by Paul We

University th cei

Ademonsrai ‘update st

rar abtengman comasanée

‘questions that target ey concepts Each chapter has
nclnding a

Halse, sort anse and esa, ach

sat stun jean, page references à fal
rating, and type designation, In addon the ap
pendi includes a sample opersbook quiz. This
products also availabe in TesiGen 53 computer.
Ac version, for une in creating tests he case

+ Powerpoint Presentation.
in the classroom, was created by Grant Me
Edinboro Univers of Pennsytania, Each
includes images from the textbook, wi
tdectroni

+ Transparencies for Physiological Pocholo; © 2005.
Completely updated. There are appr
fallcolor acetates to enhance classroom lecture
lcision, This package includes images
and Bacon's major phological picholog ext

+ Digital Media Archive for Physiological Psychology,
© 2004. This ia comprehensive source Tor video
and animation: text images, including charts,
‘raph, tables and figures: and PowerPoint lecture
Presentations all from Al and Bacon's major
Divsologial psychology texts I ia powerful took
for customized classroom presentation,

+ Physiological Psychology VideoWorkshop,Insruc-
Lors Teaching Guide. A CD ROM includes video
modules that offer many usc ideas
ing VideoWorkshop into your course
cludes correlation grids for individual physiological
pschology texts, nummaries foreach video hp.
Erica thinking questions, muliplechoice ques

answer key for he Staten
[CDROM and

appron
hie

inerte tol for we

‘ons web ink and a

Guide. For your reves th

Guide, ging you

one easy reference

+ CourseCompass. Powered by Blackboard, this
‘course management stem use powerfal tite of
took so insructors can create an online presence
For any course

1 complete program

In Conclusion

Trying to keep up with the rapid progress being made in
neurowience research poses challenge

nd vexthook writers Ha student simply memorizesuhat
we believe atthe time to be facts, he oF sed Ich wih
Anosledge that quick} becomes obwoet. In his book
Ihave ed to preside enough background material and

16. ‘enough knowlege of base physiological processes so
that the reader can revise what he or she las learned
‘when research pres us with new information,

Y designed this text to be interesting and informe
fe have endeavored to provide a solid foundation
further stds. Stents who will not take subsequent
‘oures in this or related fields should receive the at
faction ofa much beter understanding of thet cnn be

slave a greater appreciation forthe
i advances in medical practices related 10
disorders tha afecta person's perception, mood; or be-
havior | hope that people who carefully rad this book
ill henceforth perceive igh

nan behavior

Acknowledgements

Although must accept the lame fora
ofthe book, e

shortcomings

and Paul Wellman for his work on the test bank. an
{orthank colleagues ho helped me with the present ei
tion ofthis book and the latest edition of Pilg of Be
avi by sending reprints of their work, suggesting
topics that 1 should coser, sending photographs that
have been reproduced in this book, and pointing ou
deficiencies in the previous edition. thank the follow
ing reviewers for their comments on this ei

Adriana Alcantara, University of Texas at Ausin
Janis L. Anderson, U
John E Axchon, Holy Cros College
Norris R. Bancroft
Mark E Bas
1, Monmouth College

versity of New Mexico

Weber Sate University
of De

Metro State Colle

ao want o thank the people at Allyn and Bacon
Kelly May, my editor, provided aisance, support, and
‘encouragement, and Adam Whiter editorial sae
tant. who helped to gather comments and sggesions
from colleagues who have read the book. Erin Lid
lovers the production ofthe ancillary materia: study
vide, Animation CD-ROM,

structs mama, rae

parencies Videoworkshop, PowerPoint, and
inaschivc, Mary Beth Finch, the producto
sembled the team that designed and
book. Carol Somberg designed the book which looks
prety good, | think, Barbara Gracia, of Woodstock Dub-
lies Services, demonstrated her masterful skill or
‘managing the book's production. She got
Seryihing done on time, despite an extren
ew people realize what ii
and ime<onsaming job a production eitor as
ih project such as this with hundred filtration
and an author who tends to procrastinate, but do, and
Tihank her forallshe has done. Bashara Willette served
ascopy editor She gave mea chance to fix my errors be
fore anyone else saw them in prin
must alo thank my wife Mary for her support
isa lonely prt, because one must be alone
one’s thigh for many hours ofthe day. thank,
her for giving me the ime to read, reflect, and write
without cg hat was neglecting her too much

roduced the

To the Reader

"hope tha in reading his book yu wil come not only
to lean more about the bra

for the marvelous organ its
‘complex and perhaps the mos remarkable thing hat

our attempt to understand

‘While working om this book, imagined mel talk
ing wih students telling them interesting stories about
the findings of clinicians and research scientists, Imag
ining your presence made the tsk of writing a ite Less
lonely. 1 hope thatthe dialogue will continue. Please
ite to me and tll me what you ike and dike about
the book. My address Department of Psychology, Tor
in Hall, University of Masachusetts, Abert, Mass
huss 01003, My email address is rc umas ln
you write to me (or send me an eal), we can make
he conversation a wos exchange

NRC

17. Origins of Physiological ***
Psychology

18. René's Inspiration

Rent aloneyandieligentyoung gurgling of water but at fat coute operating the machine, He sent the
man ol eghteenyeors hadseduded naninginthedarknes AShiseyesbe- resto the aternoon wandering Cough
Pie in Saint-Germain, a Vilageto came acastomed 1 the gloom. he the tows stening 1 te muse ond
he et far He dc. couldmake outa figure umistedby beingentetined by the tes
fered nervous beokdoun and chose fikering tre. He approached the During his stayin Sim Geman,

the retreat to recone Even before com- figure, we soon recognized as at Ren wed the oy garde age
ing Saint Germain he Ra her of Ofaoung woman. Ashe drew dre and again He ad een thinking about

‘he fabulous royal garder but for” Resa ttes ul atrome therlaorhip been the move
Henri and Mare de Medi andone statue of Diana, bathing in apeotot mans animate and inaimateob-
Sunny ey he deeded to vs them. The water Suddenly he Grek gods ad jets uch had concerned papers
‘uardstppedhimatthe ate but andhidbeind bronze reiiuth As forsometimo. He thought hes the
han he denia Rane aa student René pursed her an imposing state of aparentypurporetl, ut obviously,
[tthe Kings school at La Fiche, hewas Neptune sein front im baring inanimate, movements ofthe status on
ero enter The gorerscon- hey with hs tient anse tome important question
ed ofa series of ge tec Rent wos delighted. Hehadheard bout the relationship between the
‘reooting te Si, planted inthe about the day oparstedme. mind andthe body. Even after he eft

Syria ere fin so loved by hankal ergarsand the moving Status, Saint-Germain, René Descartes ested
the French Grotteswerecutinto the buthehadnotexpeced such alm. As the grotoes in hs memory and he

limestone lid atthe end faster ha a bc tomarte entrance went ar to name M daughter
race René enteredoneofthen:He agro hess the platesburedin Francine after thew Geignen. the
hear eri mune acompenied bythe thegrund thtconvoledthewaher ann bother forn

Berner in ion perhaps herent ones ihn u. The
anal int we can pants, comple rinse, aed et

ding it arf all previous explorations our species has

One ofthe most universal of all human characteris is
to explain what makes things happen. In

ancient dines, people believed that natural phenomena wer

caused y animating spits A moving objec

wind and des, the sun, moon, and starswere assumed o,

euros We wm

Ihave spits that caused them to move. For example, tones
Fell ten they were dropped because their animating spirits
wanted to be reunited with Mother Earth, As our ancestors
became more sophisicated and learned more about mature
they abandoned thi approach (hich we cal anism) in
vor of physical explanations fr in 1 object.
Bat they ail wed spirits 10 explain human behavior:

From the earliest historical times, people have believed
that they passed something intangible that animated
{tema mind, a soul ora pi, This belie tens from the

fact that each of us is amare of bis or her own existence
When we thinkor act, we feel as though something inside us
is linking or deciding to act But what i the nature ofthe
human mind? We have physical bodies with muscles that

ox local pgs ar a by nd
Unsestand how we tink remember and and welleven perceive information about the world around us, Wi
‘teed he are four emm eaten bodies the nervous sem plas a central role recevin

19. Formation from the sensory ongans and comwrolingihe monements ofthe muscles
‘But what ithe mind, and what role doc play? Does contol he nervous system
Isita prt ofthe nervous syste? si physical and engi ie the es of the body,
a piri that il lc remain hidden?

Physiological psychologists take an empirical and practical approach to dhe study
‘of human nature, Most of ws believe that the mind ia phenomenon produced by
the aci ofthe nervous tem. We believe that once we understand the workings
ofthe human body-—in particular, the working of he nervous sptem—we will be
able so explain how we perceive, how we think, how we remember
Weil even be able to explain the nature of our own sclfawarenes. Of co
are ar fom understanding the workings ofthe nervous stem, so only
Uther dh bei jsi,

dy human consonnes Fis, lets define
€ ed to reer to variety of concepts, in
pe wakefulness, Ths, a rescarel box an experiment us

we make amd not
ue fat at e be

How ean physialogiel pychologits
‘our terms The word mime ean
lingo

anesthetized. By eminunes, Lam referring 0 somethi
re fan can tel others aboutour thoughts, perception

ies and feelings,
‘We know that brain

ange or drugs can profoundly affect consciousness. Be-
be altered by changes he struct or chemistry ofthe
Brain, we may hypothesize that consciousness physiological function, Jas as be
havior is We can even speculate about the origins ofthis selfawateness, Conscious
nes and the abit communicate seem to go hand in hand, Our specie, with i
d enormons capaci for learning, swell served by our

ability communicate: o expres intentions to one another and o make request
‘of one another. Verbal communication makes cooper
to establish ustomsand aso behavior, Perhaps
has given rs tothe phenomenon of consciousness. That is aur ability to send and
receive messges with other people enables us

‘other words, o think and to be aware of our own existence. (See Fig

‘complex socal structure a

D send and receive our own mee

welt)

Split Brains

Studies of humans who have undergo cular surgical procedure deman
strate dramatically how diconnecting pars ofthe brain hat are moved wit per
‘eptions from parts that are involved with verbal behavior ao disconnects them

the part ofthe brain involved in ve
bal behavior may be the ones responsible for comsiouaness.

The surgical procedure à one that as been used for people with very severe
psy tha canot be controled by drugs In these people, nerve cells in one side.
‘ofthe brain become oseractve, and the ner transmite o the ter ide
fof the brain by struct called the corpus callos. The corpus callosum large
bundle of nerve fibers that connect corresponding partsofoneside ofthe brain with
those ofthe other. Both side ofthe bran then emgoge in il act a
cach other, caning a generalized eplepic seizure. These seizures can occur man
times cach day, preventing the person from leading normal ie. Neurosurgeons

{rom consciousness, These results sus

comple uen on
at rom tn fr canon
one ing a he Human
Bono Acs eu

md

corpus cana corps ta

20. BI care 1: 0001304 sio Peony ‘worablongman comen

‘The split tain operation A “window” ha bee peras in
these of the ram 2 at we can sete corporal

lt in operation war.
Steger cso pe
AAA]
soto gnc
erben es

discovered that cutting the corpus callosum (he splicbrain
Operation) greatly reduced the frequency of the epileptic
Figure L2 shows drawing of pertion. We
sce the brain being iced down the mle rom front to back,
dividing tint lso syunetial hades, À window” has been
an se the cor

special baie

pus cllosum being ©
(See Figure 1.2)
‘Sperry (1966 and Gazzaniga and his sches (Garang
1970:Gazzaniga and LeDous, 1078) have studied these patients
extensive; The largest par of the brain consists af two san
‘metrical parts, called the cerebral hemispheres, which receive
sensor information from the apposite sides ofthe body, They
Io control monementsofthe opposite sides. The corpus callo
Sum enables he two hemispheres o share information o that
ich side knows what the other sides perceiving and doing, A
ter the splitbrain operations performed the tuo hen
are diconnected and operate independent. Their sensory
‘mechanisms, memories, and motor Sistem can no longer ex
change information. Theeffecsof these disconnections are not
‘obvious tothe casual observer, forthe simple reason that only
One hemisphere—in most people the lell—contols speech
The right hemisphere ofan pilet person with à spit rain
appears to beable o understand verbal instructions reasonably
vell bat its incapable of producing spec
‘ome side ofthe brain can alk about what ii experiencing, pco-
ple who speak with a person with split brain are conversing with only one hemi
phere: the left. The operations ofthe right hemisphere are more difficult to detect
Even the patents eft hemisphere has earn about he independent existence of
the right hemisphere One of the fist things that these patients Sy they notice aller
the operation i hat une a mind ofits own.” For example
pa ing down a ok held ie let hand, even i they
Have been reading i it occurs cause the
sphere, which controls he left hand, cannot read and therefore finds the book bor
prise themselves by making obscene gestures
intended o. A pchologit once reported
mpd o heat hi wie with ene hand amd pro-
tect her with the other Did he rly want to hurt her? Ve ad no, ques
‘One exception tothe erased representation of sensry information is the of
factory sytem: That Es when a person snif fewer dhrough the
the left brain receive a sensation ofthe odor, Thus i the right wou
‘with split brain is closed, leaving only

Beeaseo

ofa patient
left noni open, the patient wil be able
1 odorsare (Gordon and Sperry, 1969). However the adore
patent wil oy that he or she sms nothing Bu, in Fact, the
fas perceived the odor and am demi. To show tha this iso. we ask
the patient to nel an odor wich the right oti and then reac for some objets
that ate hidden from view by partition, I asked o use the et hand, controle by

the hemisphere that de nel the patent wil elect he object that corre
sponds to the ador—a plate flower fra floral dor, a toy fh for fh odor, a
model ee forthe odor alpine, and so forth But asked to use the right hand, the

fais the test because the righthand is connected
id not smell the odor. (See Figure 13),

The effects ol cuning the corpus callos reinforce the conclusion that we be
‘come conscious of something only information about itis abe o reach the parts

othe Felt hemisphere,

21. Undestndng Human Corscsnes: patos! pose EHE

ent ofa jc n sponse 1 an lato simul by pan wth à
soit in

tion docs not reach the consciousness associated with these
sll know very le about the physiology of consciousness, but studies of people with
brain damage are beginning provide us with some usefulisights. This ates die
sve in later chapter,

INTERIM SUMMARY

Understanding Human Consciousness: A Psychological Approach
‘The concept of he mind has bee wth us fra on time probably fom the ares his
tory of aur spec Modem cenc has adopted a Dei! tat he word const of mater
and energy and that what we cl he mind canbe explained y the sae loa tat gor
lıner natural phenomena Sais ofthe funcions oft human merous ster tend to
Support poston athe ape sample of he spt bain shows rin mage, by di
‘Connecting bain functor rom the pement Pare, reveal hat
{he mind does not have dc aces ta ban encon.

Ven sensor formation abou à para bets presets othe ight emi
sober ofa peon who has hada pira operation the person snot are ofthe D.
but an seres, date by movements fhe ft hand that he et as een
parce. phenomenon suggests at conos ive operation othe veta
rectas o ef Respecte: maybe nrg pa mate ol
tu “aking to curves" Tha one we understand he angoge frei of the ba
sre may have one along way to undentanding how te bra con be ons of ou

22. BI 11° TER +: nono Prog Psychology

THOUGHT QUESTIONS.

1. Coulda sufiienty age and complex computer ever be programmed o be aware
‘of sel? Suppose that someone someday cars o have done jut that, What kind
‘of evidence would you need to prov or prove this com?

2. Clay the aft Nemisphre of à Person with a pt bran concious ofthe infor
mation receives and of ts own thoughts. Int concious ofthe mental
process of the right hemiphere, Bu pombe that the right empha icon
ous too, but jut unable to tak tou? How could we posi nd out whether

it 7 Do you see some similar

ete this ie aná th one ae inthe st

The mode
who have

‘ogy and Have applied them to the ie that concer al prychol
Ihave studied perceptal process, control of movement, ep and waking te
crie belerors emotional belantors, learning and language
An recent year we have begun to study the plsiology of h
nd mental disorder

ions such es ici

hoc of psychology with rc of physio
Ss Thun, we

The Goals of Research

The goal of al sent sw

plain the phenomena they study. Bat what do we

can by expen? Scientific explanation takes two forms: gencraliation and rede

tion, Most psychologie de
‘of havior as examples of general lis, which they deduce fr
For instance, most pschoogiss would cxpli
sam example ofa particular form of learning called dsl conditioning P
bik the person was Frightened cari in ie by à dog

of the animal perhapsthe person vas knocked domn by

pare with the sig

vith generalization. The explain particular instances

their experiments
pathologically strong fear of dog

Uerant dog or was auackex by a vicio one), and the subsequent sight of dogs
‘evokes the earlier response: fear

Mont physiologists deal with reduction.
terms of simpler ones, For example, they may explain the movement

hey explain complex plc

a muscle in
terms of he changes inthe membranes of muscle
cular chemicals andthe in

ecules within these

ar biologia would ex
forces that bind var

cell the entry of pa
teractions among protein m
cells By contrast, a molec

Plain these event in terms o
‘bus molecules together and cause various pars of
the molecules to be attracted to one another. In

tur, the job of an atomic physical o describe
mater and energy themselves and to account for
the various forces found in nature, Praciioners of

‘cach branch of science use red on sets

8 more elementary generalizations to explain the
phenomena ep od

The task of the physiolo
explain behavior in philo
Hogical psyetologists cannot sim
tis not enough to observe behaviors and core
them with piyioloieal

cal pychotogin ito
alters Bat physi
y be reductionist,

ents that occur atthe

23. The Nature of PysclogKal Psycnoiooy MERE

nical behaviors may occur or different reasons and thus may be in
Therefore, we must understand psy
avor occurs before we can tnderstand what

tinted by diferent physiological mecha
ological” why à particular b
ysilogical events made it occur
Let me proie a specific example Mic, He many other mammals often build
nest Behavioral observations sow tha mice wil ld nests under two conditions
en the air temperature is low and when the animal is pregnant. A nonpregnant
mouse will build a nest only if the weather is cool, whereas a pregnant monse wll
ui one regarde of the temperature, The same behavior occur fr diferen re
sons. In fact, nesthuilding behavior à controlled by two different physiological
‘mechanisms. Nest building can be studied a a behavior related to the process of
re context of parental behavior

tie, the research fort ot physiological pchologis involve bo forms
of explanation: generalization and reduction Ideas for experiments ae simulated
bythe investigators knowledge bath of pychological generalizations about beh
ior and of physiological mechanisms. A goad physiological psychologist must there
fore be both a good pachologist anda good physiologist

Biological Roots of Physiological Psychology

Study of (or speelatons about) the physiology of bchnior has ts root in aqui
Because is movement i necessity for ie, and because emotions cause to beat
more strong, many ancient cu the Egyptian, Indian, and Chinese
«considered the heat to be the eat of thought and emotions. The ancient Greeks
‘i too, but Hippocrates (400-370 6.) concluded that his ole shoul be assigned.
tothe brain

Not all ancient Greck scholars agreed with Hipporrates, Arise did not
‘hong the brain served o cout the passions of dhe heat. But Galen (10, 130-200)
‘sho had the greatest respect for Ariane, concluded that Aristotle's role for the
Drain was “utterly absurd, since in that cae Nature would not have placed the
(ephalon [bran] o far rom the heart, and she woul not have

Sensors nerves) to (Gale, 1968 transla
brain vo diseet and study Ae rai
igs. cts dogs. weasels, monkeys ana apes (Finger, 199.

‘René Descartes, a seventeenth-centiry French philosophe and mathematician,
as been called the father of modern philosop Although he an ot biologi, his
specilationsabont the roles ofthe mind and brain ithe control of behavior preside
“god starting point inthe history o physiological psychology: Descartes assed
{he world waa purch mechanical entity that, once having hen et in motion by God.
‘an is course without divine interference, Thus, to understand the world, one had
‘nls to understand how it ws constricted, To Descartes a
‘ces: their behavior was controlled by environmental súmul His iw ofthe human
bods was much the sme: as a machine, As Descartes observed, sone movements

human body were automate and involuntary. For example, ia persons finger
touched a hot object the arm would immediatly withdraw from the source of generation ect eke
lation, Reactions Ike this did not require participation ofthe mind: they occured ate | en roue cocino
‘omatially. Descartes called these ations reflexes (om the Latin flor, o bend | Bon man ebensions ot
Pack upon isl). Energy coming rom dhe outside source would be reflected back | 2" From
‘hough the nervoussystem to the muscles, which would contract. The term isin | reduction Toe sert

were mechanical de

we tr: but of coune we explain he operation ofa ee ferent nen pheromone
ike most philosophers his time, Descartes was dais he believe anne
person possesses a m tribe that isnot subject to =“

‘Of the universe. But his thinking differed rom hat of his predecesor in one im
portant way: He was the fist to suggest that ink exis tween the I
And is purely physical housing. the brain. He belived

tee an ata yd
mind | Moment prices ae rect
m

24. BE NT Phony ‘worablongman convenía

Figures ements wie the ty og ise
cs pies vea wih informotin abona vb
‘ata rom be ninety Reve Dares be RZ happening i the environment. I particular, he spot
a il care sins crac aes place the pica body,
‘ne prada espro e mudo on De meda aamallorgan sated ontop of dc brain sem, buried be
Soto ate ey gar Ach ath the eter hemispheres etd that the brain
icone the ey ser vial fat o ba were contains hallo chambers (he el) that are led
ds cami te eal M Pet dede Mid, and poliza that ns Mid ie under
e nd merce ornate Presa histcor when she mind decides to perform

An action, tit the pineal body ina particular direction

ite jock causing id o How om.

muscles to inflate and move. (Sc Figure 1.4)
As mesa in the prologue. the young Rene Descartes
sas greatly impressed by the » te in the royal
‘gardens (Jaynes, 1970). These devices served as models
For Descartes in theorizing about how the body worked

he pressurized water ofthe moving statis was replaced

by presea Mid in the senile the pipes nee ie
placed ty nerves: the ender by muscles and nal
Hei aesby the pineal bc. Tir stats
ne ofthe times hata technological device waste
‘sa model for explaining how he nern siem work
inscenceamodis late ple sem that works
on known principles and able to doat ea some ofthe
things that move complex et can do For example,
hen scents dicvered that elements ofthe nervous
Stem communicate by means of letra impasse.
arche developed models ofthe bain based upon ce
phone sichboards and, more recent computers
Absract mode, which are compete) mathematical
ther proper, have ao been clope
Desire model we ci toe
philosophie speciation oul end experimen
tt fatal ott ng or ils trove at
Descartes as wrong. For example aig aa ase
teneur) physiologist, und that ce
af og ere cated contacto of the mice wo which tasche,
Contraction occurred even when the nerve and mise were detached rm the est
‘ofthe odo the aby dhe msc wc ai ofthe nerve send
mad Ansporn | eget the mio were charters ofthese as theme. Th the
ici | es eo inate mists by dieting prit hr the mer Gt
pre one comes | vais experien prompted thers to state nature ofthe menge tant by
Earn nain | the nerve and the meas y mich muscle contacted. Theres ofthese efor
{ere toan accumulation of knee an the phyla of behavior
decos etree re. | Oe the mos importan gues it the development of esperimenal physiol

Bt Mae erent | ogy yas Johannes Müller a ninetenth-centuy German phyilogis. See Figure 15.)

Scenes ty. | Miller waa foreflachocat of the application of experiment echnique to phe
‘cman mare ciao) | joto. Prevowa, the acts of mont natural cents were med to nero
desarro fea | and eco. Although these activi are ewer Müller td that major

arias in our understanding of e workings ofthe body would be chive nly
eines ev. | by experimental removing oF ling an organ, tating ti response to
soso | Vos chemical nd there al os how he ongan ro

A ii tothe awl ofthe phology of havior

Serer misc. | vas is doctrine of specie nerve energia. Miller abserved wat although all nerves
Kematen iger sauna | carry the same basic message an elect impulse, we percehe dhe messages of di

25. ferent nervesin diferent way. For example, messges cari bythe
‘opie nerves produce sensations of visual images, and those carrie by
the auditory nerves produce nation of sounds How can different
‘sensations ari from the same baie messi?

The answer that

messages occur in diferent channels. The

portion ofthe brain that recches mesage rom the optic eres in
texpretsthe ct asia stilton, even ifthe nerves are actually
stimulated mechanical. (Fr example, when we rub our eyes, we ee
lisis light) Because diferent parts ofthe brain rece messages
rom ferent nerves, dhe brn mus be functionally dived: Some
paris perform some functions, while ther parts perform others

Maller'sadvocicy of experimentation and the logical deductions
from his octrine of specific nerve energies set he stage for perform
ingexperiment rech on the brain, Indeed, Pers Hourens- nine.
teemlecentury French physiologist, did jue that. Flowrensremoned
varios pars animals’ brains ad observed their behanior. By seeing
‘what the animal could n longer o, he could infer une funcion ofthe
‘missing portion of the brain. This method is called experimental ab-
lation (rom the Latin laos, "carried sway"). lourens lama to
Have discovered the regions ofthe brain that control hear ate and
breathing, purpose monement and vl and auditory reflexes

‘Soon ater Flourens performed his experiments, Paul Broca, a
French surgeon, applied the principle of experimental ablation tothe human rain.
‘OF course, he id not intentionally remove parts of human brain to see how they

Ihe observed the behavior of people whose brains had been dan

aged by stokes. In 1861 he performed an autopsy on the brain of a man who had
had a stroke tha ested in the low ofthe ability to speak. Bros observations ed
him to conclude that a portion ofthe cerebral cortex on the left side of the bran
perform functions necessary for speech. (See Figure 1.6) Other physicians soon
‘brand evidence supporting his conclusions. As you vil earn in Chapter 18, the
‘control of speech isnot localized in a particular region ofthe brain, Indeed, speech
requires many diferent funcions, which ate organized throughout the brain
N
derstanding ofthe brain of both human and laboratory animal

As T mentioned earlier, Luigi Galan wed electricity vo demonstrate that mus
‘les contain the source ofthe energy that powers their conta
tions In 1870, German phiiologints Gustas Fritsch

omnes Male (1801-185,

Eden! SS LT
Hiei ne lc mimalao a olor understanding the

physiology of the brain. They applied weak electrical current to
the exponed surface of do brain and observed the effects of
the simulation. They found that simulation of different por
tions ofa specific region of the brain caused contraction of pe.
Cie muscles on the opposite side of the body. We no refer to
{his region as the primary motor ots, and we know that nerve
cells there communicate directly with those that cause
Contractions. We also know that other regions of
tmunicate with the primary motor cortex and i
avions For example, he region that Broca found necessary fr
speech communicates with, and control he portion ofthe pri
‘mary motor cortex that controls the muscles of the lips tongue
and throat, which we use o peak.

One ofthe mos brilliant contributors to nineicenthcentury
science wis the German physics and physologs Hermann von
Helmholtz Helmholtz devised mathematica formulation ofthe
law of conservation of energy, invented the ophthalmoscope
(sed 1 examine the retina of the eve), vie an portant and

Parto! eet eo he bra rated apre

Top

26. BEI carre 1: Os ot Physiologic! Pychology

influential theory of olor sion and color blind
many physiological process Athough Helmholtz had studied under Miler, he
‘opposed Miller's belie hat human organs are endowed with a vital wonmateril
Force that coordinates their operations, Helmbolt believed that al aspects of ps
‘ology ate mechanistic, subject to experimental investigation.
Helmholtz was also the fist scientist 10 attempt to measure the speed of com
“duction dough nerves. Scientists had previous believe that sch conduction as

intial othe conduction that occur in wires, Ali at approximately the speed

al conduction was more than

‘0 fect per second. This measurement proved that ne
a simple electrical message, as we vil see in Chapter 2
century developments in experimental physiology include many
om, such as sensitive amplifies to detect weak electrical signal
techniques to naze chemical changes within and between cells, an
Histological techniques o se cells and their consten. Because these develop»
ments belong tothe modern era, they are discussed in detal in aubnequent chapter

INTERIM SUMMARY
‘The Nature of Physiological Psychology

All sentis hope t eplin natural phenomena. In this context the term explanation has
‘so ask meaning: generalization and eduction, Genealiation efetstothedsifieation
‘of phenomena according to er exentalfeatores 20 tat genera ls an be formulated
For example, observing hat raviatioal tración seated o the mas two bodies and
to the distance between them helps to explain the movement of planet Reduction refers
{the description of phenomena in terms of more Da phykal processes. For example,
rautaion can be explained in terms of forces and subatomic pares

úPryslogcalpychologists ue both generalization and reduction to explain behavior.
In large part generalization us the traditional methods of psychology. Reduction explains
behavior interme of riega events within the body rimaih within the nervous ys
tem. Thus, phyologalpayenology bus upon the tradition of both experimental sy.
chology and experimental physiology

‘The physiological psychology of today rooted in important developments of the pst.
René Descartes proposed a model ofthe ran bated on yravicay activated statues. Hi
model stimulated observations that produced important discover, The resulto Galvani
‘experiments eventually led oan understanding ofthe nature of the mesage transmite
by nerves between the brain andthe sensory organ andthe muss, Mules doctrine of
secc nerve energies paved the way fr study ote functions of specific part ofthe brain
‘hough the methods of experimental ablation and electri! stimulation.

‘Twouswr QUESTIONS

1. tithe vale of studying the istry of physiological psychology Is a waste of

2, Suppo we studied jut the lates search nd ignored explanations tht we now
know tobe incotect Would we be pending our time more profitably or might we
mss someting?

Malle’ insistence tha biology must be an experimental science provided the star
ing pon for an important waitin, However, other biologists coninued to observe
las and think about what they a and some of then arrived at aluableconel

27. Sons. The mont important of
Figure 1.7) Darwin formulated the principles OÙ natural sde and
lrevoltionized bol

tion,

Functionalism and the Inheritance of Traits

Darwin’siheory emphasized that al ano actrices
structure, coloration, behasior—have functional significance, For
«example, their strong talons ad sharp beak permit cages to catch and
at prey. Most caterpillar that eat green lave arc hemschesgreen,and
int thei tal back
round. Mother mice comutruct nest which keep thei ofspring war
Wout of arm was: Obriouay, the behavior ef is not heiten
Tow an it be? What inherited ia brain that causes the behavior o 0€
cuts Thus, Darwin's theory gave rive to functional, a Die that
y fal fonctions. So, to un
chaos, we mus fit un-
dor accomplish, We must dherefore
1d someting about the n

thet color makes cu For bist see them a

characteris of ing organisms per
erstand the pisito

dentand what these be
under

studied so thatthe behavior can be seen in
To understand
should know what its functions av This principle just as tue foral
ing ong
‘when they designed them, whereas organise ate thereat fa long series of ec
dents. Thus. stl speaking we cannot ay that an physiological mechanisms of
“organes have à purge But they do have function and these we ant 10
determine, For example the forelimbs sown in Figure La adapted or different
ferent species of mammals (See Figure 18)
tional analivof an aap trait was demonstrated
in an experiment by Blest (1957), Certain species of mothsand tetes have spots

A good example of th

he workings ola complex piece of machinery, we. _ Tom imaRaam Ar

ruta Seton a stos A
se scents was Chale Darwin. See FGFS A

(roll restons lg) an ng
infor ario

Bones ofre) human.) bt (whale) og, Though he roces at

o

©

28. ‘ahem proce ya

iy pls ets

ys that resemble eyes—particulal the ees of predators
Such as ons (Sce Figure 1.3) These sects normall ely om

fae for protection: the backs af their wings, when Folded, are ol
fore ike the bark of rec. However, when a bird approaches, the
inseet’s wings Mp open, and the hidden eyexpots are suddenly dis
played The bird then tends to away rather than eat the insect.
Best performed an experiment to sce whether the cjespots on à
mont or ter wings really disturbed birds that se ther. He
placed mealworms on dllerent backgrounds and counted bo many
"ori the birds ate Indeed, when the worms were placed on aback
{rod that contained eyespots, the birds tended o avoid them,

Darwin formulated his theory of vol

nt explain the means
by which species acquired their adaptive characters. The comer.
Stone of this theory isthe principle of natural selection. Darwin

ote that members of a species were not all dential and that some
‘ofthe differences they €

ied were inherited by thei offspring I
an individuals characteris permit it to reproduce more wecese
filly some ofthe individual offspring wil inherit vorab char
acteristics and wll themselves produce more offipring. Asa resul
the characerisicswillhecome more prevalent in that species. He ob-
served that animal breeders were able to develop strains that pos
sessed. particular traits by mating together only animals that
posses the deste traits I arial sein, controlled by animal
breeders, could produce so many varieties of dogs, cat, and Inetock, perhaps nat
tl sation ele responsible for the development of species. Of coun, it was

the natural envionment not the hand ofthe animal breeder. that shaped the pro
‘es of evolution

Darwin and his fellow scientists knew nothing abone mechanism by which

the principle of natural selection works. fat the principles of molecular genet

ry Bey here is

ies were not diconered unl the middle of the twentieth cen

how the process works: Every sexually reproducing micellar organi consists

Tange number of ells each of which contains chromosomes. Chromosomes are
Tange, complex molecules that contain the recipes for producing the proteins that
fells nee to grow and xo perform their functions In essence, the chromosomes
contain the blueprinas for he

nsruction {thatthe embryologial development)
Sa particular member ofa particular species Ihe plansare altered, different or
anim produced

The pl
accident changes in the chro

altere: mutations occur from tte to time, Mutations are
roms of Sports or eggs that join together and
ight strike a chromo

anisms, For example, cosmic radiation

develop into new

Some in a cell ofan animals tes or vary thus producin
that animal's offspring: Most mutaions are deleterious: he oflspring either fais
Survive or sursnes with some sor of dic, (See Figure 1.10) However a small per
“enue uf mutations ae beneficial and confer a selective advantage to the organ
ism that possesses them. That the animal ls more He than other members ofits
species t ve long enough o rep

¡icon ofspring. Many different Kinds of traits can conter a selective antag: re

sistance toa particular sce, the abit to digest new kinds of fond, more effective
Neapons for defense or for procurement of prey and even a more atraetive ap
pearance to members ofthe opposite sex (ater al, one mus reproduce to pass on
nes chromosome)

Natural he waits that can be aleve! by mutations ate physical ones: cromo»
somes make protein, which affect the structure and chemistry of cell. But the 1
Jes of these physical alterations can be sce

in an animals behavior. Thus, the

process of natural selection can act on behavior indirect. For example, ia partic

29. alsacien nd votaron AE
inchangsin te brain ht cause sll GUA NNN,

Stimulus chat ia more iy to escape undetete wen mim Be sn col
à predator pas near This tendency males the animal dl eae
more ke to survive and produce offipring tna ping om Pads seco evetape bt ete se sed
genes ta fe generate ae peor

‘Other mutations are not immediately favorable, but be-
rey do not pat their possesors at diadvantage, they

e inherited by at Teast some member of the species. ares
‘Sul of thousands of sch mutations, he members ofa parc
Jar species posess a variety of genes and are all ar east
from one another. Variety a definite ad

Diterent environment provide optimal
erent Kil of organisms, When the emvion
ment changes, species must adaptor a the rskof becoming,
extinct. Home members of he species poses aso of
y them toa to

de ollpring will survive, and the

species will continue

Evolution of the Human Species

Ti rake means o develop gradually (rom the La

“to unroll). The process of evolucion sa gradual change
the structure and physiology of plant and animal species as ases of natural ee
tion, New species woke when organiuns develop novel characterises that can take
advantage of unexploited opportunities in the environment

The frst vertebrates to emerge rom the ca—some 560 millon ycarsago—nere
mphiians tn fact amphibians have not entirely left he sc; hy sil a hi gs

eater and the larvae that hate rom the
aus with airbreathing I first reptiles ap-
peared. Reptiles had a considerable adtantage over amphibians: Their eg, en

{tose in a shel jst porous enough o permit the developing embryo to breathe
ond be aid on and, Thus, rele could inhabit segons na from bodies of wa.
terand they could bury ther egg where predators would eles eh to id them,
Reptiles soon divided into thee fines the ann, he ancestors of today tres:
the ips the ancestors of anos birds, rar, croc, and sakes andthe
maps the ancestor of day m group of smapsido, the tempi,
Became the dominant land animal during the Permian period, Then, about 218
milion years ago, the end ofthe Permian period was marked by amass extinct
Dust from a catastrophic series of voanie eruptions in preseneday Siberia dark
ned the a, cooled the earth, and wiped out approximately 5 percent af al an.
‘mal species Among those that survived. vas a small rapid Known a. a
¿dni direct ancestor ofthe manna, which firs appeared about 20 mi
tion years ago. (See Figure LH)

Mamma and the other warm-blooded anima, bird) were oy a mes suc
cess for many milions of years Dinos ued and arate had remain ana
and inconspicuous to void the ag vario agile and voracious predators. Then
corte struck the Maan peninsula of presentday Mexico, producing cloud of
dust that destroyed many species, including he dinosaus Stal, octal mame | ersten à aa bro
‘al survived the cold and à y were equipped with insulin for and | Pest 2d yy o
mechanism for mai het body temperature The voi et by the exime | Dre ae on gee
ton of so man age herbivores and carats pred the opp

mals to expand into new ecological niches, and expand they di secon

became

30. IET carrer 1: 00900! Palo ooo rm atlongmn conven

tes volve The rt primates, ike the rst mammal, were small and preyed
¡Y col blood vertebrate such as Tizard and fogs. The had
à permitted them to

the eyes sn), which Facilita arboreal locomotion and the capture
hearing plant evolved, primates began o exploit this enengyrich
on ol color vision enabled them o easly distinguish

of prey. Ae fi
Source of food, and the et

The fis hominis (husnanlike apes) appeared in Aiea. They appeared notin
«lense tropical forests, but in drier woodlands andi the savanna—sastareasof gras
lands studded wich camps of trees and populate by large herbivorous animals and
the carnivores that preyed on ther. Our rating ancestors continued eat it,

31. ‘of course, but they evolved characteristics that enabled

übers as wel to unt and Ki
themselves against oer prea
‘hey made tools that could eased to hunt, produce
clothing, and constrict dwellings; they discovered the
‘many uses of re they domesticated dogs, which great
increased hei by vo hunt and helped war of attacks
by predators: and they developed the ability vo comm
ice symbolically by means of spoken wor

‘Our closest ving relaies—the only hominids be
sides ourselves who havesurvved—are the chimpanzees,
gorillas and orangutans. DNA analysis shows that genet
cal there is very ile difference between these four
species For example, humans and chimpanzees share
KA percent oftheir DNA, (See Figure 1.12).

“The fist homini 10 leave Afi di so around 1
million years ago. This species, Homo erat upright
man”) eattered across Europe and Ava, One branch of
Homo eetus appears to be the ancestor of Homa nea
deals. which inhabited Western Europe betwee
120,000 and 30.00 years ago. Neanderthal resemble
modern humans. They made tools out of stone an
and discovered the une of fre, Our own spec
Sapiens, evolved in East Arica around 100.00 years ago.
paru Africa, and out of Africa o Aia, Polynesia, Australia, Europe, and the Amer-
cas They encountered the Neandertals in Europe around 10.000ycars ago ando"
existed with them for approximately 1,000 years. Exentualy, the Neanderthals

‘appeared —perhaps trough interbreeding with Homo api, perhaps through
on far resources Scents have not fund evidence fr warlike confit be.
tween the two species,

Evolution of Large Brains

Humans posessed several characteristics tha enabled them to compete with other
species Their agile hands enabled them to make and we took, Their excellent color
vision helped hem to spot ripe fruit, game animal, and dangerous predators. Their
mastery of ire enabled them to cook food, prone warm, and fghten nocturna!
predators. Their upright posture and Dipedali made it possible for them w walk
long distances efficiently with their eye far nog Ion desc long die
tances acros the plains, Bipedalisn aso permitted took and food
sith them, which mean that they could br roots, and pieces of meat Buck
ro their ibe. Ther inguiic abi enabled them 0 combine the collective know
edge ofall the members ofthe wibe, o make plans, o pas information on 10 st
sequent generations and to form complex erations that established her ats
as the dominan species Al ofthese characteristics required lange brain

A large brain requires large skill and an upright posture mis the size of à
‘woman's birth canal, A newborn baby’s head is about as large as it ean be As it i
the birth of baby much more arduows than the birth of mammals with propor
tionally smaller heads, including those of our closest primate relatives. Because à

Baby’ brain is not large or complex enough to perform the physical and intelle
tual abilities am al, it must continue 1 grow after the baby born. In fact, all
‘mammals (and all birds, for that matter) require parental care or a period of time

hile the nervous stem develops. The act that yung mammal (an particular,
young humans) are guaranteed to be exposed to the adults wh care for them

Aan Maat e pez sra OA rang

eat

32. CHAPTER 1: Orgia! Peal Polo rv alongmanconiationse

means that a period of apprenticeship is posible, Con
que. he evolutionary process did not have to pro.
sa ne fhe han sl te gage eee a brain with specialized cits hat performed
on pue acu mora specialized tasks. Instead, it could simply produce a
‘much is change the mansa rom iro al. ger brain with an abundance of neural cie
‘onl be modified by experience. Adults would nourish
And protct their offspring and provide them wih the
shi they woul
Al vere necessary, of course (for example, those involved
in analing the complex sounds we use for speech), but
by and large, the rain i a general purpose, program
mable comp
What pes of genetic changes are require to pro-
duce a larger brain? This question wil be addresed i
nore deal in Chapter 3, but the most important pring
ple appears to hea swing ofthe process of maturation,
Slowing more time for growth. This phenomenon is
know as neoteny (ron led as “extended
sth’) The brains of newborn mammalsare larger shan
Ac of humana, relative wo their bodyweight. After birth
the bods grows proportionally Ester than the brain. How
‘ever the mature human head and brain retain some i
Fale character, including their disproportionate
sive, Figure 1.18 shows fetal and adult skulls of chin
‘the fea halls are
‘nore sir than those of the adult. The grid
sow the pattern of growth, indiating much Tess
Tans pone TERA A Mama EA Ang change in the human skull rom bir toadulthood, (See
Toscan 10 Boon Bad Serie cts 193. Figure 1.13)

Noten evolution of th man kl The sl of etl

Chimp es

ppanzees and humans. As you can se

imp at oran at

INTERIM SUMMARY

Natural Selection and Evolution

Danish o evn, ias area he concept otura selection, provided
kn important contusion to modern phpilega ychlogy. The theory ers hat we
‘Mut undead the funcions performed y an organ body paro y botar.
“Through random mutations changes in an india ere matral case diferent pro
{eis tobe produce, uh senti the aeration of Some yl character. the
“hangs confer a eee advantage on he india the new genes wl be anses
fo mor andre members the spec. Even Behaviors can era, through the selec
Sevantage of ateratosin eri of the ens stem
"Ampliar emerged rom tesa 200 millon ys oo, Oe ran, the era.
came ne domina nd anima ot athlon cups ved ut
mo anima spec Aral hero he odon sued he ser and came te
cesos manmat he ses mamma were nal nur sectores ed
ince, The remained sal and incompicuo unite extinción of he dins wich
‘ceed around 65 milion years ag. Te vacant ecological niches were qui ied by
moras Primate ao began e sal nua ee dling imeciors age at
Cto primates wth omar facing ee anlage bains, eventually ed
sn ass ve | e minh appear in Aes round 25 mio er ao, every rhing
neon en re | int four major species rangtan gras dimpanzes and humans Our aceso ac
EEE ge | gure pedal around 37 millon yes ago and dscoveredtooeking around 25 mi
wom Jon ys ago. he fs hominis o eave Alia, Homo erect do sound 12 millon

33. yrs ag and seattred aos Europe ad Asia, Homo neandethalisevoledin Western Eu
‘ope, eventual tobe repac by Homo sapiens, which evolved in Arica around 100.000
years and spread thoughout the worl. By 30.000 years ago Home sapiens had replaced

The evolution f age brains made posible the development of toolmaking re build
ing. and language. wich in tur permitted he development of complex soi tutus,
Large brain lo provided large memory capacity and the ble to recognize pattern
of events inthe past and to plan for the future, Because an upright posture isthe size
‘ofa woman’ bith canal and therefore the ze of the head that pass tough much of
the brains growth must take place afte Bt, which means that chen equi ane
tended perio of parental care Thi period of apprenticeship enable the developing brain
to be modified by experience

‘although human DNA fers fom that of chimpanzees by ony 1.2 percent, our brains
are mare than thee ties larger whieh means hat mal number of gene responsible
forthe crease inthe size of ur brains As we wl sein Chapter 3, these gene appear to
retarde events that stop brain development, esting ina phenomenon known ameter,

THOUGHT QUESTIONS.
at useful functions are provided bythe fac tht a human can be avr?

ow sti tat selecta for during the evolution of our species?

Are you suprised thatthe france inthe DIA of humans and himpanzees sony

12 percent? How do you fee! about this fact?

3. feu species continues to evolve what kind of changes do you think might occu?

Most of the research described in this book involves experi
menton on Using an

our on purposes, we shouldbe sure that what
tre are doing is both humane and worthwhile I believe that
good case can be made that research on the physiology of be
havior quals on both counts Humane treatment isa mater
of procedure, We know how to mainta laboratory animal in
good health in comfortable sanitary conditions We know how
toadministeranewthetics and analgesics so hat animals donot

sulle during or after surgery, and we kno how to prevent in
Feetions with proper surgical procedures and the use of ai
‘otis, Most in

rally developed societies have very ui
regulations about the care of animals and require approval of
the experimental procedures used on them. Theres

for misreaing

nal in our care In fat the vast maj
Iowa human

laboratory anim

We use animals for many purposes We eat their meat and
gg and we dink their milk we turn dei des into leather
treat People's diseases we tran them to do ef work on

loan: wenos hey decid that hey wl Hein
our homes. The fact i, we have been using other animals
Aroughout he history of our species +

0 ces much more Salen among an
esearch docs. As Miller (1989) notes pet 0
ers are mot required to recche permision from a

‘hoard of trae thatthe ar pr fr

34. BETA cir 181: 003030 Porcine Proy ‘ov ablongmancom/caronée

‘experts ihatinludes a eterinarian o house their pets nor are they subject per
‘dic inspections to be sre that their homes are clean and sanitary, that their pets
lane enough space to exercise propery or that ther pci deteare appropriate Sch
fic researchers ate Miler als notes hat iy times more dogsand ess ae led
mane cities each year because they have been abandoned by former pet
than are used in scientific research,
a person believes that it wrong to use a
‘of the benefit vo humans, there i noth
[OF the vale of scientific research with an
{om the very beginning. Moral abolutes cannot be sete logical ik religions
eli they can be accepted oF rejected, ut they cannot be proved or disproved,
My arguments in support of scene research with animals ae based on an cra
Aton of the benefits the research has to humans (We should abo remember tha re
Search with animals often helps eter animals procedures used by veterinarians, as.
las those sed by physicians, come from such research)

Belore describing the advantages of research with animal, let me point out tha
the use of animals in research and teaching a special target of animal rights ac
tists. Nicoll and Russell (1900) examined twenty-one books written by such ac
tits and counted the number of pages devoted to concern for diferent uses of
animal Next, they compared the relative concern the authors showed fr these uses
to he numbers of animal acwall involved in each ofthese categories. The results
Indicate hat the authors showed relatively Ke concern for animal used for food,

ining or furs or for hose Killed in pounds In contrast, although only 0. percent
fof the animal are used for research and education, 68:3 percent ofthe pages were
‘devoted to ering this use. In terms of pages per million animals sed ih
thors devoted 0.081 fod, 0.28 to hun

other anima in any way regardless
“anyone can sa o comince him or her

ah For this person the ise is closed

for escarch an education than fr food and 29 times more han for hunting, Even
the ase of animal fo fre (which consumes vers as many animals as research
education) attracted 419 dines les attention per animal
The disproportionate amour val rights activins show to-
ward the use of animals in research and ed
Uhisistheone indpensehleuse of animals. We can survive without eating animals. we
(an ive without hunting, we can do without furs. But without using animals for re
Search and fr training future researchers, we canna make progress in understand
¿ng and treating diseases In not too many years our scientists wll probably have
deselopeda vaccine that will prevent + spread of AIDS, Some animal sights
sci believe hat preventing the deaths of laboratory animal in he pursuit of
ich a vaccine isa more worth goal than preventing the deaths of milions of hu
will occur as rent of the disco ia vaccine sn found. Even diseases
already conquered would take new victims if drug companies could no.
ger use animals If they were deprived of animals, these companies could no
Tonger extract hormone used to treat human diseases and they could not prepare
ny ofthe vaccines that we now use o prevent them
“Our species is beset by medical, mental, and behavioral problems, many of
‘whieh can be sole onl throug biological research, Lt us consider same ofthe
major neurological disorders Strokes, camed by bleeding or occlusion of blood
‘ese within the brain, often leave people party paralyzed unable o read, write oF
“converse wth their friend and fami. Bai research on dhe means by which nerve
‘ellscommnicate with each other has edt important discoveries about the causes
‘ofthe death of brain cells Th research was wot directed toward a specif practical
{goal the potential benefits actual came a surprise tothe investigators.
"Experiments based on these results have shown that a Blood ese e
the bran is blocked for afew minutes, the part of the brain that nourished! by that
{esse wilde, However, the rain damage can be prevented by fst administering a

35. y lado medical weatme
“damage caused by strokes. But involves opera

pinching of à blood sewel. (The animal are anesthetized, of
course) Some of the animal wil sustain brain damage anal vil be ile that
their brains can be examined. However, you wil probably agree that rescareh tke
‘his jt a egtimate as using animals for food,

AS you wil earn Tater this book, research wit
duced important discoveries about the posible causes or potential treatments of
neurological and mental disorders, including Parkinson disse, schzophn
‘manicdepresive ines anxiety orders, obsesvecompulsve disorders, anorexia
nervosı, obexiy, and drug additions. Although much progres has been made
hese problem ae ill with us, and they cause much human sul

I has pro

continue our research with Laboratory animals, the problems will m
Some people have suggested tha instead of using laboratory animals in our Fe
search, we could uso tse cultures or computers. Unfortunately, nether sue cul

tures nor computers are substitutes for Ihing organisms We have no way to such
choral problems such as addictions in tae cultures, nor can we program a
Computer to simulate the workings of an animals nervous ten, (we oul
‘would mcan that we already had al the answers)

This book wll cise some ofthe many important discover
10 reduce human slfering. For example the discovery of a vaccine for polo, se
Fious disease ofthe nervous tem, involved the wc of hes moneys. A you A
learn in Chapter 4, Parkinson's disease, an incurable, progresine neurological dis
‘order, has been treated for years wih a deg called 1-DOPA,acencred through an
mal research, Now, because of rescarch with rats, mice, rabbits and monkeys
stimulated by the accidental poisoning of several young people with a contaminated
batch of snthetc heroin, patients are being te à drug that may actually
slow don the rate of brain degeneration. Rescarehers have hopes hat a drug ill,
De found to prevent the brain degeneration altogether

The easiest way o just search with animas sto point o acta and potenti
Denes wo human health a ae jus done. However we can aso jsi
search with a ls practical but perhaps equals importan, argument, One ofthe
{ings that characterize our species ia que for an understanding of our word, For
sample, astronomers study the universe and y to uncoveritmysterie Even their
Aiscoveries never lad o practical bene such as beter drugs or faster methods of
ansportation the fat that they eich our understanding ofthe beginning and the
fate of our universe jus thei efforts. The puri of Rawle sl a wort
hile endeavor Sure; the attempt to understand the universe within uso ner
Vous system, which i responsible forall that we ate or can be als valuable

Wha is physiological psycho; and what do physiological pachologiss o? By the
time ou finish this book, you wil have as complete am answer a can give to these
“questions but perhapsit wo he the eld snd arcs that
are open o hose who specalize ini before we begin our su in earnest
Physiological peyhologiss study all behavioral phenomena that can be ob-
served in non imals They attempt o understand the physiology of beba
ior the role ofthe nervous system, interacting withthe es ofthe body especially
theendocrinesstem, which secretes hormones) controlling behavior. They study
such tops a sensory processes deep, emotional behavior, ngesine behavior, a
rene behavior, sexual be behavior, an i and memory

Cores Nevescence ARE

ilogico à
na ses
bho rr pe
tera prone a

36. {CHAPTER 1: Oran of Peal Polos ov alongmancomiationse

They also sud animal models of disorders that affict humans, such as anew,
depression, obsesions and compulsions, phobias, prychosomatie illness, and
schzophrenia,

‘Akhough physiological psychology i the original name for this Held, several
her terms are now in general wc, such as Dai pychlog, opschalg, fs
dobla bat newnacince. Most profesional physiological psehologsts
Ihave vecched a PhD. from a graduate program in psychology or from an inter
iplinary program. (My own university awards a PLD. in Neuroscience and Beh
jor. The program Ihe departments of pychology
ogy, Biochemistry exercise science, ad computer science)

ssological pochology belongs to the
tis concern sheneves with all aspects ofthe nervous system
ints: physiology, development, and functioning. The research of
ranges rom the study of molecular genetics to the study of social behavior. The fi
hhasgrown enormously inthe lst few years: meetings ofthe Society or Neuroscience
are attended by well over twenty thousand members and graduate students.

‘Mout profesional physiological pochologi are employed by colleges and uni
es here they ate engaged in teaching and research. Othersare employed by

dom devoted to rexeareh-—for example, laboratories owned and operated by
Mal governments or by private phitanthvopie organizations. few work ii
‘sty, sally for pharmaceutical companies that are interested in asesing thee:
{ects o drugs on behavior, To become a professor or independent researcher, one
mus eceie doctorate—ustallya PRD. although some people turn to researeh
Alter receiving an M.D, Nowadays, mos phological pschologiss spend two years

temporary posidoctoral poston, working nthe laboratory of a senior scientist
to gain more research experience. During this time, they write aries describing,
ther resareh fh

ications are an impor
Tio ber fields often overlap with that of phsilogieal pschology: nunlog
and experimental neuipyeolgy. Newtons ae physicians involved in the diagno

id ereatment of diseases of the nervous stem. Mos neurologists are solely in-
‘obed i the practice of medicine, but a few engage in research devoted 10
advancing our understanding ofthe phisiolog of behavior. They stay the behar
jor of people whose brains have been damaged by natural cases, sing ad
thain-scanning devices to study the activity of various regions ofthe brain asst
ject participates in various behaviors. This recarch I also caricd out by experi
‘mental neuropychologiss—acientiss with à Ph.D. in psvehology and specialized
Training dhe principes and procedures of neurology

‘Notall people who are engaged in neuroscience rewarch.
Many research technicians perform essential —and intllecwall rewarding-ser-
‘ces forthe sins with whom they work, Some ofthese technicians gain enough
Experience and education on the job to enable them 10 collaborate with thei em
pers on their research projet father than simply work for them,

ge ld of murcia, Neuronien
“anatomy, chem.

INTERIM SUMMARY

Ethical Issues in Research with Animals
Reseach on the physiology of behavior necesariy involves the se of laboratory animals. 1
‘incumbent on al zenit sing these animals ose that they are housed comfortably
and treated humanely, an awa have Been enacted to ensure that they are Such research
as already produced many benefit to humankind and promises to continue o oso.
Physologkal psychology (alo called biological psychology, boprehology pychobi
‘oy. and behavioral neurocence) ald devoted o our understanding of the pryilogy

37. of behavior. Physiological psychologists are lied with other sentis inthe Broader fla
‘of neuroscience, To pursue a career in physiological psychology (or in the ster fi of ex
erimenal neuropsychologp), one mus ota à graduate degree and (usual) serve tuo.
Years or more ab "porte" à sent pursing further taining

THOUGHT QUESTION

Wy do you think some people re apparently more prat about ung animals frre
Search and teaching than abou using them for other purposes?

The brain ia complicated organ. After all, iti responsible for al ou ailes and
¿our complex. Scientists have been studing his organ or a good many years
and (especial

ple sentences: therefore, his book.
Contains alot of information. T have tried o organize this information logically
telling you what pou need to know in the order you ned to know it (Ale lt un.
derstand some things. you need to understand other things fir.) have ao rica
to write as clearly as posible, making my examples as simple and as id as can
Slow cannot expect to master the information in this book by simply giving a
passive read you will hive to do some work,

nig about the physiology of behavior involves much more than memori
ing facts Ofcourse, there ae facts o be memorized names of parts of the nervous
system, names of chemicals and drugs, scientific terms for particular phenomena
and procedures sed o investigate them, and so on. But the ques for formation,
isnowhere near completed: we know only anal fraction of what we have to learn
And almost certainly many of the fate that we nom accept will someday be shown
do be incorrect, Mall you do is earn facts, where will you be when these facts are

note to obsolescence is knowledge of the process by which facts are ob-
ence, ct ar the conclusions scheiss make about thir observations.
you learn only the conclsions obolescence is almost guaranteed, Yo wll have
10 remember which conclusions are overturned and what the new conclusions ae,
and that kind of rote Tearing is hard o do. But if you ea
Strategies the sient use the obsersations they make, and
tothe conclusions yo will develop an understanding hat seas revised when nen
‘observations (and new Tats?) emerge. I yo understand what Hes behind the con
‘usions then you cn incorporate new information into what yon already know ad
sic these conclusions yourself

I recognition of these realities about learning, knowledge, and the scientific
method, his book presents not jus collection af fats, bt also description of the
procedures, experiments and logical reasoning that sient have used in their at
emp to understand the physiology of havior: in the interest of expediency, you
focus om the conclusions and ignore the process that leads o them, you run the sk
of acquiring information that wil quickly become obsolete. On he other hand i
you ry o understand the experiment and see how the conclusions Follow
ests, you wll acquire knomleige that Hives and grow

‘Now let me offer some practical dice about wudying You have been tud
throughout your academic career, and you fave undoubtedly Icarned some wchul
strategies along the way. Even if you have developed efficient and effective study
‘hills at least consider the poly that he some way to improne them,

Ti posible the fis reading ofthe assignment should he as uninterrupted om

the it: that i read the chapter without worrying much abona sememberin

38. BETEN, carter 1: 0107401 Physiologica! Pycholoay

etal, Next ater the Bs class m
‘again in earnest Use a pen or pencil you es Don't usa hihihi
Sweeping the let tip of s highlighter actos some words on a page provides some
‘Sant gatification: yo an even imagine hat he highlighted words wow be
trusferred o your knowledge base, Vin have selected what important and
sen you review the reading anigument sou have only to read the highlighted.
‘words But this san si
Bective, not pase. Force yourself to write down whole words and phrases The
act of puig the information | wore il ot on ive ou so
to ty shortly before the next exam but also pa something ino yr head (a
À helpful a oxam ine). Using highlighter pts of the lating uni a late dat
repaso the information in your own words starts the learning proces igh then
A oo way o get yourself to pt she information into your own words (an
into your own bran) is 10 answer the questions in the study guide I yon ca
or answer a question, look up the answer inthe book, dow the Bok, and wi
answer don The phrase lw the dk important. you copy the ane, yo wil
ict very litle out ofthe exercise, However ou make youre
formation lng en
later, The import

the qui. The behaviors that ead to Tong
{erm earning te doing enough thinking about he material to summarize itn your
un word, then going though th
Before you begin reading the next chapter, let me ay a few things about the de
sign of the bok that night help yon with your suis. The text ad stations are
raed as closely as posible. In my experience, one of the mot amnoxing aspects
‘of reading some books not knowing when to look at an ilusion. Therefore, in
this book you wil find figure references in boldlaced italics (hike this Figure 5.6.
ich means op reading and look at the Figure.” These references appear in lo
‘Caton think wile optimal yon Took away rom dhe text then, you will be as
‘Sve that you wil ot be interrupting line of reasoning in a crucial place and wi
thot have to reread several sentences to get going again. You wil find sections Hi
thie Figure 1.1 shows an ligas This alligator certainly al out
in alinear fashion: we can dran a salga ine that starts between its eyes and com
tines dom ‘oft spinal cord. (See Figure 4.1)" This particular example
sou Took atthe figure
other cases the material more complex and you wl have less rouble you
wo watt lok or before you stop reading and examine the istration,
ou wil noce that some words nthe text are Hal and other are printed
in boldface, Klis mcan one of two things her the word is being esd or
plais and not a new term, or! ng out anew tern that Hot necessary
{or you to lear. On the other hand, a word in ola sa new term that you should
yt learn, Most of the boldfaced terms in the ex ae part ofthe vocabulary ofthe
‘hysiological poelologist. Olten, the will be sed again ina later chapter Avan aid
to your ing, definitions ofthese terms ae printed in the margin of the page,
“long with pronunciation guides for those terms whose pronunciation is not ob
“us. I addition, «comprehensive index atthe end ofthe book provides à ist of
terms and topics, wth page references
tthe end ofeach major section (there are
ther yo wil find an Interim Summary whieh prendes place for You o stop a
ink again about what yo have jus red wo make sure that you understand the
rection in which the dixcusion has gone. Many imerim summaries ae followed by
Some thought questions, which may serve to stimulate your thoughtsabout what yon
ave leaned and apply them to questions that have not yet been anoscred Taken
together, these sections provide a detailed summary ofthe information introduced
the chapter My students tll me that they review the interim summaries jus e

¡hos words dwn

pally three to ve of them

39. Okay, the preimin
sink your (metaphorca) teeth
‘mon important element of the

cover The next chap
10: the u

ture and une

Models of Brain Functions

ene Descartes ad o way tot the
‘operation of he neous ster He
‘however understand how the sa
‘erin the Royal Garden a Sai
‘Germain were powered and contrae,
ae ei to view te Body a
complicated pic of plumbing Many
‘arts ue followed Decorar en
“mole ung tecnologia eves at
‘were (hinab tthe me o plain

at motvate people o use ari
al devices to explain the workings o
‘he bral The ment portant sr. |
‘suppose that he rans enormausy
complicated. Even the most comple hu
man mets re many tines simpler
then the ran ad Dee they have
been designed and mad y people,
People an understand them In ri
{aleve an d seme othe ngs
{hat he bran does then perhps bath
the brain and the device compl
{he tak the sae a.

Mont model of rain union deve
open teas ato! ne sent
entry have been based on the mod.
‘rn, genera purpose digital computer
‘Acai, they have been Bed nat on
{he computers thomas but on com.
puter programs Computers canbe po
‘rammed to store any kindof informs
‘otha an be coded in nutes or
‘wor an se ay logia problem,
atan be expt described, and can
compare any mathematical equations
atan e rite.Terfoe in pic
‘lat east hey o be programmes.
o e things we do parco, rm
‘ber make deduction sche probe.

‘he contruction computer ro.
grams hat multe human rain une
ons an pt dry te nature of
‘hese functions Forirstance toco
Suc» program and simulta per
pion and esco of cera
‘ype of pates he investigator

fore to spy precy hate
‘ued bythe sk of parte percp-
ton fe program fl to recoge
{he pater then the meister
‘rows that somethings wrong wth the
‘modelo with the way thas been
Pementedin te program. The met.
‘utr reves the model vies ag ond
eps working unt i finaly wots (or
treo she gives up the ask as be
ing too ambos,

ea, satel th inventor
‘the ins of processes the ran must
perform However nee al mare
{han one way to acomplia aparto
‘goat ets of computer modeling have
Pointe ut tat ts poe rie à
rota tat performs. task hat the
human ain peters and come uo
it exact the same rests but does
the takin an entre erent ay. in
ac. some sy gen the way at cam.
putes werk and what we know abo
he sure ofthe human dan, the
computer program garant
‘won ferent,

“when we Bose amade of bain
funcions on a pica device with
ich we ae fria, me roy e a
Vantage of being abe thik co
‘ete about something that iit
Lo observe. However the bain does
not wor ikea computer then cur
mod wil no lu ey much bout
{he bain su mode re contained
(reste) bythe computer
metaphor they wl be able odo Wings
‘nl the way hat computers and
‘he the an an actualy do some
“ferent sors of tings hat computers
not do, the models wil never con
tain thee features

In ac, computers and brains are fon
Samen erre Modern computes

aril eves they werk one step at
‘ime Sv om te Latin rer o
Jon refers to events hat occur nor

something you can
ns of neurons the

de ane afte the ther) Programs con
‘of ase of trons ordi in
Computers emery The compute 19.
lows these sions, one ata tine
Because ech of tes tps aks uma
complicated program wil ake more
time to erect But we do som tings
‘erly ult that computers tato
‘ery lo time 10.0. Te ber exampe
Visa perception We an recoge a
Complex ire bon tach in
Prone: or example, takes about he
{ame amount of tre to recogni
nds oe a oes tert am.
ple ange. The same ot re ata
fora eral computer A computer must
amine the scene tough an input
esc someting ea sevi cam
(2 Information abou the big of
‘ach pin the tue mut eco.
ardt number and red na
mama cation Then the program
“ines each meron location one ta
me and does cautions that deter
‘mie ie actions of ies gen er.
{re and shapes finaly es tae
termine what hese shapes represent
ecogiing à ace takes much longer
‘than recognizing a ange nat even
the best computer programs do ter
teen recognizing faces.

"nte srl omer, the brain's
‘paral procesos nui many at
ferent mods (lectins of crt of
ar work smataneocay at er
tasks À complex tsk broken
‘down into mary smaller one an ps.
rat module work on each ofthem Be.
au ne rain cons of many ions
ot neurons can fort devote it
ferent cures of nerons to cient
ta M so many tings happening a
‘he same ue, the nk get done
au.

Very recent rer have
turned the tables red hare gon
ering made of computer at

40. BET care 1: on tio Peony

‘resemble he nevus stem. The ee
‘mers ofthese compares are based on
‘ewe cl, and the er (at govern

Le ay they tera are Boe onthe
‘ules you wl aon ab in Copter 2
Furthermore, intend programming

‘these model to perform function re
res ge em information tht
rs thom tenn Js ti
Br does Someday we may even see
‘xpi computers, sng materia sim
Tart the found in the body scents

‘wor alongman convearsente

re developing pohmers peca organic
pounds tan takeover the luc
Fons fe sion cps sein the
tegrated cats hat make o presen
Some.

UNDERSTANDING HUMAN CONSCIOUSNESS: A

PHYSIOLOGICAL APPROACH

Physiological pychologis believe that the

funcion performed bythe brain.

Study of human brain funcions bas hel

some insight int the nature of human conscious

ess, which appears to be related o the language
sions of the brain. This chapter described one ex-

ample, the effects ofthe plibrain operation

à us gain

THE NATURE OF PHYSIOLOGICAL PSYCHOLOGY
3. Scientists attempt to explain natural phenomena by
means of generalization and reduction, Because
Dhoiologcal porchologis sf pa
chology and physiology they employ both types of
‘explanations
4, Descartes developed the first model to explain how
thebrain controls movement, based on the’
states in the royal gardens. Subse
tors tested thei ds with sch

NATURAL SELECTION AND EVOLUTION

Darwin's theory of evolution, with is emphasis o
inctio, helps physiological psehologss discover

the relations between brain mechanisms, el
and an organizo adaptation 0 environ
6. We owe our status asthe dominant species to ou
bipedal stance, our agile hands, our excellent vision,
and he behavioral and cognitive abies provided by

oa wide variety of environments exploit a wide ar
fy of resources, and, with the development of la
unge, ori large, complex com

ETHICAL ISSUES IN RESEARCH WITH ANIMALS
sin

‘what we know about the

‘ding that ofthe nervous system. Thisknowledge is

essential in developing was to prevent and reat neu-

‘ological and mental disorders.

7. Scienüfi research

CAREERS IN NEUROSCIENCE
8. Physiological pyetologss study the physiology of be

ng research with animal, They se
search methods and findings of other neuro-
ins in pursuit of ther particular interests,

Alan, JM. ling Bain New Yorks Scenic American
Buterhed, 1. Phe Ong Mud Seo: 130-1800, Nee

Daren, AR, Dale mr Eme, Reo, and th Hamon
in Nee rk nam 104

Finger. Origins Nei: À Hier of Explain ine
in Penn New York Oxford nine re, 100
Setar Dead Schul, 8.6 À iyo Med Pillo

Bain and Beter Course
rn edles sem
ve Bra and hi contains a ris of 2 olin ee
tures deslopedat Now York Une ng mo keine
‘spl pines ve st cer netics she

roc Case Paper onthe Paint Tan
you caldepupsjelassvBrocalpert- hm

861, err Pl Beca publ e report eatin
the low of ngage to damage o the et ameno he
Sphere of the ban Tse presentation ol Doc
pen.

41. ‘The acento Man by Charles Darwin

yo lbepvsjehlsiDarwinescentine tm
This pondes cs to seven fhe chapter pba y
{Cares Darin in Di book The Dn Mer (187)
‘hic he not ii om the evn of mn.

end A DIAN) mendelcamgarden him
Ths se ink tna 1 demotradon af he prin

sone es EE

pl rin Syndrome
ceda hin
An online demon

Spira Conscousnest
ce IV IES Ban’
Spt Brain Consceunen him

Ab operon and he blo of ql pen

42. Structure and
Functions of

Cals ofthe Nervous

Cells of the =.
Nervous System 2

Communication Within
Neuron

1. Name and describe the part fa neuron and explain tei functions.

2. Describe the supporting el ofthe central an peripheral nervous systems and
ere and explain the importance of the blood-brain barr

3. Briefly describe the neural circuitry responsible for a withdrawal reflex and is
Inhibition by neurons in the brain.

4. Describe the measurement ofthe action potential and explain how the balance
between the forces of diffusion and electrstai presu responsible forthe
membrane potential.

5. Describe the role of fon channel in action potential and explain the al-or-none
Taw and the rate av

6. Describe the structure of synapses, the release of neurotransmitter, and the
activation of postsynaptic receptors

7. Describe postsynaptic potential: the tonic movements that cause them, the
processes that terminate them, and their integration,

8. Desribe the role of autoreceptors and axoaxonic synapses in synaptic
‘Communication and describe the role of neuromodulators and hormones in
nonsynapti communication

43. OGUE

Unresponsive Muscles

Katyn D was getting desperate Al__parment quit ew weeks ago, andve west With à den fling of right
er ife she hd ben heathy and active, ak over hiso temporary ink a relied that heat of beating
ting wey and Keeping fit with sors have chance of geting the job perma: seemed take 2 tof efor She man-

ana regular exec she wentto er net but elsif bosses are agedto nah the tense, bu ne
heath cub almost every oy frases. watching meto see wheter tm geod ate after she packed up her
Son of owimpact aerobic followed by enough forthe job Katyn andhar cue diet or ome saying hat
{swim But several months ao, she be: _ phyicanagredhatiereasedsess she had bad headache.

an hai trouble keeping upwihher out bete caso o er problem. 1

‘she elephoned her pcia, who

ual schedule Auf, She oundher” prefer not to ge You amy medion at immediately arranged fr her 1 901
se eting ted toward the end other nstme, es "but you dont fl th hota tobe seen by Os Y, ane

erotics Her rms partir, betterssenwellhuescateriocket _ rologet Dr teed tos escrito
Seemed to get avy Men hen een you" ‘ther symptoms and examine er
tered the pool and arta swimming, She dde beer for we but ay Sho so Kathy “Ti
she ound hat mas hard fe ten Of uen her symptoms Got know what may be ang Jour mp.
ms ve er head she abandoned the wore She quí gong tothe escu toms 18 coto give you ection
Cond the bah andthe an found that se even Rad ty. and watch your ructen She gre
Sidestote and entre inte, She fig à das work she ns cerain Some odes tothe nr, wha et he
‘i othave any Nile symptoms 50. at people ware noting hatshewas oom and came back wth syringe, D
Seto hesl hase needed mre no longer er ey sal andshe was. tokit nabbed Kathryn and
Sleep and parapsshe hou eut ate Sri at bar chances forthe promo- ced the dra, She surted queno
mon. tion weesippingamay.Oneaftmoon ing Katyn about har jo. Kaya

‘Over the not few weeks however, sheweteleekupethedbckentne tr Par oe almost swe
‘hing on got worse. Arab cases wallandreledmatshecauliherdy pr Asthe quemen confined the
‘were becoming an ordeal Me nsrucor sehr eels were roping. end er ee that I ar geting ear and

came concerned and suggested that Model si weighed a hundred ear oak Se strings he ck
Katto se er doctor she dd 0, ut pounds st then one of her super: andtooka dep rest Yes she wat
he cou find nothing wrong with er. sos ame over ee desk sat down, ur Mer eng ma tuning! She
‘She was not anemic showed no sig ot andasted her tofilimin on the pro- stood up andre ar sm above er
aninfeton and ered tobe well” resis had been aking on anew” Med “Look” he sd ha excerent
‘outed He asked how tings were projec Ash takes, she ound esl growin, ca do thi again Fv go
Going ar work ‘tng weaker and weaker Herjw mg Back What wot hat ou
“Wil tly ve ben under some as geting ed even er tongue was give me? Am cred?

presu she id “The head of my de- geting ned and he vie war getting

happening ce to abo con

Dane ace pan eae peroo acia, teem reer

Sachs aes mad pone ye ions enn he
Tischer dessert

lls that are

cand functions of the mos important cells of

the nervous system. Ino the form of ight, sound waves, odos, ase, or

contact with objets he environment by specialized cell called seme

sory neurons. Movement are accomplished by the contraction of muscle, which are
rolled by motor neurons ( ins original sense tore.

ferto movement, not a mechanical engine) And

‘motor neurons come the interneurons neurons th

betwen sensory neurons ad
Be entirely within the central

ap nen Ar
amor bout hee ge

‘ry nthe cen nor

44. MIE tar 2: suceso funcions! Ces fe Nono tem. won ablongman.comiationse

Es] rons and Supporting
Ce tr an mece
tdi ne folowing secon.

central neous sytem (25)
pepa eros ten
core
a ning es a
soma Theta aon,
ende Atar ie
spp pon ne
sen Teg mn. gi

nervous system. Lvalinterneunns form circuit with nearby neurons and analyze
‘tal pieces of information dy interneuron connect cect of lea
«regio ofthe brain with those in ter regions. Through these connections
reais of neurons throughout the bra sions essemial o aks uch
ring remembering deciding and controlling complex behaviors
ons are there in he human nervous system? 1 have wen exits
‘of beeen 100 billion and 100 billion, but no one has counted them et
To understand how the nervous stem controls behavior, we must Fist under
its parts th ells that compose i Because this chapter deals with cell ou
need not be familiar with dhe structure of the nervous system, which is presented in
‘Chapter 3. However you need to know that the nervous stem consi of o basic
“vision the central nervous stem ad the peripheral nervous stem, The entra
‘nervous system (CNS) const fe pars that are encased by the bones ofthe skull,
And spinal column: the bran andthe spinal cord. The peripheral nervous system.
(NS) is found outside these hones and consi of the nerves and mon of the sen
sory organs

“The first par ofthis chapters devoted toa description of th

ofthe nervous system-—neurons and ther supporting clls—and tothe blood-brain

Barre, which provides neurons inthe central nervous system wih chemical ol
In rom the rest ofthe boy

Neurons

Basie Structure
The neuron (nerve cell) i the information processing and information trans

s ste. Neurons come in many shapes and varieties,
according o zed jobs sey perform. Most neurons have in one form oF
Another, the following four structures or regions: (1) cell body or soma (2) den
‘ites; (8) avon; and (1) terminal buttons, (See Animation 21, Neon and Support
ing Ct)

Soma. ‘The soma (cl bod) contains the nucleus and much ofthe machinery
that provides for the life process of the el, (See Figure 21.) ls shape varie con
idea in different kind of neuron

Dendrites. Dendonisihe Greek word for tee and the dendrites ofthe neuron
Look very much lke tees. (See Figure 2.1) Neurons converse” with one another,
and dendrites serve as important recipients of these messages. T

pas rom neuron to neuron ae transmitted actos the synapse, junction Bete
"terminal buttons (described ater) of the sending cell and a portion ofthe so-
‘matic or dendrite membrane ofthe receiving cll. (The word sap derives from
‘he Greek sunaptin, to join together) Communication a a smapae proceeds in
‘one direction rom the terminal button o the membrane of the other cell (Like
‘many general rules, his ome his some exceptions. A else in Chapter d,some
map pas information in both directions)

‘Axon. The axon it long. slender tube, often conered by a myelin death (The
inyein sheath is described later.) The axon carries information from he cll body
to he terminal butons. (Se Figure 2.1) The baie message it carries called an ae
tion tential This function san important one and wil be described in more detail

45. ots of he senos Stem METRE

‘The pica paris 01a mate neuen.

chapter. For nos it slices o say that an ac
riel clectrical/chemical event th

axon next tothe cell ody a rav-
ns. The action potential à

Tike a brel pals:
always ofthe same sire When i reaches à
point where the axon branches, it splits but doca not di
mini in ie, Each branch receives fulltrengh action
potential.

Like dendrites axons anther branches come in di
ferent shapes In ac, the thee principal types neta
are last according tothe way in which their xen

cs leave the soma. The
Figure 21 isthe mon common wpe
heron the soma
tothe wunks of ce

Bipolar neurons gie rise o one axon and one de
etree, at oppositeendsof the soma. (See Figure 220)
Bipolar neurons are aly sensory

tes detect event occurting in the en

tral nervous ste
“The tied wpe of nerve cll isthe unipolar neuron.

thas only one sal, which leaves he soma and vies into

two branches a short distance sway (Sec Figure 226)

Unipoter bipolar ne

informatio the CNS. The eee

Tike branches outside ate dendrites that detec
sory information. The branches of the ae

‘within the CNS end in terminal buttons The dendrite of

‘ont unipolar neuronsdetect touch, temperature changes

en ee
these amor

47
{=

AS

sro. 2 A igor nern, primary ona inser rem
{forename sen and won) Auniplr nern, sua
Inte somatonemory sem Rae pa angel)

Care ene Dents ae sono
Tee

canos
Daran

Sara

pes
non

w

46. al rapped in
Terres look somehing.
dre. (Soe Figure
able, nerve bers
and.

47. coset etico Sten A

‘An rene of he ati connections between newons. The roma represent he recta of
‘tow of atomaton

Internal Structure

nal structure of atypical multipolar
he boundary ofthe cel. It consist of.

cell Other proteins control access o the interior ofthe
barring others, Sl ot

as transports atve carrying certain molecule into or out ofthe cel, Because

the proteins hat are found in the membrane ofthe neuron are especially import

inthe transmission of information, shee characterises will be dicted in more de

tail Ear inthis chapter.

‘Tne cel filed with eytoplasm, ji substance tha co
ined structures, jus as the body contains specialized organs. Among these sr
are mitochondria, which break dow nutrients such a glucose and prone the cl
‘wth energy to perform is functions Mitochondria produce a chemical called adeno-
‘sine triphosphate (ATP), which can be cd thronigho the ellas an energy source.
Many cons ago mitochondria wee techn organisme that came to “infect langer

sa

host, ey became fl totem ad ¿me à permanent parto!
Mitochondria sill contain ther own genetic information and muliph independent
‘ofthe eelsin which they ie. We inherit our mitochondria from our mothers fathers
sperms do not contribute any mitochon

rucleus (rom the
contains the chromosomes, Chromosomes, as ou hive probably already earned,
const of lng stands of deoxyibonueleie aid (DNA). The hromosomes have an
important function: They contain the recipes for making proteins, Portions ofthe
chromosomes, called genes, contain the recipes for individual proteins.

modos kn iste a
adenosine viposphae ATP
den on) Arcs ot
nia cres
cremoso À sans OWS,
ence cones rete
omo
ronyibonue ca (OWA)
(are y bone day À
loa conse conc
‘Nepean, nar NA

air Neonat be

48. DER raster 2: sucre na fuctis! Ces o! te Menos Sem ov ablorgman.consatonóe

teen Forest
Vicar, contes
ostras oia
copii nor A sc
a acces
Eset rons at
Fine agin re on
mtl y 0100)
Ring sans ner pe
‘eames rage amd
sow copa tec
“Stare von peo pace

mien
ee

‘re pra ner cures a maior neuen.

Po
exposed toa detergent,
Sole an. ling a matrix of insoluble strands of protein, This matrix, called the
‘otoskeleton, gives the ncuron is shape, The cytoskeleton is made of various kin
{of protein strand, linked o each other and fo
Besides providing structure, proteins serve as envyines. Enzymes are the cells
mariage brokers or divorce juges They case particular molecules to join together
fat gets made from thera materials com
ne which molecules remain int
Proteins are also invohed in transporting substances within the el, Axons can
be extremely ong, relative to ther diameter and the sic ofthe soma, For exam
the longest axon ina human reiches from the foot oa region located in he base
fof he brain. Because terminal buttons eed some items that can be produced only
in the soma, there must be a sytem that can transport these items rapidly and ell
hi axopls (hats, the extoplan ofthe axon). This stem. aos
plasmic transport, san active proces that propels substances rom one end ofthe
other This transport saccomplihed by long protein stands called mi.
<rotubules, bandes of thirteen
tubules serve as air u
transported. Movement 1 terial buttons called mega
{Noplasmic transport. (Aner means “toward the fron) Ragradeaxoplasm
{tanspore caries substances from the terminal buttons back tothe soma. (eto.
so “toward the back) Anterograde axoplasmietramportissemarkabl Est up
10.500 mon per day. Retrograde axoplasini transport about halla fast. Energy for
‘orl forms of transport supplied by ATP produced by the mitochondiría. (See An.
imation 2.1, Newons and Supporting Cells)

progress of the substan

49. Supporting Cells

‘Neurons constte only about half the volume ofthe CNS. The rest consists of a

tia
The mos important sup 1 central nervous system are the mt
nei, or “nerve gh.” Glia also called glial el) do indocd gue the CN
at they do much more tan that, Neurons lead ery shehered existe
‘ulfered physical and chemical rom the rest o the body by
is nv the
and some a the exchange messages with other neurons hey
late neurons from one another o that neural messages do not get serambled
and they even act as housekeepers, destroying and removing the creases of new
roms that are killed by disease or inj.
There are several types of glial cells, each of which plays a special role in the
Iypesate asses aged and mii. A
ely describes he shape ofthese el
Awrocyes (or asi) provide physical support 10
in the brain, They
functions, They help to
newrons by actively ta
Kepa within erica levels Finally astrocytes ae involved in providing nourishment
Some ofthe asrocque's processes (he arms of the sar) are wrapped around
blood vessels. Other processes are wrapped around part of neurons so the somatic
mes of neurons are largelysurrounded by astrocytes Recent
gene that atroces receive nutrients fom
the capillaries store then, and release
sen needed (Tsacopoulon and Magic
Gure et al, 1909). Beides having a roe in

Int nape,
that are released by the term
‘When neurons die, certain kinds of astrocytes ake up
the task of cleaning away the debris. These cells ae able
to travel around the CNS: they extend and retract their
process (didn, or “ale ce”) and glide about the
‘amoebae do, When these asttocytes contact piece of
{brs rom a dead neuron, they pus themselses against
i ial enguling and digest
Phagocytosis (plagen, “wo ea
Considerable amount of injured tse to be el
{xtrocytes will vide and produce enough new cel to do
the tak. Once the deal tie i broken down, a frame
work of astrocytes il be left iin ates and
specialized kind of astrocyte wll form scar tissue walling,
on

The principal function of oligodendrocytes ito pro-
ide support to avons and to proce the mein shea,

caso neos ten EEN

gage eros
soot A ce nano.
‘essen ones ole
Prog ag te)
Lente)
nd ome es à a
andy ot eri.
clgodenecee ogo den
orien Age ot geal
tee ml este

ryt shee my 0) A

Structure and ation a astros whose process sound
pilares and nero the cn

50. BETEN carrer 2 Sc anche o Celso te Nenu Site sr ablongmancom/earonse

‘hich insulates most axons from one another: (Some axons are not myelinated and
Tack his ahcah.) Metin, 8D percent pidan 20 percent protein, s produced bythe
sligudendeocyes nding the axon, Thistube docs ot or
ous cab; rate series of segments, each approximately À
1) portion of uncoated axon between the segments (À
imiromee abbreviated jm, is onemilionth of a meter or onethowandih of à
Hinter.) The bare portion of axon called anode of Ramvier alters discoverer The
meint axon, then resembles sting of elongated beads (Actuals; he ead ate
1 much elongated—thet length isapprosimately 0 times thee wid.)

Agen oligodendrocyte produces up wo fly segments of mein. During
‘elopmentof the CNS, oligodendrocytes form proces shaped something like canoc
paddles, Each ofthese paleshaped proces hen wraps cf many times around
segment ofan axon and, while doing, produce Livers of myelin, Each pad
becomes segment ofan axons men sheath, (See Figure 27 and 280.)

As cir name indicates, mierogia arc the smallest ofthe gil cells Like some
topes asrocies they ctas phagocytes engulfing and breaking down dead ad
ing neuro But ln addon, they serve a one of te representatives ote mur
system in the ba rong. They ate pr

ail responsible forthe inflammatory reaction in response o brain damage:

Schwann Cells
In the central nervous stem the o
the peripheral nervous stem the Schwann cells peor
ons. Met avons in the PNS are myelinated, The mye
Ant os inthe CNS; cach segment co
mes around the axon, In the CNS the oligodendrocytes grow a
shaped! processes chat wa

An oigodendrce. uch fos te myelin hat surounds mary Formation myelin. uring deapment a roces an

ce
er arc ent re

nanas stem tah cel forms one segment olgodentro oan ent Sama cl thy ups elf

‘herein seat a) gosendrcte (Soma cl

Moins anne

e

Arges Min nea

®

51. provides myelin for only one axon, and the
‘ell—not merely a part of surrounds the axon, (See Figure

es te rico St ECM

‘he lod ain trie The ct that form the wal of

28} he capillaries in the body outside the brain have gaps that
Saal meet termine walsh apar
The Blood-Brain Barrier Beben ae ja

Over one hu à Eich discovered that if

dred years ago, Pa

‘Mie dye tsinjetel into am animal oodsiream al ses ex ‘eet uma eto
‘cept the bran and spinal cord wil be tinted blue —

the same dye is injected into the Mile ven
brain, the blu color wil spread throughout the CNS (Brad:
buy 1979, This experiment de

ctm the Blond and the Mid
brain blood-brain barrier

‘Some subntances can cress the blood-brain harrier others
‘cannot. Ths. is ti poral (jr Une mre, to
pass). tn mont ofthe bods the ells that line the capillaries do.
oi ogether abnalely tight. Small gape are found between
them that permit the free exchange of most substances be
tween the blood plasma and the ud outside the capillaries O
that surrounds the cll ofthe body. I the central nervous 3.
tem the capillaries lack these gaps therefore, many substances
‘cannot lane the blood. Ths, the walls of the capilaris in the brain con
Diood-brin brie (Sec Figure 2.9) Other substances mus be actively transported
"hough the capillary walls by special proteins, For example, glucose transporters
bring the bra ts fl, and other transporters id the brain of toxic waste products
(Rubin and Stan, 1090),

‘Whats the function of the blood-brain barrer? As we wl ce, transmision of
messages fom place to place inthe brain depend on a delicat balance betwcen
‘tances within neurons and in the extrcelaar fa that surround them the
‘Composition of the extacelluar id is changed even sight the transmision of
these messes wil be disrupted, which means that bran functions il be disrupted
The presence ofthe blood-brain barrier makes teaser to regulate the composition
‘ofthis Mai lali, many ofthe foods that we eat contain chemicas hat would
interfere with the transmision of information between neurons, The blood-bra
barrer prevents these chemicals from reaching the brain.

The bloel-bran brie isnot uniform ye nervous system, Ins

ris relatively permeable allowing substances that are exchided
here to eros freely. For example, the area postrema i part of he brain that
contes vomiting. The blood-brain barrier is much weake
rons in this region to detec the presen
that enters the circulatory system from
init vomiting, Ihe organism is ey tl
ch before it cases too much damage

onstrates that a barrir exits peta
ithe cellsofthe

places the ha

expelled fom the so

INTERIM SUMMARY

Cells of the Nervous System
Newons are the most important cl ofthe nervous tem. The central nervous system
(ENS includes the brain and spina cord the peripheral nervous stem (PS) includes nes,
and some sensory organs.

Neurons hate four principal pas: soma (ll body, dendites, axon, and terminal
‘button. hey communicate by means of synapse. located at the ends ofthe ons. When

Copa na ot 2007

Eros
O

node of Ranier ae A
on baer act ige
rennen.
rope The sate oo
(asco pons and

Sn vs post e
ea posteas e) à
aa mias

52. BIE cuates 2: scr ns rc. Col ess Sem rr ablorgmancomcrsonse

ofthe action pote

an action potential traves down an akon he terminal buttons secrete à chemi th
has ether an excitatory or an inhibitory effect onthe neuron with which it communicates,
The interactions of reus of neuron wth her excatory and inhibitory synapses, ae fe
spon or al of our perceptions, memories, thoughts, and behavior

Neurons contain a quantity o der cytoplas, enclosed in a membrane, Embedded in
the membrane are protein molecules that hve special functions, uch a the transpor of
particular substances int and aut ofthe cell The nudeus contin the genetic informa:
Aion there forthe ll the proteins that the body can make. Micrtubuls and other
‘tein ments compose the cytoskeleton and help to transpor chemical from place to
‘lice Mitochondria sere as the location for most ofthe chemical reaction tough which
the cal extras energy from nutren

"Neurons in the central nervous system ae supported by al cls Within the CNS, as
noce provide the primary support and also remove ders and form sar tue in the
‘event of issue damage. Oligodendrocytes form myelin the substance that insulates ans,
and aio support unmyelinated axons Microglia re phagocytes tat sere asthe represen
Fate ofthe immune system, Within the PAS, support and myelin are provides bythe
‘Seman cls

In most organs, molecules fret move between the blood within the capilaries
‘that serve them and the extracelular Mid that Baths their cl. The molecules
pas through gas between the cal that line the capilar. The wal ofthe cps
‘of the CNS lack these gaps and ths form a barr between the blood and the bran
As a consequence, fewer substances an entero leave the brain acros the blood-brain

THOUGHT QUESTION
he fact that the mitochondria in our als were originally micoorgaisms that infected
our very remote ancestors points out tht evolution cn ive iterations between
‘oor more species. Many species have other organi living inside them in fc the
bacteria in our intestines are necessary fr our good heath Some microorganisms can
exchange genetic information, 50 adaptive muttens developed in one peces can be
‘opted by another posible that some of the features ofthe all of our nervous
tem ere queste to our ancestors from other species?

“Thisscction describes the nature of communication ina newron—the ay an
tion potential sent rom the cell boy down the axon to the terminal buttons,
forming them 1 release some neurotransmiter. The details of synaptic
teansmision-—the communication between neurons be described in the next
Section. As we will se inthis section, an ation potential consists fa serie falter
alo membrane ofthe aon that permit various substances to move betwee

{hc imterior ofthe axon and the fd surroundingh. These exchanges produce el
Ac currents (See Animation 22, The Action Potential,

Neural Communication: An Overview

"Before begin my discusion ofthe action potential le tcp back and see how ne
to produce a useful behaior. We begin by examining a simple as

ola withdrawal ell. In the next

mule

he points

53. axon. The sensory neon inthis example detects painful trl
‘When its dendrites ae nl hous sinus (sich as contact with a hot
objec) it sends messages down the axon tothe terminal buttons which are located
nthe spinal cod. (You wll recognize this cell asa unipolar neuron see Figure 210.)
The terminal bution of te sensory neuron release a neurotransmitter hat excites
the interneuron, causing i to send messages down its axon, The ter

ofthe rom release neurotransmiter that excites the

nal ut
transmiten e cells contac,
object. (Sec Figure 2.10)

‘So ar alla the synapses have had excitatory fleets, Now et ws complicate mat
tersa bit 0 see the effet of inhibitory mapas. Suppose yon have removed a hot
casero from the oven, As ou stat walking ver tothe able to put it down. the heat
bginsto penetrate the rather thin potholders you are using. The pain eased bythe

ot caserolewigges a withdraal reflex that tends to make yt drop i. Yet you
age to keep hold of tong table and put down. What pre
your viral reflex rom making ou drop the casserole on the Moor?
"The pain from the hot caseroe increases the activiy of excitatory sap on
motor neurons, which tends to case the hand o pil ana fom the carole
excitation isconnterated by mb, plied by another soc: the
Iain. The brain contains neural circuits that recognize what a distr it would be i
you cropped the casserole on the Moor These neural circuits send information othe
Spinal cord that prevents the withdrawal reflex from making you drop the dish

Figure 211 shows reaches the spinal cord Asyon can see
an axon from ane spinal cord, where ts terminal but
tone form synapses with an inhibitory interneuron. When the neuron in the bra
becomes active, ite terminal buttons excite this inhibitory in
terneuton releases an inhibitory
motor neuron, Blocking the wi
à contes between two compe
it (See Figure 2.11)

motor neuron release their ncuro-
ting the hand o move ay from the ho

curetransnter, which draws the aci ol the
dana reflex This circuit provides an example of
tenvdencies to drop the casero and

Attalo ata urn ernus span una

pa ua
==
oe a oo
y mar

54. 3 eee sr ablongman onieronte

‘here finition. btn gna ang from the ban can prevent he witha el
‘om ang te person to op he assole

= mm
= =
Measuring Electrical Potentials of Axons

membrane poten! os

cane the ele

Ton
pair of electrodes Electrodes are electrical cond
Ac to enter or lave a medium. One of the electrodes I a

charges generated y an axon we wil need to se a
tors that pride a path Tor cle
‘ae te ne no ple wire that we

ei ode dose | Place e use to record the message from the
= on, has tobe special, Because even a giant squid axon is raher smal we

the seawater, The other one, whi

Loaves À mien cece hat will record he membrane potential without camaging the a

Pre tony | To do so we use a microelectrode

Foren tesa ur A microelectrode simply a very small elctode, which can be made of metal
men ete came | or glas. thi case we will rade of thin glas tubing, whic i heated and

rue ran down o an exceedingly fine point, ls th

resting pote! re men tiameter Because glas il no conduct elcticio he glas microelectrode filled.

Ser poe room | ita quid that conducseicrichy uch aa solution of potassium chloride
reta ay onto | Hai E

no posar pa ‘We place the wire electrodo in the seawater and incr the microctecrodo into
ieh nt a be | theaxon. (See Figure 2.12.) As soon as we do so, we discover that the inside ofthe
onus ann axon Is negatively charged with respect tothe cuties the difference in change be

55. Potential energy tapped and converted int radiant ev
eng (light). (See Figure 2.124) Similar, i we conn
eleetrodes—one Inside the axon and one outside it

toa very sensitive voltmeter we wll convert the potential
‘energy o movement ofthe meto smeedie. OF conse the
P
very weak in compari

ith cha of a aight tery

This deve, Be soler measures voages but lao
Produces a record of thse ulages graphing them 25
function of tne, Thee raphe are did on are.

much like the one found in television. The vertical ans
represents voltage, and the horizontal axis represents
die going rors elt right

‘Once we imert our microclctrode into the axon, the
(ociloscope draws straight horizontal lie t-70 mas
Tang asthe axon ls not disturbed. This electrical change
across the membrane is called the resting potential the
membrane potential measured while th

Now Les isturb the reting potential and sce what
app
trial simulator that allows us o alter the membrane

a vol), Thus, the inside o

ic is called the membrane potential, The term ptr
yin this case, electrical energy, For exam
nected to an eleticl circuit has a Jena!
cc a Tight bulbo he terminas he

Meng ee urge. (A volimete detecting the charge

a NY

Gm ©
QUE ‘ate

56. MIT. tot 2: Sci an uncon of Cet of he Neos Sem wor ablongmancomicartonte

potential at a specific location. (See Figure 2.) The stimulator can pass current
through another microclectrode that we have inserted ino the axon. Because the
inside ofthe axon ls nogaine, a poste charge applied tothe inside ofthe mem
roues a depolarization That, it takes away some of the electrical charge
‘across the membrane wear the electrode, yeducing the membrane pote
Lets sce what happens to an axon when we artificially change the membrane po-
tential at one point. Figure 2.14 shows a graph dram by an oxclloscope hat has
Pen monitoring the tics of brief depolarizing stimu The graphs ofthe effects
ofthese separate stimuli are superimposed on the same drawing wo that we can co
pare them, We deliver series of depolarizing si
tas (number 1) and gradually increasing
¿lepolries the membrane pot le
ization number 4 the membrane potential sudden revere si, o thatthe inside
becomes fast (and the ouside becomes negaie), The m potential
quick returns to normal, but is it overshoot the ming +
perpolarized—more polarize
cons). (See Figure 2.14)
id rever ofthe membrane potential scale the
onstttesthe message carried by the axon from the eel bods o
riggers an action potential which was
achieved only by depolarzing shock number = call the threshold oF exc

cir strength. Each stim
wore. Finally after we present depolar-

“he mean by which an aon cn be stated we ts nacion potent Terenas would be wen on an

nene potent beng recorded

re om o

L
FR

ñ
&

rent

a pense
ss me see)

ou

57. ommneatan vi

‘The Membrane Potential: Balance of Two Forces

derstand what causes the action potential to occur, we mus first understan
reasons for I potential. As we wile, thi eect
‘al charge isthe result of balance between two opposing forces difusión al elec
rosa pressure

The Force of Diffusion

much longer
mehr even veer even ¿Po ome isthe I
id. The process whereby molecules distribute themselves evenly throughout the
‘medium in which they ate dis scaled diffusion.

When there re no forces or barriers o preven them from doing o, molecules

eue are constant in mot

their rate of mone
ero [OK (ke TF] do mote
‘ules cease their random movement. At al ther temperatures they mone aba
colliding and veering of indifferent directions, thus pushing one another aay,
‘The result ofthese collisions in the example of gar and water to force sugar mo
ecules upward (and to force water molecules downward anay from the regions in
which they are most concentrated

temperature. Ona abot

The Force of Electrostatic Pressure

When some substances are disoled in water, they split int wo parts each with
an opposing electrical charge. Substances wth this propery are called electrolytes;
he charged particles into which they decompose are called fons. ons are of wo be.
Si pes Cations have a poste charge, and ions have a negathe charge. For ex:
Ample, when sodium chloride (NaCl 4 ter, many of the
‘molecules split into sodium cations (Na?) and chloride anions (C1). ind that the
‘cases way to Keep the terms cation and anion sa
sign asa ross, and remember the super

As ou have undoubtedly le
ch other (+ repels +, and = repels =), but particles with different changes are a
tracted to cach où = tra), This anions repel anions, cations repel
‘ations, but anions and cations atract cach other The force exerted by this atra
tion or repulsion scale eleetrotaie pressure. Jus as th force of difusion menes.
‘molecules from regions of high concentration to regions of foe concentration ele
rosa pressure moves ions from place to place: Cations ae push ana rom re
sions with an exces of cations. and anions are pushed away from regions with an
‘exces of anions,

ons in the Extracellular and Intracellular Fluid

The id i id surrounding them (extra
«ros prose

‘contributed by these ions ge se othe membrane potential. Because the membrane

potential is produced by a balance between the forces of diision and electrostatic

prestres, understanding what produces hi

entration ofthe varon io i the extrac

deparan hin
pote face om loma
Piper tone
eave to e mala
"resido! exdaton The
‘ave ote narrar otro!
“tun Memento! mol
demora
age hs o
ene su a, or
lan A used moe tos
pére
deere Ope
lesa pressure De a
RE On om
Some parc rg e
excl id ss

58. MEE cure Src on oc em en mamans

Tee conato of ame important os ini and ute he euro and te fre acting on the

hence, they are abbreviated Na and K, respectively. Organic anions—negatvely
charged proteins and intermediate produce ofthe ces metabolic processes—are
inthe intracellular Mid. Although the other three ions are found in

inthe in

here it real hat he Mui that surrounds our cells similar to sea
is predominantly a solution of sa, NaCl. The primitive ancestors of our ells ved
ths the seater was heir extracel. Our extracelular fd
thus resembles seawater, ine by regulatory mechanisms hat
are described in €
Let us consider exam sion a
liste pressure exerted on cach and reasoning why each located where its
there:

son tendeto push out of the € cell charged pos
inch with re
inside. Thus, the two opposing forces balance, a
where hey are. (See Figure 2.5.)
“The chloride ion Cris in greatest conce
Aiision pushes this on inward, However, because the
y charged, electrostatic presu pushes
forces balance cach other (See Figure 2.18)
Te sodium on Na iso
Cri past
ion is pony charged. Therefore, electrostatic prewsure does no present N

potascum fons end to roma

side ofthe axon is mega
rd. gain, no opposing,

59. be na charge ide he AN EE
‘on ata Na Ge Pe 2.139

How can Na’ remain in greatest concentration in the * 4m pra tapout inthe cl mentar,

‘extracel id, despite the fat that both forces (di
fusion and electro pressure) tend to
The answer fthis Another force, prone bythe sa
ass pump continuously pushes Na” ont of the axon
The sodiumporasium pump consists of a lange number
of protein molecules embeded in the mern
boy energy provided by molecules of ATP prod
he mitochondria, These molecules, known as sodium.
potassium transporters, exchange Na for K" pus
fhe sodium ions out for cry two potassium ion they
pus in. (See Figur 2.16)

Because dhe membrane not very permeable to Na
soctivm-potasinm transporters very effectively keep the
intracellular concentration of Na low. By
into the cell, they alo produce a
tracellular concentration of K
proximately 100 times more permeable wo Kha
othe increase sig
the proces of neu
very import
sodlumvepotasum pump use considera
40 percent ofa neuron’s metabolic resources are used to
‘operate them. Neurons, muscle cell, gain fact, most cells a dhe boy have
sodiumporasum transporter in their membrane

But as we will sec when we study
icon ter in this lap

The Action Potential

As mesa he

arcs ofboth ion and electrostatic pressure tend to push Nat
imo the cell However, he membrane not very permeable to this on, and sodium
Potasium transporters continuons pump ont Na", Keeping the intracelular level
Of Na lo: But imagine what would happen ifthe membrane sudden] became per
Imeableta Na. The forces of dif would ene Na 40
rush imo the ell This sudden intl (nfl) of postie charged fons would das
tically change the membrane potential. Indeed, experiment have shown that this
mechanism is precisely what causes the action potenti À brief increase
ality ofthe membrane wo Na? allowing these ons ta rsh into
realy followed by a transient increase in ıhe permeability ofthe
(allowing these ons o rush out of the cll), What e resp
sient increases in permeability?
fone ype of protein molecule embedded
camporter—actvey pump sd
o 4. Another pe of protein molecule provides an open
‘or leave the cell These molecules provide fon chan-
‘open or close Whe
ow though the pore and thus can enter or
(See Figure 2.17) Newel membranes contain many tonsa of k

and electrostatic pres

he membrane—
ot ofthe cell and

permit ions te
passages ("pores that
ar pe of fon can

ane. (There are one milion square
à patch of axonal membrane the ize of.
lowercase letter 0" inthis book would contain several hundred million soi
channels) Each sodium channel can ani yp o 100 million ions per second when

cum potasium rampe
lon channel A pc o.

60. BIZ cin 2 Socie a functons of Celso ens Stem wor ablongman comen

she permeabiliyofan

et! moment is deter

res tha are ope
nbered paragraphs describe the

‘he movements fons ng te acon poten Te daga
Mine op Dom the opera ol som cannes atthe meld er ofa
cation er ecto conan atthe pea of he ac

potenti and thew ser when he membrane potent

the numbers of the paragraphs that follow. (See Figure
218)

1. Assoon athe

c. Ti

opening of
m ofthe membrane po-
tential (depolarization); they open at the point a
Which an action potential begins the threshold of
{ccitation, Because these channels are opened by

‘membrane potent, they are called

‘olla dependent ion channels. The influx

Thus they begin o open
anche

shout the time the action potential reaches its
peak (in appronimately mse) thesia ha
Become cto channels become blocked and
Treat eau Cannot open aga ‘membrane once more
Settee LEE Teaches he resting penal A this me

nl

61. 4. By now: the voltage dependent potassiam ch
teng ane. Ati me, the inside o he
axom i patel charged, so K' is driven onto the cell y illusion and by eee
iros pressure, This oto of cations causes the membrane potential o se
turn toward its normal vale” A docs so, the potassium channels begin 10
le ga

3. Once the membrane potential returns to normal, dhe potassium channels are
“sed, and no more potasium leaves the cell, A around this time, he odian

ans reset so that another depolarization can case them t open again,
membrane actually onershoos its resting ale (70 mV) and only gr

ally returns to normal. The accumulation of ions outside the membrane ae

responsible fortis temporary hyperpolariation, The extra jonsK som dius

na and the membrane potential returns to~70 mV, Esentaly si

rns in the membrane are open

porter,
enough that

I message down the axon or am

Shunt ana ra ot
tornone la Te ce

‘tution of the ation potenti To study this phe. Cndacion fe action potenti Wen an actin potent tiger.

nomenon, we an make we ofthe giant sid
axon, We attach an electrical
<lectrode at one end of à

lavor wan ee
axon and place

rctrodes, one alter the other Thus, we see

ls cn poeta condo down he Depor
size, (See Figure 2.19.) |
Thi experimen cales a as of
the argus TL
nied do the ao o An acon po \

tential als 1
rowing or diminishing. Wh
{al reaches point where the aon br

ns the same sz, without

splits

toes not mina in ie, An avon wll

Iie temas unimos tos down te aon The pee ol
«cout an be lalate hor the din between e td he

recording électrodes attached to oxilloscopes,
A ere distances rom the sin a
ode, Then we

he endl ofthe axon and rigger an a 7
a. We record the

62. BETEN caren 2: isc tución of Celso eens Sion wr ablongmancon/eatonte

ni an action potential in either direction, or even in
rections i ti started in the middle of the axons
Tenth. However, because ation potentials in ing animals
away tart at the end attached to the soma, axons normally
‘carry ones tai

AS ou kno the strength of a muscular contraction ca
sary from very weak over orcful and the strength of ati
As an vary from barely detectable to very intense. We know

Isin axons controls the
represented intensity

‘of a physical stimula. But ifthe ation potential san aor

Tm — none event, how can iio hat ca vary in
uous Fashion? The answer is simple: À single action

Song ss

son ET Ab information is represented by an son's ato fing (

on

Stman SEA tion, and a strong stimulus (such as a bright light) causes

ata The pence a a:

‘ator conduction con
notation ps me
Rn othe ex.

‘the bai element of informati

this context, fring eters tothe production of action poten

on tials) A high rate of Fring causes a wrong muscular contrac:

that serve the exes. Tas, the al
‘ornone la ssupplemented by the rate lave (See Figure 2.20)
bt the sales or nervous stems are mye

nate segments ofthe avons ae conered bya min sheath produced by the oigo
endvocytesot the CNS or the Schwan cel ole PNS, These agents are separated
by portions o naked xin the nodes of Ranvier Condition of ah ation potential i
A melinate axon à soma different rom condition in an myelinated axon,

‘Scan cells and the oigodendrocyte of the CNS wrap tightly around dl
axon, les ssurable extracellular aid between them and the axon. The
‘only place where amyelnated axon comes into contact with the extracellular Mid
ita mode of Ranvier, where the axon I naked. In dhe myelinated areas there can be
th inward How of Na when the sodium channels open, because there sno extra
car sodium, The axon conduct the electrical disturbance from the action po
mal to the next node of Ranier. The disturbance is conducted passively he way

"electrical signal conducted though an insulated cable, The disturbance gets
“Salle sit pases don the avon, but il large enough to trigger a new ation
potential atthe next node. The action potential ges retriggered or repeated, atch
Mode of Ranvier, and the electrical disturbance tha rests is conducted along the
mselinated area to he next node, Such conduction, hopping from nove to node.
Called salatory conduction, from the Latin sala, io dance.” (See Figure 2.21.)

Salatory conduction confers two advantages. The fists economic. Sodium
pos transporters must expend energy o get rd of the excess Na that enters
the axon during the action potential. Sod porters mus helo:
‘ete along an unmyelinated axon because Na" enters everyahere. However be
‘Case Nav ean enter a myelinated axon only atthe nodes of Raver much less gets

sequent; much les has o be pumped out again. Therefore, a meli
rate axon expends much les energy 10 ma balance.

“The second advantage so myelin speed. Conduction of an ation potential is
faster ina myelinated axon because the transmission between the nodes very fa
Increased speed enables an animal to reat Ester a eal) to dink faster
‘One ofthe ways to increase the speed of conduction isto increase ie, Because its
large, the unmyelinated squid axon, with diameter of 300 jun, achieves a con:
“ction velocity of approximately 33 mc (meters per second). However a mic
hated cat axon achieve the Same speed wih a diameter of a mere 6pm, The fastest
meine axon, 20 um in diameter, can conde action potentals ata speedy 120
trace, or 482 km/h Atha speed a signal one end fan axon o the
‘other without much delay

high ate offi

in, and cy

63. State conduction, Showing propagation an acon pote don a meinte

com

yin sean

as
es

Decremen Aton stot
Gén gens
ren sine an

INTERIM SUMMARY —

Communication Within a Neuron

haves The circuit responsible fr ti reflex consists of thre sets of neurons seta new.
1908 itereurens, and motor neuron The reflex can be suppressed when neurons athe
brain activate inhibitory interneurons that form synapses with te motor neurons.

"The message conducted down an axon called an action potential. The membranes of
cell ofthe body ar electrically charged, but only axons can produce ation potential.
‘he resing membrane potenti ocur because varour Ins ae located in ferent con
‘centrations in the fi nid and outside ne cl The extracelular fd ike seamate
‘ich in Na and Cr and the intalulr fui ich in K and various organic anions, de.

The cll membranes freely permeable to water, butts permesbilty to various ons
In particular Na and K°-is regulated by ion chan When the membrane potential a
Festin value (TO MU) the votage dependent sodium and pots channel ore dose,
The experiment with radioactive seawater showed us tht some Na continuous ess into.
the axon but promptly forced out ofthe cell again by the sum palm transporters
(which aso pump potassium into the axon) When an elect simulator deplarzes the
membrane of the axon so that ts potential reaches the thveshold of excitation, voltage:
dependent sodium channels open, and Na" rhe nto the cl driven by te fore of ait
fusion and by electrostatic pressure The entry ofthe poste charged ios further reduces
the membrane potential and indeed, causes to revere, s the imide becomes postive The
opening of the sodium channels s temporary; hey soon close again. The depolarization
caused y the influ of Na activates voltage dependent potarsum channels, and K eaves
‘the axon, traveling down its concentration gradient. This ef (outflon) of Ke qui
‘brings the membrane potential bak tts esting value

Because an action potential a given ara san allornone phenomenon. eutons ep
resent intensity by their ate of fring. The action potential normally begins at one end of
the ator, where the axon attaches tothe soma. The action potential waves continuously
‘own unmyelinated ans, remaining constant in size, uti reaches he terminal buttons,
(the non vides, an action potent continues down each branch) In myelinated axons
tons an low through the membrane oly a the nodes of Ranvier, because the axons are
‘covered everywhere ele with myelin, whieh oles them rom te extracel ut Tus,

64. BET cHarten 2: si aurons of Cl fe Neus Sten sr ablongman on/earonse

passage pote A

Somers ee
dudit ape Aston
premopue membrane ne
FETE sem ton
pesopape mets ve
smog et eo
se i) 5
ones

he action potential s conducted passively from one node of Ranvier tte net Men the
electrica message reaches à node vltge-dependent sodium channels open andthe action
‘potenti reaches ful strength again. Th mechonsm saves a considerable amount o energy
Because sodium potasium tramporters are not needed along the myerats portions the
tron, Salon conduction sao fate than conduction of action potential in une
ated on

THOUGHT QUESTION
“The evolution ofthe human ran, wi al ts comple, depended on many apparent
il mechanisms For example, hat ces had nt developed the aby to manulac-
‘ure myelin? Unmyelnated axons mus be very Large if they ac 1 transmit ation po»
tential apy, How big would the human brain have tobe if eligodendocytes didnot
produce myelin? Could he human brain swe know it have evolved without myelin?

now about the basic structure of neurons and the nature of the ac
itistime o describe the wa in which ne vate with
to gather

Sensory information, make plans a
The primary means of communica xro ds synaptic tans
transmision of messages from one neuron to another through à
ape As mes these message are carie by neurotransmiters, release br ter
‘minal buttons, These chemical diffuse across the ui led gap between the tr
Minal buttons and he membranes fc neurons with which they form synapses. As
Se wi sc in hissection,neurotranmites produce postsnapie potential brit
{cpolarvationsor hyperpolarizations-that increase or decrease the rate of fing of
the axon ofthe postsnaptie neuron.
Neurotrammites exert their effets on cell by attaching toa particular regio
‘of a receptor molecule called the binding ite. À molecule ofthe chemical fis into
the way a Ke its nto a tock: The shape ofthe binding site and she
shape ofthe molecule ofthe neurotransmiter are com
xtaches 0 à binding sit alle a igand, from ligar, o
nds, produced and released by nctrons But other chemicals found
in nature (primary in plant or in dhe poisonous venoms of animas) can serve as
ligando tor In alton, artificial ligand can be produced in the laboratory. These
chemical are discussed in Chapter, which deal with drugs and thei effects.

Structure of Synapses

Aa jou have already learn sions heen the terminal bu
the ends of the axonal bran neuron and the membrane of another.
Srnapnes can occur in three places on de soma, and on other axons
These synapses are referred tos axe, aumamati, and ont. Ad
Arie synapses can occur on the smooth surface of a dendrite or on dendri
pines small protrusions that std the dendrite of several types o Large
ithe brain. (See Figur 2.22)

Figure 228 rates a ymapsc The presynaptic membrane, locate at he end
‘of dhe terminal button, faces the postsynaptic membrane, located the
hat recches the message (he pmtynapirneuron), These two membranes
bother eros the snaptie left gap that are in ie from synapse to synapse but
ie usual around 20 nm wide: (A manometer (mn fa meter) The
Smapie cleft contains extracellular Mai, through which the neurotransmiter dí

65. Types tapes Axodndrti apes can cur on the smooth suc ofa end ton
eras Auer opis ocr on somatic membrane) Auto ap
“ont ol apis beeen to termal batons (9

Prorat
race Soma, ‘rar tc
sooo

O o © @

fuses. A meshwork of filaments cross the synaptic cleft and keep the presmaptic
and postsynaptic membranes in ligament. (See Figure 2.23.)
As you ight have noticed in Figure 2.28, the plas

eras ofa snap

66. BET sae 2 scien Freon of eho te Nanos St

Cnam onda ie tra

ono dependent
conejo on

When a

something happens i

ited jus

open. piling
Heise

the much
mately 5

es
en, a

Feature ofyopses andthe

à photograph rom a econ microcosmos
tion oa pp. omega sped fires are rape
‘ic ange pret mena tema

10 the release zone, the region from whic
inthe soma and ae 6
terminal button. (See Figure 223)
Iman electron micrograph
appears somewhat thicker
‘papi cess cate
presence of ncurotransmittrs inthe snap cl (Soc Figure 2.23)

ide
side the presynaptic membrane uses

crographs at ilusa
Very rapid event, taking only few milliseconds to occur, special procedures are
needed wo stop the ations

cal timed the nerve attached o an folate
a block of

1) Contact with the
sec or less. The ic held the compon
hey could be chemically stabilized

À shows a portion

nor
cc Animation 2.3 Smaps,

or ahiongman comarienée

ner is released, Snape
cd by fast aplastic transport to the

he postsynaptic membrane under the terminal button
1d more dese than the membrane elsewhere. This pot
presence of receptore—specalize protein molecules

Release of the Neurotransmitter

he smapic cet
fuser, 1077 I
process. Because

a. 1979) ob
release of

1 photomi-

dti can be studied. The expe
frog muscle and then dropped
copper that had been cooled to 4 K (approx
¡percooled metal rove the outer Laver of tse in
ofthe terminal bons in place uni

d examined with an elecron microscope, Fi
ros section: note the vesicles that appear

‘vith the presynaptic membrane, forming the shape of an omega (D

about the structure of smapses and release of the

Activation of Receptors

How do molecules of the ne

x produce ade
polarzaion or Iyperpolaizaion in the postsynaptic
‘et and ataching 1
‘molecules located “called
postsynaptic receptor. Once Did pay:
haptic receptors open neurotransmitierdependent ion
‘anne which permit he passage of specific ions into. oF
‘utof the cel Thus the presence of the neurotranamiter
the synaptic cleft allows particular fons o pas through
the membrane, changing the local membrane potential.
Neuronransmiters open ion channels by at leant two
erent methods, direct and indirect. The direct
is simple, so vil described first Figur
neurotransmiterdlependent on channel hate
‘vith ito binding ste, When a molecule of
priate neurotransmiter attaches to
‘Opens The formal name for this combination receptor ion
‘channel isan ionotrop receptor. (Soc Figure 2.25)
Tonotrapi receptors wee fis discorc inthe or
‘gan that produces electrical current in Tarp,
Fas here they occur in great number. (The electri ays
à fish that generates a powerful electrical current, not
Some kind of Star Wars weapon) These receptors, which

67. 0% Pi

aig te

or

the receptor actes a G pre it
brane next othe receptor. When ac

Postsynaptic Potentials

stab route oh i

68. DER con ron sce antros Cee nos sn

Bw a eeptor second mesenger reduced ha opens

rer ion hones

ES

Mode oneurransmiter Casen
‘tienes orgue al cat
neater ection

the chloride

‘of opening chloride chan

‘wor alongman comasene

characteristics of the postsynaptic recepors—in pari
lary the particular pp) on channel they open. In ere
parts he brain, particular neurone may bind
‘sith different pes of on channels, cach of which
have dillerent eect, (By analog.
‘open several different doors, wich op
event pes of rooms)

As Figure 227 shows, three major types of
tranamitercdepen

in the
0 06,
le figure epi onl di
recth activated (inotropic) ion channels, vou should re
‘ze that many ion channel are activated indirect, by
metabotropic receptors coupled to G prot

The neurotransmiterdlependent sodium channel is
the mow important source of excitatory postsynaptic po:
tential, AS we sa, sodium potasium trimporters keep
sod outside the el eating forthe forces of ion

decresaic pressure o puch iin, When sodhum char
nels ae open

Earlier, we saw that sodium-potasium 4
‘maintain a mal surplus of potassium ions inside the ci
{potassium channels open, some of these cations wil f

radio and leave the cell came K° à pon
tively charged, is outflow will hyperpoks

onc movements duro potnapt poten,

on oC eases
nanas
Lo

69. conmincston raso Novos ACER

tot membrane a the resting potential, nothing happens, because (as we sie
lier) the forces of ion and electrostatic presse bal for the chlo-
de jon. However

act of exc
Sil permit EE enter he cel The
{ental hack ot normal resting condition. Thus the op
sees to neutralize EPSPS (See Figure 2.27)

re por
ning Mori channels

Termination of Postsynaptic Potentials Salter reset Sa
Postsymaptic potentials are brief depolarizatio rations caused by the ee

entre pups cat

Ionen postman poten

hors) Sse pee
potatoe me nee

accion of post
pt brie by so mes

terminal buon contains special ramporte molecules that raw on the cellscneng | Meran ot opacas
reserves to force molecules of from the synaptic cleft hc | o restent

arn the terminal buon rel | Mula er are
mount of neuen mote spac co and en lc | PR
ing the posiymapic receptor only abre expone lo he nctroramnte (Sec | mem scudo de

Figure 2.28) osu pte

ERIGUNG 22805 AAA

Reuptate Molle nsrtraneminr rt ha bee rias note rap ft
nord bak nto te terna Btn.

‘ered tome ‘eras ae

70. ETI aren 2: sico an Functions of Ces othe Nervous System worm ablongman com/caiionbe

sr
Ares
re
rene
en
SS

Pepper
caottetecene no
prend
Create

ation De ro
orten Acer ml
nad aro.

jane that denroys ec

Transmision at
‘smapees on muscle fibers and at some smapsc between neurons in the sentra ner
‘oun stem ie mediated by ACh, Pompe potential produced by ACh are hor
lived because the pontsmaptie membrane at these smapses con
«alle acetycholinesterase (ACHE). ACHE destroys ACH Dy
and acetate, Because nether of these subtance capable of ac

tating postsynaptic receptors, the poxtsmsptic potentials terminated once the
molecules of ACH are broken apart. ACRE i an extremely energetic dexroner of

one molecule of ACHE will chop apart more than five thousand molecules of
ach second

Effects of Postsynaptic Potentials:
Neural Integration

We ave seen how neuro

reconnected by means ofsgnapses. how action po-
al iger the release of neuroranamiers and how these chemical initiate ex,
‘tatory of inhibitory postsnapuie potentials. Esctatry postsynaptic potentials
increase the likelihood thatthe postsynaptic neuron vil ir: inhibitory possuap-
tic potentials decrease this ikelood. (Remember, ring” relersto the occurrence
‘of an action potential) Thus, the rate at which an axon tess determined by the
relative acts ofthe excitatory and inhibitory symapaes on the soma and dendrites
‘ofthat cll. here are no active excitatory smapas orf the act ol inhibitory
synapses is particularly high, that rate could be lose 10 zero.

Tet us look atthe elements ofthis proces. (See Animation 24, Postomapúic Po.
ile) The interaction of the effects of exciatory and inhibitory smapses on a
particular neuron is called neural integration. Untapatio means “to make whole.”
Inthe sense of combining two or more fi illustrates the effets
of excitatory and inkibitory smapses on a postsmapaie neuron. Figure 229(a)
Shows what happens when several excitatory aptes become act. The release of

fe heatotransntter produces depolarizing EPSPsin the dendrites ofthe newton.
These EPSPs (represented in red) are thet transmite down the dendrites and
acros the soma to the axon hill located tthe base ofthe axon I the depot
ination il strong enough when it reaches this pont, the axon will ire, (See Fig:
sre 2.290)

Now lets consider wh
also beco

wold happen if atthe same ie,
ace, Inhibitory postsmpál potentials are hype
bring the membrane potential aay from the threshold of excitation. Ths, they
dto cancel the elects of excitatory postsynaptic potentials. (Sce Figure 2.29.)
The rate at which a ncuron fire controlled by he relative activity ofthe exc
ory anal apscson is dendrites and soma. I the activity of excitatory
synapses goes up, the rate of Firing will go up. If the activi of inhibitory synapse
poes up the rate of ring wil go down

Autoreceptors

Postsmapi receptors detect the pres rin the synaptic cleft
nd inte exchatory or inhibitory postsynaptic potentas. But the postsmapc
brane isnot dhe only location of receptors that respond o ncurotrans

Many neurons also passes receptors that respond tothe neurotranam

emits clase, called auoreoeptors

71. ural integration) several ectatay apresar acte a the same tn, he ESP they
produce how nr) sonate a hy trate! omar e mo, ae na re Wares
Ent synapses oe ete the some me the PP they prota ou Bu) Sesh he
A fe SP and prevent the no Wom ig.

IPPs courte EPSPs
‘son pan à no
tages anon

o o

Auoreceptors can be locmed on the membrane of any part ofthe cell, but in
this discussion we will consider those located on he terminal button. In most eases
these autoreceptors do not control on channel. Thus, when simulaed bya mole:
‘ule of the neurotransmiter, autorecepors do not produce changes in
brane potential of the terminal button Instead, hey contol internal processes,
including the synthesis and release of the neurotansmiter. (As you may have
_guesed, autoreceptors are metabotropic the control they exer on these process
‘accomplished through G proteins and second messengers) In most cases the ef.
fects ‚io activation are inhibitors that the presence ofthe neuro:
«cular fl in the vicinity ofthe neuron cave a decrease
transit. Mon investigators helene

Production and release: if not enough ls released
lease go up

Axoaxonic Synapses

Aste sein Figure 222, the central nervous system contains thrce types of snaps
Ai of the isto types axodendrtie and axowomatic smapses, cies pot
ition. The third type, axcaxonic smapses does not con:

of thea oymapacs alters the

nal butons of the postsynaptic

72. BIZ char 2: sc a ution of Cl tn Nes Sten sr ablongman on/caronte

creator det he mount ol proa les by

¡ses can produce presynaptic modul

‘ion: presynaptic inhibition or presynaptic faiiation,
As yout ko, the release of a neurotransmnier by a
termina button isi n action potential, Nor

mall; a particular terminal bution releases a fised
‘mount ol neurotransmiter each time an action pote
ial arives, However the release of neurotransmitter ca
bbe modulate by the activity of axcaonie synapse.
act ofthe asoaxonie sap decreases the release 0

ict i called presynaptic in-
"bon. Ii increases the release, is called presynaptic
facilitation. (See Figure 230)

Nonsynaptic Communication:
Neuromodulators and
Hormones

Neurotransmitter are released by terminal buttons of
detected by receptor in the membran
‘of another cell located a very short dis
‘communication at each synapse pris
tors are chemicals released by neu
and ae dispersed more widely than ae
Neuromodulators are sccreted in larger amounts and di
fie for longer distances, modulating the activity of man
sin a particular part of the bran. For example,
‘neuromorlatrsalfect general behavoral ates such as
es, and sensitiv pain, Mos retromodulators are composed of
e described in Chapter 1
‘Mos hormones are produced in cells located in the endocrine glands (from
Greek edo, Within and rien, "wo secret”), Others are produced by spe
cells located in various organs, such asthe stomach, the intestines, the hide), and
‘he brain, Cells that secrete hormones else these
Mic The hormones arc then distributed to the
stream Hormones affect the act of cll (including neurons) that con
alized receptors located ether on the surface of their membrane or decp within
thei nucle, Cells that contain receptor fora particular hormone ae referred to
target ells or that hormone; only these cell respond o presence, Many neurons
in hormone receptor cable to aec behavior by simula
receptors and chan se neurons. For example, sex hor.
none, testosterone, increases the aggressiveness ol most male mana

neurons and a

INTERIM SUMMARY

Communication Between Neurons
Synapses consi of junctions between the terminal buttons of ane neuron and the men-
‘rane usualy the somat or dendritic membrane another When an action potential
'Svansmited down an axon, the terminal buttons tthe end release a neurotansmite, à
(hemical that produces either depolarizations (ESP) or hyperolariaios (SPs) of the
postsynaptiemembane.Theratof ring ofthe axon ofthe postsynaptic els determined

73. bythe lative activity ofthe excitatory and inhibitory synapseson the membrane of is den
dites and soma—a phenomenon known as neva integration

Terminal buttons contains synaptic veces most cluster around the release zone of
the presynaptic membrane When an action potential reaches terminal button. i causes
‘the release ofthe neuotransmiter: Synaptic ess that ae located atthe release zone
‘ue with the presynaptic membrane of he terminal button, beak open, and reiste ter,
nerotransmiter int the synaptic det

he actuation of postsynaptic receptors by molecules f a neurtransmiter causes ne
rouansmitter-dependent on channe to open, resulting in postsynaptic potenti.
lonotrpicreeptors contain ion channels, which ae ect opened when aigand attaches
the binding site Metabotropc receptors are linked to G proteins which, when activated,
open on channels by producing a chemical called a second messenger.

he nature ofthe postsynaptic potential depends on the typeof fon channel that is
‘pened by the postsynaptic receptors at a particular synapse Echatry postsynaptic po
til ocur when Na enters the el: inhibitory postsynaptic potenti are produced by
‘the opening of K channel or Cr chants

Postsnaptie potenti ae normal brie. They ae terminated by two means. The most
common mechanism is reuptake: revival of molecules ofthe neurtranmiter rom the
apt deft by means of transporters located in the presynaptic membrane, which trans
‘or the molecule back into the cyoplm. Aceychoine is deactivated by the enzyme
deabjchlinesterase

The presynaptic membrane, as wells the postsynaptic membrane, contains receptor
‘that detect the presence of a neurotransmitter. Presynaptic receptors, abo caled autre
‘ceptors, monitor the quantity of neurtranmter hata neuron retesses and apparent
‘regulate the amount that ynthaied or lasted, Axoanon yrapes produce prennap-
inhibition or presynaptic acai, reducing or enhancing the amount of nerotrans

Newromedulators and hormones, like newretansmitters, act on all by attaching to
the binding stes of receptors and inating electrical or chemical changes in these cel,
However, whereas the action of neufotrasmites is localized, neuromodulators and hr
mones have much more widespread ees

THOUGHT QUESTIONS.

1 wy does ynaptietransmision involv the release of chemical? Diet electrical
<oupling of neurons str spl, why do our neurons not use it more ete
sively? (A ny percentage of synaptic connections In the human ran do uo electr
‘al coupling) Normally, nature ves he simples means posable 10 gen en, 30
‘there must be some advantages to chemical transmision What d you thik hey

2. Comider he contol ofthe withdrawal ree ilustrated in Figure 2.1. Could you
design a cu sing electra synapses that would accomplish the same tasks?

oreyapc niin Th
nettes
copain
Sonnet os
recrear sty
mea at
Lee
ISO a voue gd 2
at cs on ada
docti nd Ad nt

newer spot
‘simon ooh at

PIL
Myasthenia Gravis
“Amir kath nn eee
o a ibid

‘osimle” sea. "No, mao you Katy dhappentmert. "Youve a tata lista las logar”
art eue but now we know Wat condon called myesthenia gas The Inde, ar she was taking, Kat fet

74. BEC cHarTen 2: soucie ad funcions of Celis ofthe Nenous System wre ablongman com/carson6e

has weakening, and heat down choline (ACH and terminates the pst eue in which the immune tem a

oan rap paentas it produces By dence” as and desrop many of the pans
sten gras mas rt described ing ACHE phosigmine gretyin- AG receptors, hich re neces for

‘in 1672 Thomas Wills an Eng reses prolongs the effec of ACA smapl anim.

Ban: The term tal means on te possymapi membrane. Ths” Recent restore hav suceeded

grave me weakness" Kisnota __ Iereaesihesrngthofsmaptitrans in developing an animal made of MG

ery common orde but mos experts mision at he syopses on mues and An animal modela diese that can be
oler that may sem mier everesthe fects rare (Chaptr4 produced in bortory animals nd hat

than Kathys of oure—ge undog: Wilsaymor about bth cuareand_ cosy resembles human dene. The
rowed. Kans deste med her phnotigmine) ‘ure ofthe te an then be tu
Fac neck am, ond rank moses but Or Walker esone that ied and pole extent or ars can
sometimes ny eye mies alo: pngongmin reve he effects of esd nth cas di ro

vale, Before the 18904 Kathy would rare poloning pepa moni ao duced y extracting Achrceptar pro.

ase became bedridden and astres e symptoms ol master tea rom etc ys Torpedo) adi
Fay have edwithinate rai She di andit uns jecing into laboratory anal. The
eo. probabiyofpneumonia ring mate ofa ew minutes Subsequent, anima immune stems become ses
Tom duty in breathing andcough>_pharmaceta companies score dt the protein and develop at
Ing But fortunate Katyn futures rugs tha could be ake rally and bodies that tack the own Achrecp-
not ok The couse of myasheia tat produced ingesting effects. tr The animal exhibit he same
‘favs iswel understood. andincanbe Nowadays an injectable drug used to muscular atgably sow by people
treated, no cre (make the agro and an orl og WI MG, and hey become stronger af

Thehalimarkof myasthenia gravis ued teat {ecreceinganijetion of ug sch
‘angbi That's patient hs reaon- Hesse tuned the eHorsto phortigine
able sent en rs ut becomes understanding the cause ol master One prom eu hat has
‘ery eat tr moving fra te ra OC. hey made tear interes emerge rom su ith e anima
‘ie For many yeu rather have eg ebenations Fist people wih MG model of MG se nding tat aan
ae hat ne mess cu in the ul had tus roer abnormal Ma immune tem canbe dese
maps on the maces potinthener. ein thei thymus gland te gland eds that it wl ot produce antibod
aus tem othe muses themes. os eme hei Symptoms often got ls at estoy ACh receptors. 1
An he te nimteeth comun a phys ete Rats neurologist might ee AChreceptor proteins are modified and
‘an placed lecrodeson the shin OT a ommand hat is tp be taken) sec then ited nt laboratory animal,
[enon with mataria gravis ond ele: ond) merci examination of therimmune ster deep an at
‘aly mate rare losing toa taken rom the muss o MG patients body gant the red poten. Ths
muse mue concis ch tie showed damage locales to the region antibody does not attack the animal?
Pa imusted the neve but the on around he maps and thisregion own ACh receptors Lats if they aro
cion became progresa weaker, showed anifiteion of white load ganthe pure AGrcept rote
However when he place the lcrdes cal Thee two fc suggested tht the they donot develop MG. Appar
above the mule and stimulated mmunesstem as moed white te pure poten bso ml 1 he one
techy the contactor showed nosigns blood ells are responsible or thei. 10 MN the arial were pews
‘of fatigue Later wth the development mune reaction, an the thymus lands sented that the inmune stem does
‘ot tecmiqesof leia recording e- ane ofthe sources ofthese cls rot bother to produce arate a
{arcu found thatthe action poten” infact MG an autoimmune di dy Parhap a vaccine con be deve:
il in e never of people wth myat- esse Normally the immune rem pro oped that canbe ued to are MG in
thera gravis were completely normal. tects om necios by beng ale sar stage by inducing the pesan
nant condicion and mur contac: for protein that are present on vad immune system t produce the hares
Von were normal then he problem Pad ing mirorganims The immuneptem ario) rather tan the ae hate
tolein he gmap Produces antibodies thatatack these tacks chaine receptors

In 1934 Dr Mary er emarked_ foreign poten, ad the miroorgan Even with he drugs ar are a
thatthe impos of myasthenia ras mare iles However sometimes the able o ins today, myarhenia
resembled he les faute, apo inmune stem makes mistake and favs eas sous dense The
son ot ica neral varsnision at becomessenize agaist one ofthe rugs donot estore a persons strength
{he agus on muss The antidote proteins hat are normaly present in 1 OIL and he an have serios

or cuar posaing war sg ed ourbodes rence have found, sd eects Dt the progres made in
piynortigmie whic echte ac. the blood of pats with MG cotans thelaberatry in cart year gies

Cholmestease ACHE, Asyaulamedin abodes agunt the protein that hope Jr brighter future fo people
thishapt ACME isan enzyme hat e- males up aceyholie receptor Mus, Ike Kay
‘roy the neurtranimiter set mana grav an autommune di

75. Supera ie MT

‘CELLS OF THE NERVOUS SYSTEM or inbibiory effects on the postynaptic neuron
These effects increase or decrease the rat at which
nal buttons. Crew of imereonnected son o the posta neuron sd action po
ne responsible forthe functions performed by the es do 1 terminal batons
serous tem, Neon ae sup by ls and 4 When an action potential aches the end of an axon,
by Schwann cell, which provide myelin beato, le some maple vesicles to release a neuro
Veh ee ul Wr ena Te amir ino the synaptic ieh. Moleces ol
bod -betin Bari helps to regulate the chemical rotransmiter attach themsehes to receptors
tien ine bal e possmapic membrane
5. When thes become acta y molecules of he neu
ver postgmapl receptor produce either
Suede mt iO excitatory or inhibitory possmapii potentials by
opening volageconwoled sodium, potasium. or
Chloride on channels
6. The powssnaptic potenti terminated by the de
rucion of the neurotransmitter or by i euptae
ino the terminal button
7, Antoreceptor help to regule the amon
ver that released
8. Axomvonic saps cons of junctions betwee
nal buttons Release of neuotransmiter bythe
first terminal Button increases or decreases th
amount of er released by the cond,
COMMUNICATION BETWEEN NEURONS 9. Neuromodulators and hormones have act
cable the pre

[Neurons havea soma, dendrites a axon, an

2. The action potential occurs when the membran
tential of an axon reaches the threshold of exctato
Although the action potential electrical, is cad
by the flow of sodium and potassium ions through
voltagedependent ion channels in the me
Salttory conduction, which takes place à
nated ason, i faster and more elie

‘duction in unmyelinated axons

unica by means of snapses, which ar hose of newroranamiters They bind with and
apticneuron to produce excitatory activate receptor on thet target cell

Aide. DJ. The Pity of call Cl, he Cambridge, Nicho JG Mari, AR. ac, PA and Wallac, B
Engl Cambridge Univers Pres 18 on Nin Bin, cd. Sander, MAS Sir.
Cowan M Silo Can Scene CE Spa Rae 20
‘ore. MD: fl Hopkin Unnendy Pre, 201
Kandel, ER. Seward Jewel, TM Pini of
Neo Sen he New Yorks Metra 200

Acion Pott Animation Tutora onthe Acton Potential
‘ata ra pe 4003 igueva phim Moon psy queens ct-smensitrainsoctpot hin
This ste provides coll animation of the nic en ol an animation the acto pea sth

76. BEI carter 2: cor and inet Cah fe ena pe

Acton Potent Simulator
‘phe medvayneedujtram are nm
an hte ich a TH and Eom

Synapse Web
Rapa ed

Thi ate dots un ann of pcs and includes
images of nape conceal
ego apes

rr ablongman concen

Cal Membrane Animations
ere 21 couter Mm

"Tio ie ponies seis of animation rl the e
‘membrane porel The animation request

77. Structure of the
Nervous System

78. PR
The Left Is Gone

OLO!

as Ssang woman with confused Tre ein gret er “No, yours. Look tsa part of
histor of high bloc pres which sed eed how she wes feng. Fl vou" he rad with is fingers om,
‘nas ot esponding welt the mesa: guts she said do nom why eam ter aldo

one wa thing One eennge Piper” “il oups she si sti
‘was ating in her rciing chai reading” "Canyousee the other peoplein_scundingunconinee,
the newspaper when the one rang.” the com” When we returned the eset
She goto of her car nd walked to Why. sue” tounge, the ce of eulogy sd at
the pone. As ed, she began feting “How many ar there?“ we had seen si example of uni
‘iy aná topped to ha ent the Shetumedher ead the ight eral neglect coed by damage to par
Koren table She has no memy 8 and began courting She stopp when‘ pro the bain “Fe sen many
what happened ater that She had counted the people atthe fot ases ne this” he pane. “People
ne next morning anios who of he bed “Seven” she reported. ant ere sensations rom the et
al oped by to have ole wth "Uat about? stad ave rom de of he 00) bu they Ju on pay
Mss. foundering on te foto her bed “What? she id, ation to them A wean wl ut

‘mumbingncoerety The righbor looking st he people he hd aready | makaup on othe ight de of er
{led an ambulance, which ook MS. counted "Hao you lo No toward foe, anda man wil ano ony a ol

toahoptal Your et" the ve repeated Slow, Meur When they pto a sit or a
Two dy altere admision vs the eat ebepan turing cot they ile tooo
inate inbertoom, slong witha gow herheedtothelch The voca over the ight om and rou bt
of people being led by the che of neu: sting. and finaly, she sam who wes en they forget about thee
fologe The netlogtaressentin taking “ON ane a “ques tre armandlt the garment ang fom ane
‘urge o eras ud ae tous aremore of you Souler They ao on ik a things
that one ha hd stoke nthe back Te resident approached the Tecate toward he tor even he et
par of te int del th brain Me leido! herbed and touched aves of tings Once sara man ho
Aadattachedactscntoanilum- _ heriefkarm “What the dust shed eating bras. He
rated viewer mounted onthe walland asked. “Where? shed “Hee” wasting ns bed with auay in ont
Pad home usa white spot caused by he answered ola up her am. ‘thin There wat at of pancake on
{he accumulation of blood ina partic and moving itgentyin font of herp. Ave you al doe? asd.
Ioregionfherbran.(oucanlokat foe See he si. turns he pt round
the xanyoure you er isshown “OR thats an am~ 0 at the unete par wasn hight.
Infgue 517) “ana? Whose am?“ ie ue arte ook ands, Were
‘About dose of us entered Más inne. loves must be the hel that come Ham

saone a mae but seemed your”

Oca
es to
Soper ae

a

roscar nc how the brain works. To un

with the basic

be aca

“ructure ofthe nervous system, The number of terms induced in this chap
teriskepttoa minimum (butasyou wll se, the minimum ssl a rer large num-
ler) (See Chapter 3 Animations: Figures and Diagram) With the framework yo will
receive from this chapter and from the animations, you should have no trouble
Icarning he material pres pte

to discuss the terms
rain vas described long ago,
without the ad ofa microscope was given a name
Early anatomis named mon rain structures according to ther Similar to com

79. ace object: angle or “lmondiahaped object's hippocampus, or en | nur Anim ee ano
en, or “knees coto or “ark pons, or “ge or “hook” an | Sram cena o hee
ea few examples Throughout this book il translate the names of anatomical | ee ora rene soem
{able For example, knowing that srt means "bak (Ike the bark ofa we) wil | 00er
Help yu to remember thatthe corte isthe outer layer ofthe

‘When desrbing features ofa structure as complex as the brain we need o
scribed relative to the merida an imagkary Ine draen drug theo reer ee

co the fron of the rain. For imp take, les consider an animal wach | ane ae

as Figure $. shows an allgator and two humans. This aligaor | "ray sy ge

Certainly laid ou ina linear fashion; we can draw a straight Hine that stars be- | Tae Tons one
An its yes and continues down the center of ls spinal cord. (See Figure 3.1) | tex naar rg peros
The from end anterior andthe als pomor. The terms rostral tard the | an One Pe nl velo

Sis and frontal ews aligaor and human, soning he ems uses o denote atomica érection.

Rosa cava or
Pr ose a — — a
paa Vers

gai À 4e ass

6%

Cassior par
ES

80. ‘Senso gr
‘emma scion pepe
seta “ond th
fem ma econ perds
Wrote

aay tre mc
medal Tons me oe
‘i ay tom es
pater Lct ese
Socata

coma La on te
‘ponte sor of bay
a in ace
ont action Ac e
though De a pio
‘git aci sd sce
‘fe bon prio
reac on rentar te
rap pane The ae
Teoh nwo perpen
tothe na aces an

Se of the Rens Sem sv ablongmancomieatonte

Peak) and caudal (toward the til) are ako employed, especially when referring
specifically o the brain. The op ofthe head and the back are part ofthe dorsal sur
face, while the ventral (font) surface faces the ground. (Dos means "ach, and
trum means bell") These directions are somewhat more complicated in th
human because we stand upright, our neuraxis bers, othe topof the head pr
pendiclar o the back. (You il ako encounter the terms super and infer In ne

nto the brain, prior means abone, and nr means “lon.” For example
‘superior lic ae located above the infor ola) The frontal views of bot
algatr and dhe human state the term lateral and medial toward the side
and toward the midline, respective. (See Figure 3.1)

‘Two other seal terms are fuiraland cnialatral.Ipalateral vers 0 struc-
tres onthe same side of the body. Fe say tha the olfactory ul sends axons

ipsilueallnemisphere, we mean that he lett olfactory ball sendsaxonsto the elt
hemisphere and the right olfactory bulls sends axons to the right hemisphere. Cow
tralateral refers to sructures on opposite side of the boy. we say tha a partic
lar region of the let cerebral cortex controls movements ofthe contralateral hand,
ve mean thatthe region control movements ofthe right hand.

"To sce what iin the nervous stem, we have o cut it apen; to Be abe to con-
vey information about what we find, we ice ina standard vas. Figure 52 shows à
Human nervous ss

Wecan lic he nervous qe

three way

1.Transersch ike a salam, giving us eros sections (also known as Frontal sec
tions when referring wo the brain)

2 Parallel tothe ground, ing us horizontal sections

3 Perpendicular o he ground and parallel vo the neurai, giving us sagital ec-
tions. The mideagital plan cides the brain into tuo symmetrical has, The
sagital section in Figure 32 lies nthe midsagital plane.

Note that because
othe ground

our upright postu
(Ses Figure 3.2)

e, cross sections of the spinal cord ae par-

An Overview

The nervous stem consists ofthe brain and spinal cord,
eros sem (CNS), and the ra

hich makeup the ental
serve, spinal nerves, and peripheral gang,
ich constitute the periphere! nos stom (PAS) The CNS is cneaed in bone: The
brains covered by the shal andthe spinal coi encased by the vercbral column.
(See Table 3.1)

Figure 83 shows the relation of d
body. Do not be cor

brain and spinal cord to the res of the
crm infamia label on this figures these sruetutes
il be described later (See Figure 3.3 om page 06) The brain a large mascot net
‘ons, ls, and other supporting cell Is the most protected organ ofthe body, cn.
‘ase a tough, bony sll and oa cerebrospinal uid, The brain
‘receives a copious supply of blood a ically guarded by the blood-brain

Table 3.1

Central Nervous System (HS) Peripheral Nervous Sytem PS

81. En Da
Pues eton ty pean human ana
SS

má DA

Sage
pane

Meninges

€ entre ania and pe
anglais covered by tough connective tissue. The protective sheaths
ind spinal cord. are referred toaethe meninges (singular: meno.
hc meninges consist of three layers which are shown in Figure 33, The outer aver
is thick, tough, and Nexible but unsiethable; its name, dura mater, means “hard
mother” The middle layer ofthe meninges the arachnoid membrane, get its name
fromthe weblike appearance ofthe chi tera that protrudo from (rom
the Greek am meaning Spider aru
ane, sft and spony, lies Beneath the dura mater Closely attached tothe brain
and spinal Cord, and following every surface consolation, ithe pia mater ("pious
mother”) The smaller surface blood vesels of the brain and spial cord are con
tained within this layer. Between the pin mater and he arachnoid membrane a gap
called the subarachnoid space. This space filed wth liquid called cerebrospinal
id (CSF). (See Figure 33)
The periph
‘The mide
the brain and spinal cord. Outside the
layer (dura mater rater) f
‘cranial nerves and the peripheral ganglia

5) is coered with wo layers of meninges.
CSF covers onl
ner

marines ng marine
ren Tee opt
(enges u an ne
retold membrane roy
The mae Dr he menes
pia mater Tet he
Eve ban thn ana ion
Suberchni space Te
cet CS Ac
ame ne won orale

82. BEA charter 2: cu eros Spm ‘rerablongmancomiatonse

Figure 3.3
Ue ten oth neon ote theo th dy. De De msgs a ove

ru tem À ar ve fhe ower spina er and a eu,

ener Ans marte
Saturno space es
a hod

game

a Across abece

Pater

Suracs lr

age oa
ret pon)

0 O

The Ventricular System and Production
of Cerebrospinal Fluid

clik. The considerable weight ofa hu

83. ‘The vente str of the bain a Lateral ew of he ese of he ain,

handle a fresh brin from rece

deceasc human wüh- | venice wen un On te
wa living human is wel protected, I Moats in | FW ces
tharachnoid space, Because the brain come | tea vente One le mo
eich is reduced to approximately 80 y ties de eme
is considerably diminished. The CSF surround ti

rin and spinal cord ao educes te shock to Uh ental nervous tem that | Beti the e

Fortately the intact bra wi
à bath of CSF contained within the
Pete mensa in iui hs
pent on dhe bas of th
would be ast by sd Bead ove

The brain contains cries of holon, interconnected chambers called venrcos
(inlets) which ar filled wits CSE. (See igure 3.) The La roma
the lateral semis, which reconnected othe ir vetii. Their vence | mie one ee
istocated at he mine ofthe bran: wal ide the surrounding art of | Ban Gate Pere
brain into mmetrical habs. À brie of neural celled the mar mal | Bencina
comes through the mide ofthe thi ventricle and serves convenient refer | fourth vee The ete
“ne point The cerebral aqueduct, lng uhe- connets he third ventilate | ad en heen
fourth venti. The acral vencio conse the ft and second ventric, ut | 28" ol fos eer
they are never flere oa such (See Fire 3.) emcee

(Cerebrospinal a i extracted fromthe blond and resembles blood plasma in| Sa ety
it composiion. Kis manufactured by special ne with an expecially rich load | Site atorado
sippy called th choroid plexus, which potros mo four evene. CSF | Somes?

cl continous the oral ole al CS apronmately 123 andthe
take for hal ofthe CSF present nthe venti

replace by fet Md) about Shours Therefore, several imes
{ced by te che plex ca dy

Cerebronpina ids produced by the choroid plexus ofthe lateral ventes DA
and ows int hide More CSF ls producen his once which then ns
as rang te crol uc code oath senile wall oe cares || tana etr

produced. The CSF leaves the fourth ventricle through small openings that connect om ne menigen the ventral
‘withthe subarachnoid space surrounding the bran, The CSF then flows through the er and pios
Subarachnoid space around the central nervous stem, where i rebord into ean and eabsrpen

the blood supply. (See Animation 3.1, Meninges and CSF) hese

84. BETA noten > scrote Nenu Spe or alongman conitonse

rames internat sure of
etl human rin

INTERIM SUMMARY

Basic Features of the Nervous System
Anatom have adopted à set of ems to desc the Icons of part ofthe body
Antro toward te had, poseo tonara ce ta tra tar he ad, mad
‘tomar he mile, donal tomar he back, and vetas toward he Wont sae
fin y ne special a le ness ster, srta means omar he beak lr
ose, and aud means omar he al. palote! mes “ae ad and conto!
means ote ie À os section o, nr cae ofthe bran,» ol etn cs he
reves stem at ght ange to the nero, horizontal ection ses the Din prall
{o the ground, ond a saga section sit perpendl othe ground para he

“The central neous stem (XS) cons ofthe bain and spins cord, nd the
peripheral neous tem NS) consi ofthe spinal and canal nerves and periph
Seng. The Ni covered th he meninges dre mater, arachnid menta, nd pa
rte The pace unde te raid membrane filed wth cereal o, nui
{heran ans Te PSs covered ony the ra mater and pa mater. Crea
‘ts produced in he cori pln of he tral thr, forth eis, Hows
{tom thet atea ventas to the dr veni oh the cer queda io
the fourth veri, then into the subarchnld space, and nal back In the ood
sso

‘complicated, an understanding ofthe base fea
akes i easier o learn and remember the location of
fhe most important structures. With that end in mind, introduce these features
Mere in the context of development of the central nervous sate, Too animations
will help you learn and remember the struct of the brain. Animation 22, The
Rotaable Brin just what the tle implies drawing ofthe hua bra hal yn
‘an rate in tree dimensions. You can choose whether to se some internal sue
tures oF see specialized regions ofthe cerebral cortex, Animation 3.3, Brain Ss
‘even mote comprehensive. I consis of two set of photographs of human brain
slices, taken inthe wansserse (frontal and horizontal planes As you move the cur
sor across each slice, brain regions are out and thei names appear I yo want

an click om the region, You can also
around by licking and dragging,
Finally ou an ext yourself The computer will present names the regions show

Although the brain sexcco
tres of brain development

Development of the Central Nervous System

The central nervous system begins early in embryonic fife a a hallo tube, and
maintains this as shape even fer ti ul developed, During development, parts
fie tube elongate, pocket and folds form, andthe tose aru the tube thick
fens until the brain reach it final for

‘An Overview of Brain Development

Development ofthe nervous sie begins around the eighteenth day ater com
ception. Par of the adem (outer layer) ofthe ack of the embryo thickens

85. A xtumaticoutne of tan deeapmant, showing relation tothe verte) a Eas
“evelopment (ond) Ltr in evelopment) lateral af the are element
oman ram, showing the brainstem “phased n= The clos a furs eno coripenäng eos.

Fortran Man Had Toenspalen Maceo

We Sac =

= = Arena
e ancien
ont a Tem a
x Eten
/ eda ‘pial cord
<< (o)
x
EN)
Horas. Teran Pas ee
o
forma pa The ges of hs plat form ges ia eut or each al
line rosral-cantal diction. By the ren,
these Figes touch ech ter oye
Deal and pra con
day of deslopmen the cura tb elos, ad sor
tn end Bas decloped te Inerconneced chamber These chambers become
venir and ie sc a somo them becomes he re majo pars ofthe
trai: the forebrain, ih mia, and Ihe Rian (ce Alam and 236)
As development progress, the rosa chamber (de force dite into thee
separa parts which Become the to era venis andthe hid venice Th
erde becomes he eencepeon Cond train) a
sn.
fg
develop In the hina: the mctencephalon Caleta) athe pele
on Carentan" (See Pure 20)
“able Sf anomarzs te tes have rod hee and mentions some of
major rues end each part the ra. The cles
Ahonen Figure 35, Tc truco il he deci in dh emainder
tern the order in which hy ar uc in Tale 32, (Se Table 3.2)
Details of Brain Development PROTA
Brain developm i oc que era a
appreciate 1400 (abou STH) and coming olaa andres of benef | Serien Te een

Ser os on of eet
cells Where do these cells come from, and what controls thee growth ovo oe

86. MIEDO citen : scare 0 ers Sten nr aengman comen

ere nn aura
Per ee
aies

ai gb Sc
‘esi pus on
as
Ps

trade us asf ee
onan ct etree
ent
conri Don
creme
nein

The cell hate the
tothe cells the central nerveuse, These cells dive, produc
la which then migrate aca from the center en weeks alter conception the
ff the human fetus about 1-25 em (05 in.) ong and, in tone secion, foe
teicle—in other words, hollow space. By 20 weeks the brain about 3 em (2 in)

hae the basic shape ofthe mature brain. Incros section we sce move brain
inc than ventricle.

Lets consider the development of the cerebral cortex, about wt
now, Cate means “bath” and the cerebral cortex, approximately 3 m
Surround he cr

cerebrales

Iye—the ventricular 20ne—give vse

moat is
n thick,
bral hemisphere ike the bark ofa tree, Corrected fr boxy size,
tx is larger in humans than in anyother species. Aswe will we ci
the cerebral cortex play a role in cognition and control ol

“The cercra cortex develops from the inside out Thats the first cesto be pro-
duced bythe vemrcula zone migrate a short distance and e
“The next ells passthrough the fs Layer and form the second one. The Hs et
Be produced mus pass tbrowgh al before
"What guides neurons o, resting place? Ral (1972,
‘ered that special form of lial ell provides pathways that neurons
Air migration. These cell radial gi, extended ibers dilly o
a wheel, These fibers en in cuplik feet hat at
cher these bers grow along,

cells in the ventricular zone that give
cells. During the fst phase of develope
Founder cell and increasing the size ofthe
to as symmetial division, because

‘ofeach founder cll produces neo

1

phase founder cel idear

remains in place, and a neuron,

1 cerebral cores, guided bythe fiber of a radial gal

aber ike amochas, pushing their ay through net
dl coming to vest. (See Figure 3.6)

‘ell Neurons cra along ra
ons that were born carr and!

87. The Central Menus Sen MT

co scan tough te nervous stem ean its evap Ray oem la ces
Foto guide he gration of new ered erent.

ap Vom tae Phat pee capt go PS A yp He OOH
Algo e een 1985, 1D 8

The period of asymmetrical vision lasts about three
man cerebral cortex contains about 100 Billion neuro
neurone migrating along radial glial fibers on a give
cates me
ones distance to go because he cortex s thicker by then, Their migration takes
aout io weeks. The founder cell
‘eve chemical signal that cases them vo die—a phenomenon known as apopto-
sis (literally a “alin aay"). Molecules te chemical that conveys th
‘vith receptors that tte killer genes within the ell, (A cells has
baton tothe them on.) Once
rons have migrated o thie final location, they begin forming connection with
‘other neurons. They grow dendrites, which receive the terminal buttons from the ax:
ons of other neurons, and they grow axons oftheir own.

The ventricular zone gives re to more

‘eves a signal from the postsynaptic cel
‘come too late do not find any available space and
‘isaining signal, This scheme might scm wasteful, bt appa
process found that the safest stratgy vasto produce too man Peer
Fight establish synaptic connections rather th sae geet eh
numberof each spe of neuron Seon mee

apoptosis poto On

88. TN ov ablengman comietonse

Evidence of nerogne (0) A an rough a ar of te Nppoampu soning ai conning DNA

lola wth aan uc) maga we paro! me sete
Non cotos eons .
‘ “oi ont a € es

De

@ o

D € Jamal Compas Merc, TO A CORTE
Res pino Wy sy re Ste

During development, thousand of diferent pathnays—groups of axons that
connect one brain region with another—developán the brain, Within many oF exe
pathways the connections are orderly and st fe, the axons of se
ory neurons from the skin form orderly connec ra: axons rom the
Tile finger form synapsesin one region, hose of form syapecs i
‘neighboring region, and soon. In fact the surface of the body is “mapped” on the
Surface ofthe bra, Similar à of the ese i "mapped on
Another region ofthe surface of

many years recarchers have believed that numas (production of
neurons) doesnot take place in the full developed brain, However, recent stud
ave show this belie to be incorrect—the adult brain contains some stem cl
(Similar tte founder cells that give rs 0 the ells ofthe developing brain) that
‘can divide and produce neurons. Detection of nendy produced cells is done by ad
‘ministering a small amount ofa radioactive frm of one ofthe nucleotide base hat
‘ells we to produce the DNA that is needed for neurogenesis. The next day thea
mals brains are removed andl examined with methods described in Chapter 3. Sch
studies have found evidence for neurogenesis in the adult brain (Cameron and
May: 2001.) (See Figure 3.7) However although the mature brain can produce
new neurons, here no evidence yet that indicates that these meurons can establish
connections to replace neural crits that have been dexroyed throug inary
Stroke, or disease (Horner and Gage, 200).

F

The brains of the earliest vetebrates were smaller han those of laer animal;
they were simple as well The cvolionary proces brought about
responsible for he development of more complex br
and more interconnections.
large than that of any other primate when corrected for
mes larger than that of chimpanzee, our clones ela
ange brain? Consider
one of chimpanzees isons
112 percent. the number of genes responsible forthe differences been the chin

89. ppanzee brain and the human brain must be smal. After all, only small percentage

ff the 1.2 percent is devoted to brain development In act, Rake (1988) suggest that

the size differences between these o brains cod be cased by avery simple proces
We sts

sion ofthe fou

se of the ventricular zone increases
der el located there. The

on doubles
of founder cells and thus doubles the size of the brain, The human
nes larger than tha of a esas macaque monkey. Thus, between three
and four additional smmetrca division: of founder cell would account forthe
Terence in he size ofthese two brains Infact, the sage of smmetial division lasts
about two das longer in humans which provides enough time for three move div
sions. The period of asymmetrical division islonger too whieh accounts Fr the fat
‘that the human corte is 15 percent thicker. Th mn ofthe
symmetrical and asymmetsicl periods of development could be responsible forthe
increased ize o A fe simple mutations the genes that control
the timing of brain development could be responsible for these delay,

The Forebrain

As we si the forebrain surround the rostral e
components are the elencephalon and

ofthe neural

he. is vo major

Telencephalon

The elencephalon includes most of the two symmetrical cerebral hemispheres
that make up the cerebrum. The cerebral hemispheres are conered by he cerebral
«cortex and contain the Imbie system and the basal ganglia, The later two ses of
structures are primarily in the subcorticl regions of the rai—dhowe located deep
‘within i beneath the cercbral cortex

Cerebral Cortes. As we sa cortex means “bath.” and the cerebral cortex sur-
rounds the cerebral hemisphereslike the bak oF tee In humans the cerebral cor
tex is greatly convoluted, These convolutions, consisting of sull small grooves).
fissures (large grooves). and gr (bulges between adjacent suc or sure). greatly
enlarge the surface area ofthe cortex, compared witha ooh brain of the same
Sie. fat two-thirds ofthe surface of the cortex hidden in the grooves thus the
presence of gr amd sc wipes the area of the cerebral cortex, The total surface
reais approximately 2360 cm? (2.512), and the thicknes aprosimateh 8 mu

The cerebral cortex consists most of gia and the cell bodies, dendiies ad in
terconnectingaxons of neurons Because cell predominate the cerebral cortex has
grayish brown appearance, and is called grey mater (Sec Figure 3.8) lions of
axons run beneath the cerebral cortex and connect is neurons with those located
‘sewhere inthe bran, The large concentration of myelin around these asomo ges
(his tie an opaque white appcarance—hence the term sie mae

Ditlerent regions ofthe cerebral cortex pero functions. Three re
sions receive information from the sensory organs. The primary visual cortex, which
Feccives visual information, slocatd atthe back of the bra on the inner sr faces
‘of the cerebral hemispheres—primariy on the upper and lower banks ofthe ea
carine fissure, (Calrnemeansspurshaped.” See Figure 3.9) The primary auditory
cortex, which receives auditory information, is located on the upper surface ola
deep sure in the side ofthe brain lateral fissure. (See inset. Figure 3.9) The
primary somatosensory cortex, aver
us reeves 39 shows, diferente:
ions of the primary somatosensory cortex receive information from der)
ions ofthe bod In addition, the base ofthe somatosensory cortex receive in
formation concerning taste. (See Figure 3.3.)

the Coins Sp A

forint ret lo pe
‘etre wessen wu
pre

o vemo
Fe
sort pon Tan
Bean mean Soars
cn a a u u
ER
te
ye nt ps ve
mojada oes
nye ro
ea ar a ae) à
ee
rm ty mn Da
Intra eT oe
somes tome pres
Beeren,
Pen en

91. Wit the exception flacon and gustation (taste),
sensory information fem the body or the environment is

Sen 0 primary sensory cortex ofthe contralateral hen
sphere, Thus, the primary somatosensory cortex ofthe
Tet hemigphere le ing the
{ef primary vial cortex learns whats happening toward

the person's ight, and o on,

The region ofthe cerebral cortex that is most direct
involved inthe control of movement ie primary motor
cortex, located justin font of the primary somatosensory
Cortex. Newrons in different parts ofthe primary motor
Cortex are connected to muscles in diferent parts ofthe
body The connections, like thow ofthe sensor regions
ofthe cerebral cortex, ate contralateral: the left primary

‘motor corte controle right side of the body and sie
versa: Tins a urgcon places an electrode onthe sur
Face of the primary motor cortes and simulates he new
ronsthere witha weak electrical current, the result will be
mosement of particular part of the body, Moving the
electrodo 10 a different spo will causa diferent part of
the body to mone (See Figure 39) 1 keto think of the

ip of primary motor cortex asthe keyboard of a piano,
with each hey controling a diferent movement, (We wl

Jes thordy aho ihe Plot ll pia le) Te aby to aviat depends evi on rats euros in

The regions of primary sensory and motor cortex oc

«cupo only a small part o the cerebral cortex. The reat

on and action: per
ceiving, learning and remembering. planning, and acting, These processes take
place in the association areas of the cerebral cortex. The central salts provides a
important dividing ine between the rostral and caudal regions of the cerebral cor
tex (See Figure 23) The rostral region is involved in menementelaed actives.
such as planning and executing behavior, The caudal region i mein pe
eng and learning
Discussing the various regions ofthe cerebral cortex is car we have names
for them. In ac, the cerebral cortex ive ¿mo four areas or be named for
the bones ofthe ul hat cover them the frontal lobe, parietal lb temporal lobe
and occipital lobe. Ofcourse, the brain contains two of each be, one in each hem
sphere. The frontal lobe (he front) includes everything infront he central ul
«us. The parietal lobe (the “wall” islocated on these af the cerebral hemisphere
jus behind the central sulcus, caudal o the frontal lobe, The temporal lobe (ihe
“temple juts forward from the Das ofthe brain, ventral o the froma and parietal
lobes The occipital lobe (rom the Latin a, in back "and en “heal lie
the very back ofthe brain, caudal tothe parietal and temporal lobes. Figure 3.10
shows these labs in three views of the cerebral hemispheres ventral sew (a view
na midi view (a view ofthe inner sla ol the right hemi

sphere after the left hemisphere has been removed), and lateral view. (See Figure
310)

Each primary semory arca fe cerebral cortex sends information o adjacent
regions, called he semsory association cortex. Circus of ncurons

formation received fom the primary semory cortex
perception takes place there, and mem

les ate stored there, The regions of the

x located lost tthe primary semory aras receive i
Formation from only one sensory system. For example, the region closes tothe pr
des ital information and stores vial memories Regions

(ofthe sensory association cortex located ar (rom the primary sen

92. BET, caen 2: ive! menos Str wore ablongman comiarsonse

‘he oo of cerebral corte, he primary sr and motor cartes, and the scan core a) venta
Wem the bao the bain) Maga ew, eth he cerebellum and han tem fron (atl We

me ct Temporis

(res schen

information from more than 0
xy ae involved in several
memories. These regions make it posible 10

Formation From more than one sensory stem. Forex-
‘ample, we ean lear the connection bewocn the sight of
3 particular face and ıhe sound of a particular voice.
(see Figure 3.10)

I people sustain damage tothe somatos
cation cortex, their defies are related to somatosen
‘ation and to
hey may have difficulty percciving the shapes of objects
at they ca touch but mos see hey may De unable 10
name parts of thei bodies (see the ease below) or they

xd of perceptions an
gra

People who si
ay have

damage othe aitory asocio
icli percching speech oF even

own. People who sain damage to regions of
where the somatosensory, ist

inl reading or writing
he posterior part ofthe brain

Justasregionsot the se
inohed in perceiving and ve

93. tion cortex, s known as the prefrontal cortex. This region ofthe bran is tess

soled with the control of movement and more involved in formulating plans and
Degen

‘though a

vo cerebral hemispheres cooperate with each other they do 1
ons ate latmazrd—located primarily on
hemisphere participates in the ana of
“extraction ofthe elements that make up the whole of an expe
takes the lft hemisphere particularly good at recognicing sia!
and controlling sequences
ofthe ft and right hemispheres are re.
versed The sera functions hat are performed by the left hemisphere include Ve
hal activites, such as talking, understanding the speech of other peopl, reading,
and writing, These abilities are disrupted by damage to the various regions ofthe elt
hhemispher, (Ll say more about language and the bran in Chapter 15)

In contas, the right hemisphere is specialized for sli i is particularly
‘good a pati holated elements together to perceive things ava whole, For exam
ple, our abil o dew sketches (especially of rec dimensional objet) read maps.
and construct complex objects out of smaller elements depends Healy on
‘of neurons that are located in the right hemisphere. Damage to the rig
sphere di

e not amare ofthe fa
cent. Alto
tions, our perceptions and
the corps callosum, a lage
association cortex ofthe let
lobes are connected, the ltt and ight parietal les ar
suse of the corpus allosum, cach region of

that each hemisphere perceives the world differ:
heres perform somewhat diferent fune:

“are unified, This ny accomplished by
of axons that connects corresponding parts of the
and right temporal

h he two cerebral he

spinal cord) has been sliced denn the mile, diving it ito is two sy
alv. The eft hal has heen removed, so we sce the inner surface ofthe ight hall
The cerebral cortex that covers most ol the surface of the cerebral hemispheres (i
ding the frontal parietal, occipital, and
(Chev cortex, becas ts ol relatively recent evo
cerebral cores, the imbie corte, is located around he med
bral hemispheres (mins
som ofthe limbic cortex, can he sce in this figure, (See Figure 3.11),
Ifyou look back at the top to drawings in Figure 8.10, you will see that
‘cortex occupies the regions that have mot een colored in. (Refer to Figure 3.10)
Figure 311 ls shows the corpus allow, To lice the brain nto ls o sy
etica halves, one must ice though the middle of the corpus callan (Reca
that I described the spitbrain opera he corpus cllosum I severed,
in Chapter 1) (See Figure 3.2)
An imations on the CDROM will
nt you dee the locations of the sp
alized regions o the cerebral cortex. (See Animation 3.2, The Rotaable Brain)

Another fon
edge ofthe cere-

Limbic stem. neuroanatomist, Paper (1937) suggested tha a et of iter

con circuit whose primary function vas motivo
and emotion ded several regions ofthe mb cortex (already de
seribed) and a set ofimterconnected structures surrounding the core of the lore:
brain. A physiologist, Mack fe system to include other

the hippocampus (ca horse") and the amy
xt tothe lateral ventricle inthe temporal lobe, Th

Ye located

The esa rc Sven METRE

prota an Da on

corpus caga ah en) à
esr Dem
nice Morey
toe rote cel
Feasts ol ee
ingle os sng ow
Free
Spain De certs
hers at to cop
Imbienptem À go tn
pores
tran ne, emp, nep
Ve polos sd er
hippocampus otras
teat tenga econ
am mig) Ase

See Animation 32, The
ett rin for an

‘ofthe human bs.

94. BET caen 2: secre o enanos ster

‘wo ablongman com/asonée

A méga ofte ain aná tof he spa cons

simplest form ol cerebral cortex, appears to hive co

‘he major components of the im tem. Al of he eft
mps att a ine mi ptr ha been tere

ied withthe developmen
“of emotional responses An you in Chapter 14, we
hose noxe that parts ofthe lmbic system (notably the
hippocampal

that sar

nd some regions of
specifically invole in emo
Sons of emotions, emotional
ion of the signs of emotion

canoes and recog
mother people

Basl Gong.
subcortical
Anterior por
group of ncurons of sa
from the Greek word for "nut can reer to the inner
portion of an atom, tothe structure of a cell that con
{uns the chromosomes, andas in this case a co
Action of ncurons located within the brain) Ti
part of the ban gn he codate nucleus, the
tan, ad he globus pais (he “eles with a.
al globe". (See Figure 3.13). The
Ihe contro of movement,
case le cased by degener.
urons located in dhe midbrain that

95. hein of he ua ganglia andcencephalon,ghostedin 0 asemitramprent ran

the caudate
are of weakness, tremors, igi
ning movements

Diencephalon

The second major division of the forebrain, ie diencephalon, is si
he mesencephalon: i surround

Testo mos important structures ar
ue)

diencephalon. is state near the mil of
y medal and caudal to the basal ganglia, The
two lobes, connected by a bridge of gray mater called the massa intermedia,
pierces the middle ofthe third ventricle, (See Figure 3.13) The masa intermedia
probably not an important str
ple. However, itsertes asa
pe

Mos neural input o the cerebral
much ofthe comica surface can be divided into regions that receive project
From specific partsof the thalamus Projection fibers are set of axons
¿cl bodies located in one region a the brain and smapae on neurons located within
another region (thats, they proto these regions)

The thalamus is divided nto several ce, Some

alamic nuclei recche sen-
these null then relay
the sensory information to speci sensory projection arcas ofthe cerebral cortex,
“example the lateral geniculate nucleus receives information from the eye and
‘andthe medial geniculate micleus receives

er car and sends axons o the pr

¿do mot rely sensory information. For example, the ventrolateral nuceus receives

oer te re a
SEE hear na
polar pan rem
‘mammary bodies mam
Shine palm ota
Same taie noses pol
Beinen

sang À ou wo
amené er
ec nun de gob
ess lua nd Ani
‘se para cotas
econ rt,
ia td ect mado be
ams and parame
thalamus telat ton ot
be derretir ete abe
Seto arm a
engen cere cree
projection er an on a
Peon more reno ore
later gente pues à
(jo oct es waht
Ce enn ny ve a
Imei unica nus à
oo ad aes ma he
esol gencate of fe
Sama ee fr tome
‘tty et rg
went à ns
Fre marta ccs

Sind mens any nto

96. BEIM cores 3: sc

petiso

optica Aye arn) An

ante any nd The

nerosecretory a À

rice pe Play Lay
Shaan and

and projects it 1 the primary motor cortex. And

ral Cortex. To accomplish this task, these nuclei have wide

Hypothalamus. Ass name implies, the Bypothalamas lies at
the bate ofthe brain, under the thalamus. Although the postal
Asa reach small structure, isan important one co
the autonomic nervous ste and the endocrine system and ong
nies behaviors elated vo survival ofthe species scale or
FS fighting feeding, ling, and mating

The hypottalamus à state on both sides ofthe ventral por

he bird ventricle. The hypothalamus ls complex

pituitary al the optic chia,
Te merves (from the eyes) cross ram ane side ofthe brain tothe
bother (See Figure 2.4) The role of the Inpothalamas in the con
trol of the four Fs and other behaviors such asdrinkingandseep-
ing) willbe considered in several chapters later inthis hook.

Much of the endocrine stem ico
tulle by hormones produced by cllsin
the Inposhalams. À special stem of
blood vessels directly connects the
fikpredetion manana posbalamas with the anterior pituitary

mother Ont ahormene Blan, (Sec Figure 3.15) The pasha
CCE RE Ban P

noi wen he eurons called eurosecretory cel, lo
E ta on opt, ‘ited mear tc base ofthe pititary sal

secreted by specialized

97. ‘Te Cet Neos Stem

Te lay land. Hormone ess by the neuroetry in he ota en
planes and are comedo the anterior play land where hey cota ot e
Fermones The hormones ofthe pester pita land are produce inthe
pola and core there ves y mens of rpm warp

Negras at
“rst

Fo pata ua gard Foranerer tary gan

4

Prat ak
Aero pro y Posters pay gra

“These hormones simulate the anterior pituitary gland
‘example, gonadatpinsrasing hormone cases the anterior pt
a role in repredactive photogr

bythe anterior pituitary land control other cn.

14% Because fs Function, anterior pitty gland has ben call

the bods “master gland.” For example, the gonadotropi ho

somal (onariesand testes) to release

lic el throughout the body ‘anterior pe
ormones—prolactin and somatotopic ho rmone)—do

ot control other glande messenger. The behavioral effects of

1 contractions a the ime of hr, and vasopresi, ml
hey are produced by wo diferent ses of neurons in | pester pity sland Tie
‘ond an ence Gand at

he terminal buttons in the posterior piuary | Ya amer

within heirterminal buttons | oct ten be
‘yen

98. DER carrer 2 ce of ne neos Sen wor ablongman conieatonse

mien merce | The Midbrain
TEL | re midbrain (ato called the mesencephalon) surrounds the cerebral aqueduct
Imesncehalon imzzensete | and consists of wo major parts the tet and the tegen

‘Son dia spon!

‘ean auras eee Tectum

The tectum (roof) is located in the dorsal portion ofthe mese
incipal structures ae the superior oliul and the

‘The cerebeum aa brainstem. tate
Ver rom te baka te ban Adora view ote

je ofa semivarsparet brain, showing the cretion and brain
ster Meet hemaphere of

Potage

enor HCY Dora Covet

“

99. ‘hata tem, Figure 3.16 shows several views of the brainstem: lateral and posterior
sew of the brain tem inside asemitransparent rain an enlarged view ofthe be

‘em with part ofthe cerebellum cut away to reveal he inside ofthe fourth vent
le, and eros section theongh the midbrain. (See Figure 3.16) The inferior col
¿ul ate a part ofthe auditory stem. The superior collicul are part ofthe vital
system. In mammal they are primaril io in sal reflexes and reactions

mowing sti

tegmentum (’covering”) consis ofthe portion ofthe mesenc
ath the tectum includes the rostral end ofthe reticular formation, several
(lei controlling eye movement, the periaqueductal gray mater,
‘the substantia nigra and the ventral tegmental area. (See Figure 3.164)
"The reticular formation i large structure coming of many mucei (oer
int nal) Misal characterized by a fe, interconnected network of ners
With complex dendrite and sonal process, deed trun mans he net"
arly anatomists were stuck bythe netike appearance of the reticular formation,
The reticular formation occupies the care ofthe brain sem, fromthe lower border
ofthe medulla vo the upper border of the midbrain. (See igure 3,164.) The retin
ar formation receives sensory information by means of yao pacas and pro-
ces asomo the cerebral cortex, thalanis, and spinal cord. l plas role in sleep
and arousal attention, muscle tons movement, and various vital eflxes
tine willbe described more fll in ater chapters.
“The periaqueductal gray matter io calle because it consis most of cll bd
es neurons gray matter” as contrae with the “white matter” of axon Dudes)
y surround the cerebral aqueduct as tel from the third the fourth ven
tcl. The periaqueductal gray matter contain neural circus that control se
“quences of mosements that constittespeciewtypical behaviors such sighting:
mating Aswe will se in Chapter 7. pates such as morphine de-
‘crease an onganisn’'ssensitty vo pain y simulating receptors
ton located in this region
"The red nucleus and substantia nigra (“black substance" are
components ofthe motor stem, À bundle of axons
ered nucleus constats one ofthe two major
Fiber stems that bring moto information from the cerebral cor.
tex and cerehllum to the spinal cord. The substantia nigra com.
tains neurons whose axons project tothe caudate nucleus and
pam, parts ofthe basal ganglia. As we wll se in Chapter 4
egeneration ofthese neurons causes Parkinson's disease

The Hindbrain

“The hindbrain, which surrounds the
‘wo major dhsons the meten

rth venti, consis of
on ande myelencephalon,

Metencephalon
tencephalon consists fe por and the ce

Cerebellum. The cerebellam Cle brain) with is co

osa miniature version ofthe cerebrum e
Gsconered by the cerebellar cortex nd has set of deep cerebel-
lar mac, These nuclei receive projections from the cercbel
cortex and themscles send preci

The Central Menus Sen ME

spt hy)
Infor cli tons na |
Pan stem The “sea he

‘ln reg he ceo
so vrs gt
Teradata to sesion

Beigua gay mate Te
Oro he moan son,
nao coran

deu Alerce ote
santa ir y ar

The cerbetum ys an import ein
out ofthe cerebellum to Costas bed movement

100. DER cuarto: sio teens Sten nn ablongmancon/atonte

‘fee sor descr he
‘ton a mat
ara ball on) À

ep carota ml
(erde pence pe in
‘raphe othe oa os.

‘rowing te atom of De seta

her pars ofthe brain, Each hemisphere ofthe cerebelum is attached tothe dor.
Sit surface ofthe pons by bundles of axons the superior, middle, an inferior cere
llar peduneles ("ite fee”. (See Figure 3.16)
Damage tothe cerebellum impairs standing, walking, or performance of coor
dlinated movements (A virtuoso pianist oF ther performing musician owes mn
vo his or her cerebellum.) The cevebellum receives visual, auditory, vestibular, an
somatosensory information and ¡aho receives information about individual muscle
onement being directe by he brain, The cerebellam integrates this information
and modifies the motor out, exerting a coordinating and smoothing effect on
the monements, Cerebellar damage ress in jerks; poorly coordinated, exiggerated
meemente extensive cerebellar damage makes it impossible even o stand

Pons. The pons large bulge in the brain tem, les between the mesen-
ccphalon and med m. Pans
ans “bridge, but 143.160)
The pon contains,

rule that appear to be important in deep and arousal. I lo conta

does nat relly look ike one, (Refer to Figures 2.17
nits core, a porto

on, including some
a large mr

Myelencephalon

The myclencephalon contains one major truc
“oblong marrow”). usally just called the medula, ren
“il portion ofthe brain te its ower border i th

‘nd of the spinal cord. (Refer to Figures 3.11 and 3.160) The

lui nt

onacular tem, respiration, and skeletal muscle dons,

The Spinal Cord

he spinal cord i a long, conical structure, approximately as
thick a an aul lle Finger. The principal function of

spinal cod isto distribute motor fibers o the effector organs
‘ofthe body (ands and muscles) and to collect somatosensory

= exe control circuit some of which are described in Chap-

1er) ate located here
he spinal cords protected by the vertebral col
whichis composed of tent tal vertebrae
“eral (neck, thoracic (ches), and lumbar lower back) regions
fd the fused vertebra making up the sarl and égal por.
Depas ‘ions of the column (located inthe pele region). The spinal
‘ond passes through a hole in each of the vertebrae (he spinal
foramen) igor 17 strates the divisions and structures of
spinal cord and vertebral column. (Sc Figure 3.17) Note
that the spinal cord is only about avoirs as tong asthe ver
{ebral columns thereat ofthe space filled by mass of spinal
Vere roots composing the eauda equina horses ta). (Refers Fig
we 33e)
Early in embryologcal developme
and spinal cord are the same length, As development pro
rene, the vertebral column gro aster than the spinal cor

the vertebral column

101. “This tferenta growth rate causes the spinal roots tobe
‘most caudal roots travel the farthest before they emerged

is sometimes used in pee surgery or childbirth, local
into the CSF contained within the sc of dura mater suro
The drug blocks conduciion inthe axons ofthe cada equina
Figure 3.18(a) shows a portion of the spinal cord, with the layers of the

Y bundles of fibers emerge from each side of the

„along it donolateral and ventrolateral surfaces,
1 the histo paired sets of

tral roots join together a they
spinal nerves, (See Figure

spinal

yt unmyelinated on)
ated in blue descende

ing tacts are indicated in red (See Figure 3.189)

‘The spn or (0) porn ofthe spl ora showing the ayers of he meninges ane
‘eatin afte spina cord othe veel cou, 9) Aros cion though te sal cr
‘ending ac are shown ne; een acs te shown ne

or

The Centra ecos Stem ACES

domi,
AS
do
‘eon yl
solas Te connus
Beate
erst Ate te
mado cacon da
aud ain op) À
Soe ana ans
sub e eta
e lo nt
ra tonal
Sopra had sand de
‘Sno ee

102. MT carrer: src ote nes Sten sv ablongman cometan

spinal nave perra en

INTERIM SUMMARY.

‘The Central Nervous System

‘The brain consis of thee major visos, organized around the tree chambers ofthe tbe
that develops early in embryonic He the forebrain, the midbrain, andthe hindbrain, The
development ofthe neural tbe into the mature central nervous system lutte in Fig.
re 36, an Tobe 3.2 tines the mjor ions and suis of he bai.

During the fst phase of brain development ymmatrial dion ofthe founder cls
ot the ventricle zone, which ines the neural tube reses ie During the second
phase, asymmetrical division ofthese ls gies ise to neurons, which migrate up the bes
radial ga cesto thee final esting places. Thee, neurons develop dendíts and axons
and establish synaptic connections with other neurons Later, neurons that alt develop a
suffi number of synaptic connections ae kled trough apoptst, The large re of he
human brain, relative to the rains of the primates, appears to be accomplished primary
bo lengthening the fst and second pri rain development

The forebrain, which surrounds the lteral and ti vents, const 8 the tle
cephalon and dencephaln. The telercephalon contains he cerebral orto, the Imbiss
tem andthe baal ganglia, The cerebral cores ls organized into the frontal, parietal
temporal and opt! lobes. The central ulus vides the frontal lobe, which deals speci
‘aly wth movement and the planing of movement, rom theater the lobes, which dal
ima with perceiving and lemming. The Imbie system, which nudes the mic core,
the ippocampus and the amygdala, involved in emotion motivation, and earning. The
‘basa gang patate in the contol of movement The diencephalon consists ofthe tha
mus, which directs information 10 and fom the cerebral cortex. andthe hypothalamın,
‘hich control the endocrine sytem and modulates species ypicl Behaviors.

"he midbrain, which surrounds the cerebral oqueduct, consists ofthe tectum and
‘tegmentum. The tectum involved in auction and the onto of wal flexes and esc
tons to moving simul. The tegmentum contains heretic formation, which important
in sleep arousal, and movement the periaqueductal ray mate. which controls various
‘species tpia behavior and the red nueus and the substantia nigra, bath of which are
parts the motor system. The hinbran which surrounds the fourth venti, contains the
‘Cerebellum, the pos, and the medulla The cerebellum plays an important role in integra
Ing and <oordnating movement The pons contains some nude! tha are important np
and roa The medulla oblongata, to, img in ep and aoura but to plays à
role in control of movement and in contro of vital function sucha har te, breathing,
and blood pressure

‘The ote ar ofthe spinal cord comin of white mater: tons conveying information
up or down. The central gray matter contains cel bodes.

unica with the rest of the body ia the cranial
rss. These nerves are part of the peripheral nervous stem,

hi comes sensory information to the central nervous stem and conveys mes

tothe body muscles glands

Spinal Nerves

The spinal nerves begin at the juni
cord, The nerves leave the vertebral colun
‘ceptors they inert, bra

1 he dorsal and ventral roots ofthe spinal
wand travel tothe muscles or sensory re
ching repeatedly as they go, Branches of spinal nerves

103. ne one Nenous ster ACTA

co aio ofthe inl or sowing he

aten y afferent and effrnt sons ough

evan Ou mar

‘often follow blood vessel, special hos branches that innersate skeletal muscles.
(Refer Figure 33.)

information into the brain and spinal cord are located outside the CNS.
exception ithe vista stem; dhe ena ofthe eye actual a part ofthe brain.) ay 7
‘These incoming axoms ae referred to a afferent axons because they “beat tard” | Mer mon to mo ees
ec ri that bring somatosensory infor: | Stee costa ena
dorsal root ganglia, rounded welings atthe | Hama
¿oral rot. (See Figure 3.19) These neurons are ofthe unipolar ype (described in
Chapter?) The axonal stalk divides lose to the cell body, sending one limb into the
spinal cord and the other emo | tosesctatecr pea nae
i the dorsal root convey soma ses.
el bodies that give rise o th

ofthe spinal cord, The axons ofthese mulipolar ne

rook which joins a dors roto make spina

nb ont to

Me loc within the ray mater | eet anno An

fons Tene the pial cord ia | Scene oo en ese
or

pl reset

lou Ape ene
PR
Cranial Nerves en coge
cad and neck region.One | rene come me rue
=n inland aa rales ee or sl ra. LES

"Twelve pairs oferanial nerves are attached to the ventral surface ofthe brain, Most
ofthese nervesservesensory and motor functions of
ord

105. {rom he olfactory receptosin are complex structures
containing a considerable amount of neural circuit: ctl they are part of
brain, Semsory mechanisms are described in more dealin Chapters band 7.

The Autonomic Nervous System

peripheral nervous sem tha I have discussed Farah r=
ory information from the sensory organ and that controls movements of
skeletal muscles called the somatie nervous stem. The other branch ol

ih eg ands. (Autonomie means
Seltgenerning.) Smoot (associated with hair oe),
in blood veses in the eyes (controlling pupil ie and accommodation ofthe lens)
‚din the wale and sphineterof the gut gallbladder, and urinary bladder Merely
1 organs that are innervated bythe autonomic nervous system suggest
the function ofthis item: regulation of Vegetaive process” in the bods

The ANS consis of tro ystems the ampli donan
the parspmpathti alison. With few exceptions organs ofthe body are innere by
both of these subdivisions and each has a differen ect, For example the smpar

thetic division speeds he heart rate, wheres the paranpatheti ion slow it

‘Sympathetic Division of the ANS
The sympathetic division is most involved in actities asocated with expen
1 of energy fom reserves that are sored in the body For example, when an or
anis is excited, the sympathetic nervous system increases blood flow to skeletal
muscle, stimulates the secretion
a rein blood sugar eel) and causes ploeretion (erection ol fin mammals
‘hat have and production ol oose bumps" in human)

“The cll bodies of sympathetic motor n located inthe gray matter of
‘the thoracicand lumbar regions ofthe spinal cord (hence the sympathetic nervous
system sal known asthe oral system). The fibers of these neurons ext via
the ventral roms Atr joining he spinal nerves, the bers Branch of ad pas nto
sympathetic ganglia (not to be confused with the dorsal root ganglia). Figure 321
shows the relation ofthese ganglia to the spinal cord, Note that individual symp

I ganglia are connected to the neighboring ganglia above and below, thus for
ing the sympathetic ganglion chai. (Sec Figure 321)

“The axons that eave the spinal cord through the ventral root belong to the pre
‘ganglionic neurons With one exception, all sympathetic preganglionic axons enter
{he ganglia of the wonpathetc chain, but not al of hem form symapaes there. (The
‘exception ithe medulla ofthe adrenal gland, described in Chapter 10.) Some axons
leave and tral to one ofthe other sympathetic ganglia, located among the internal
‘organs. Al sympathetic preganglionic axons form synapses with neurons located in.
‘one of the ganglia. The neurons with which they form synapses are called postgan-
‘onic neurons In turn, the postganglionic neurons send axons to he argetorgan
Such asthe intestines, stomach, kidneys, or sweat glands. (See Figure 321)

Parasympatheti Division of the ANS.

The parasympathetic division of the autonomic nervous system supports acti
tis that are involved with increases inthe bodys supply of stored energy. These ac
tivities include salvation, gastric and intestinal moa, secretion of digestive juices,
and increased blond flow tothe gastrointestinal tem.

Cell bodies tha give rise o preganglionic axonsin the parasympathetic nervous
system are located in wo regions the nucle of some ofthe cranial nerves (especially
the vagas nerve) and the intermediate horn of the gray matter inthe sacral region

sonate nervous system The
paral paro nas
ects mas or van
‘sree en
tet perros aon
(ang) a satan te pro
Dead gene tor
reset aan Na
Pen tener
most gang Noes
eur ne mater
reset msn in
Pa pan o
gg een ne
a en se bay $
See eme amet
engin ers
‘tte ses et th
ae oer
uaympnnen avan ne

107. as 33
Samat Nervous System Autonome Nervous System ANS)

pathetic ganglia are located

ofthe spinal cord. Ths, been re
Terved to as the amiante. Pars he im
‘mediate vicinity of the target organs: the postganglionic fiers are therefore
relaie short. The terminal buttons of both preganglionic and posganglionic new:
‘ons inthe paraympathetic nervous system serete acento

Table 33 summarizes the major divisions ofthe peripheral nervous system,

1 parasympathetic division ofthe ANS!

INTERIM SUMMARY

The Peripheral Nervous System
‘The spinal nerves and the cranial nerves convey seso an into the central neous sy
tem and motor axons out rm Spnal nerves re formed by the junctions of the dorsal
roots which contain incoming (afferent) axo0s, and the ventral rots, which contain out
‘ging efferent axons. The autonomic nervous system consists of two ions: the symp
thetic sion, which controls ative that ocur during excitement or exertion such as
increased her at; and the parasympathetic sen, which controls actes hat ocur
‘uring elaation such a deceated ear rate and increased acy o the digestive stem.
“Te pathways of he autonomic nervous system contain preganglionic axons, rom the bain
or spinal cord to the sympathetic or parasympathetic ganglia, and postganglionic axons,

from the gang tothe target organ

Unilateral Neglect

en se people ke Mis, the
‘woman wth unitera neglect we es
Ine that perception and attention re

sameshat independent The prepa
mechanisms of ut rin prove heim
Format, andthe mechanisms motes
inattention determine whether we Be
come ano information.

Uniatranepetocus when he
‘ght parietal lobe damage. The
parietal lobe contin the primary 0-
Imatosesory cortex reales informa
{on rom he skin the mutes, he
Joins the interna organ an the prt
ofthe inner ear ht concerned with
Balance. Tus, ts concened with ne

body and is postion. But that not
athe nt cortex of the par:
alle aio receives audio ond vi
ua information from the association
Cortex ofthe op and tempora
lobes. ts mos important function
Sem tobe to put together informa:
ton abou the movement and action

108. BIE ciar: sucios te heu rem ovmablongmanconietonte

‘ofthe parts of he body withthe lca: that hey mere unsre of the fthand sugges that unilateral neglect extends
ons f objects in space around The simul ent à persons own vl image
tight a e parietal obes each har you ink about the try att mettra two patents,
‘lesomevhat diferent tasks the ft ef of neurology told about the man vi unta neglect to dsb the
«once sl with the potion ofthe who ate ony theight half a pan. Plaza del Duome, a wel Anown nd
pars of the body, andthe ight con ae, ouai at prope with mari lan the yin whch thoy
rns e with the tee dimensional una ree must beable to per. andthe patents ved. Tey athe the
Space around the body andthe on” ene more than the ight val ld. patents fo imagine tat hey ware
{ents ofthat space (he eft portal Remember tat people winter ang athe north endo he pizza
{abe ho involved in language abil. gia fito notice ot only things to and tel them what they sa The pa
ties but they Al be dase te n he et but ao the efthabesot Nets duly ramas the Bulg, but
Chapter D) ‘things But toting between he ony those on the wet, other rg
"atera neglect simply consisted lft and right halves ofan bec you Trent estat ated the pa-

‘of nds nthe et id ofthe visual fisthave to perce the entre bjct— lets 1 imagine hemsehe the
el and anesthesia ote lid of tenue hom wouldyou know where southend ofthe pizza. Th ti, they

the body it aout be nes ati. theme was? named the bugs on he east,
teresing Mahal with pure nist. People wth ultra naglctaho tothe ight Ob, they knew
ea net are nether half Bindnot demonivate ter unawareness ofthe about alo! the balding andthe Ia
alum Under the proper crc fe ha of inge when they craw pc. ton Du they ind the oly
Stanestheyanseehingslocated to tures. Fo example, when keto raw’ han the ug wer located the

thailand they an then some acc, y almost ava secentuly igh ie of he (mann) vial
fone touch the ane ofthe bodies, draw a Gc: then when they find

But noma, they one sch stim the Pubs, they such tem alin, “ou ight wonder wheter damage
and at si the fido of the wold on he Vid Sometimes hey simply tte ft parietal ibe cause unite
and af ir boss not ent Stop fer reaching 6or7 andaome. night neglect. The amer yen bu tt
Volpe. LeDoux and Gazznig (1979) times they write the est of te numbers very sight tina to detect and
presented pir of vil simul peo: undemeath the da. When mue secre tote temporary Fora practi!
ple withuniateanegecone simu aw aay they begin with astem purpose then there no righ neglect.
[sin the left vil fell nd one stimu anda lea or two and than draw all the uty not? The answer tei a mye
lus the ight arial, the people” petastothe ight When eto dow te Tobe su people have geste
reported seeing ony herighthond sgt, they daw wheel and then” some posse explanation bu they are
stimulus But when the imestatos putin spokes but oly on the right” sll gute spective. Nout we
sted the people toy wether nt halves ofthe wheels now alot more about he rin mechs
‘he two sal were dental they an Blac andtuzat (1978) demon. nimsofatenien we wi beable tun.

seed corrector ough Uy al stated asimilar phenomenon, which detand ths dncpany
a ee EEE SESS SE

BASIC FEATURES OF THE NERVOUS SYSTEM 4. The forebra ung the tteral and iden
‘rain and cles consistsofthetlencephalon (cerebral cotes,
mbie system. and basal ganglia) and diencephalon

(alanis and hypothalame.
5. The midbrain, which surrounds the cerebral aque

1, consis o the tect and egies

6. The hindbrain, which surrounds he fou
contain the eereheilum, the pons, and

The central nervous tem consists of 1
spinal cod ii concred with the meninges and oats
in cerebrospinal nid

‘THE CENTRAL NERVOUS SYSTEM

hvemticte
ye medula

2. The nervous stem develops Bs as tube, whic
hickens and forms pockets and fos cells are pro:

duced. The tube becomes the ventricular ste us re
3. The primary cause of the difference between the | THE PERIPHERAL NERVOUS SYSTE?
Human brain and that of other pr 7 and cranial nerves connect the à
nel posal of quale and ap nervous system with the rest ofthe body. The ato

momie nervous stem consis of two divisions, sy

<ivision of founder cell located in
ze. atleti and parasympatheti

109. mo io AE

Diamond. MC, Scheie, A. Band Eh, LM. Th Human
Th ling Bad Neve Yr: Barnes & Noble, MRS.

“Gui N and Willan TH. The Hama I: A
plc Ct, Nee Yor: Harper & Ro, 160.

Heimer Le human Brin an pina Cn: Punta N
‘nao an Die Cuida 2nd Now ik: Springer
Nera, 18

Na WI, and eg Manta Naor

Netter FH. The CHEN Collin of Mab Mains. Vi
‘even Spe, Part 1: naty aná Pas, Sa, NE
‘CARA Pharmaceutical Produc Co. HE

Wooley. TA: Hana. and Gado MH, hein A
À Cu tb Haman Cora aos Sem 2d ob.
Ken NJ Wiley So 208,

Neuroscience Images
UR Peg eaupePTA Simagesimage html
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110. Psychopharmacology ”""””

SA

oy

Neurotranemitters and
Neuromodultors

Ay

1. Describe the routes of administration of drugs and thelr subsequent distribution
‘within the body,

2. Dee rg fechene, he feof repeated admin of rugs, and
the placebo effec.

Describe the eects of drugs on synaptic activity

Review the general role of neurotransmiters and neuromodulators, and deci

the acetyeholineric pathway inthe brain and the drugs that affect these

5. Describe the monoaminersic pathways in the brain and the drugs that affect these

6. Review the role of neurons that release amino acid neurotransmitters and describe
drugs that affect these neurons

7. Desribe the effects of peptides lipids, nucleosides, and soluble gases released by

111. A Contaminated Drug

In y 1982 some people in northern a mba opiate related to meperidine 1 researcher Wiliam Langston the
Gita began showing up at eur [Dame ec the symptoms mini epidemie ppeorsto have artes
om ins displaying dramatic severe ‘looked ke those Fort aie, “wen ayoung man nikon Vly

mtrs Langston Gard Tetrd. patents were gen OPA, the wat sloppy in hl yma ol mat
ani, 1969, Te mostseverelyat- drags to eat hs eae and they erin, Tat dappne do he pe
fected patients were amon totaly por allowed giant improvement in” ence of MPTE whch byan escri
Syed hay wer unable to speak ation ut evenvwith the.” LOMA tnc othe ven

Inti they role consta and ratmen he symptams were debat. sam neurons tat re stn Pri
thew ees were open with a far. ing. normal cares Primo son die" (Levan 1389 467), Be.

Others severa fected, walked ease, DOPA therapy Woks for atime, Case the research hat flowed up
‘with dont tig gat and moved buts the degeneration of dopamine” on that “ko fat,” patents th
Stony and ith gres fic The secreting neurons cortes the D Pain ene ae now ND
Symptons looked ke those of Fuki. lo tseffeivenes Mispaternotre- a dnughat appears to sow the rate
Sons eae but hat disorder hos Spore abo appart ve occured in of degeneration of ter dopamine:
‘ery ord onset nad, rarely the oung pars Langston and al sang neurons. Tere hope tat
ske people befor te middle age lard 190) eu drs may even al the depen
nie paint vere alin the twen- Some detecte work eves tht ton ging patients many more eas
is or ss tires, ‘the chemi hat caused the url! o sta, productive Ine and preven

"ne common actor inking thes o- al symptoms wos nat he the oping the rom eve developing he

entswermrveneus ug naliol te Re Du another chem with aes,

em Pod bee aking a “new erin” whkh as contaminate, Ac

suture, Now is time to il on this information by intro
M of psichopharmacology. Pschopharmacology isthe sy of
eects of drugs on the nero
1 Greek word for “ru

Aswewilseein thischapter drugs have tan its of cin. Drug effects are
the changes we can observe in an animals phyilogical processes and behavior
For example, the effects of morphine, heroin, and other opiates include decreased
semi to pain, slowing of the digesive system, sedation, muscular relaxation,
Constiction ofthe pupil and euphoria, The sites of action od points
at which molecules of drugs interact with molecules located on or in cells othe
bods, thus acting some biochemical processes of these cell For example he sites
‘of action ofthe opates are specialized receptors state! in the membrane of eer
tain neurons. When molecules of opiates attach to and acicate these receptor, the
“drugs alerte activity ofthese neurons and produce thir effects. This chapter con
Siders both the effect of drugs and thei sites of action.

Pachopharmacology isan important eld of neuroxcienc, I has been respon
sible forthe development of pschotherapeuti drugs, which are und to teat ps
‘chological and behavioral disorders. I has also provided tools that have enabled
‘other investigator to sty the functions of cell ofthe nervous sem andthe Be
hasiors controlled by particular neural crus

This chapter begins with a description of dhe base principles of pychopharmacology
‘theroutes administration ofdrugs and thei ate the body. The second section die
uses the sites of drug actions. The final section discusses specific newotransmiter

hhapte introduced yo tothe cells of the nervous stem, and Chapter 3 de
scribed is sie

jesstem and (of couse) on behavior: (Pharmakon

pyehophamacalogy the)
augen roa ng
se of acon The atone
{etl he bo a et

112. BRET caren 4: yrprrnccony ‘wor alongman converse

pharma Te pcs
Span gre atte
outa ne dy tb
toed od ent
Inavenous (mieten i
Barnes
intrpartonst nection in
lap ne naar te
intra (MD join
barros 50 min »
or administration rt

and neuromodulators and the physiological and behavioral effects of specific drugs
nera with them

Pharmacokinetics

To be effective. a drug must read ofthe drug
mus enter the body and then enter the bloodstream so that they ean be carried to
the organ (or organs) ey must eave the Mousse and

isis of action, To do so, mola

‘rage we ate interested in, this me des ofthe d
central nervous stem, Some behaviorally activ drugs exert ihr efecto
ripheral nervous system, but these drugs ar ls important to us thaw those that a
feet cells ofthe CNS
Molecules of rus several barriers 10 ener the body and find thei
vay to ne molecules pass ind
‘quickly: others do so very slowly. And 0
Begin o be metabolized broken down by ensymes—ar exer
molecules either disappear or are transformed into inactive
fragments, The process by which drugs are absorbe, disribucd within the body,
tabolized, and exereted à referred to as pharmacokinetics (movements of

Routes of Adminstration
Fs les consider the routes by which drugs can be administered. or labora:
cis injection. The
Tigui in dhe form of Fine particles) and injected
through a hyposdermie needle. The fastest route i inravenous (IV) injection
jection into avein. The drug immediately enters the bloodstream, and itreachesthe
brain within afew seconds. The disadvantages of TV injections ate the increased care
and sil they require in comparison to most other forms of injection and the fact
that the entre dose reaches the bloodstream at once, Ian animal is especially se
sive tothe sve litle time to administer another drug to counteract

(on, in some cases, suspended

iseeen,
An intraperitoneal (IP) injection rapid but not as api asa IV injection. The
<deugis injected through the abdominal wall into the perineal avi — he space that
isthe stomach, intestines, ver and other abdominal organs IP injections
‘most common route fr administering drugs to sal laboratory animals. An
intramuscular (1M) injection is made direc io Large muscle, such as those Found
in the upper arm, thigh, or butocks The drug is absorbed into the bloodstrcam.
‘through the capillaries that supply the muscle If very slow absorption i desirable,
the drug can be mised with another drug (auch as ephedrine) that constriet blood.
vado ds ve low of blood through the muscle
into the space beneath the Kin, by means ofa sub
ection useful ony if small amoun
istered, because large amounts would be painful Some at
Soluble drugs can be dissoked in vegetable oi and administered sabewtaneous Ia
this case, molecules of the drug wil slowly lave the deposit of oll vera period ol
several das I ey slow and prolonged absorption of drug isdesied, the drug can
he formed into à dry pellet or placed ina sealed slicone rubber copule and im
planted beneath the skin
‘Oral administration is he mon common form of adminisring medicinal drugs
ans. Because of the cut of geting laboratory animals 4 eat something
that does not ate good to them researchers som use this route, Some chemicals
‘aot be administered orally because they wil be destroyed by stomach aid or de

113. geste enzymes or because
Blondurcam. For example,
administration of certain de
tongue. The drug isabsorbed int the |
‘mucous membrane that ines the mouth, (Ob

Drugs can also De admiisteredat

peri
animal. In addiion, when agitated,
‘would mean hat the drug would notre
And Fin not sure would want to try to adminis
nal Rectal suppositories are most com
gs provide
phase cocaine, and nara
Hung disorders are often inhaled in
the tangs
fects

Some drugs can be absorbed directly trou
means of topical administration. Natural or 3

rcumally smoked.

1 brain very shor, and drugs ah

stop smoking. The mucous membrane

1 the

ot absorbe rom the digestive stem

ys can he accomplished by plac
losa by the capillaries that supp the
this metho! works on with he

form of pearl. lntareca dination is rey usd ge drug to ex
cal animals For obvios reason ths process woul be fia wa st
rau sas tendo defeat lich
sn in place long enough
areca soppontory o
ony wed o sine rg hat igh

for drug imitation inhalation. Nico
dition, drugs used to treat

the form fa vapor or fine an
istered his way have very rapid

the sin, so they ean be give

ici steroid horm

initered this way can nicotine (asa treatment to make it ear
sal passages also provides a

ee >

bins admision u
Ina Ramona
sr br
op séminuten Asn:
1 | faton fase ducs
nano nen

e, | intacte IC)

tongue.) Nitroghcer.
dy by people who

digestive toc

bc or.
Tange

The route from

sea be ad
a person to

cute for topical administration. Commonly abused drugs sich as cocaine hy

‘rochloride are ofen sed so that they come

‘This route delivers the drug o the brain very rapidly. (The technical rately wed

ane fr this route ls ¿nai And note at n
‘don; when pondered cocaine is nifed, ends up
asa passages, not in the ngs)

aly

isnot the same as mala
the mucous men

brane ofthe

ugs can he administered dirty into the brain. As we savin Chapter

2 the blood-brain barter prevent certain chemicals (rom leaving capilarcs a en

ng the brain, Some drugs can
each the brain, hey mnt be injected direct into the
rain or into the eerebronpinal id in the bra
ular stem. To study the effects ofa drug in
region of the brain (for example, in a particular nucle
‘ofthe hypothalamus), a seseacher vil neta very small
amount ofthe drug diecty ito the brain. This proce:
‘ure, nown as intracerebral administration, is described
‘more detail in Chapter 5. To achieve a widespread dis
tubuion fa drug in the brain, a researcher wl get past
the blood-brain barrier by injecting the drug into acere-
ral ventricle, The drug is then abnorbed into the bra
roventriculr (ICY) administration, i sed very rarely
umans—prinaily to deliver antibinis direchy 10 the
brain vo rat certain ypes of infections
€ 4.1 shows the time course of blood levels of a
commonly abused drug, cocaine, ltr intravenous injec:
on, inhalation, siffing, and oral administration. Th
amounts received were not identical, but the graph ls
trates the relative rapidity with whieh the drug eachesthe
(See Figure 4.)

specific

ros the loodl-brin barre, ese drugs are

he concentration of one ios plasma fer inver
ion intalaton fing ond rl agas,

Tie in)

‘and van Teor Mee aod One TOT ARS

114. ITA. harten 4: postor, rr abongman comenten

Distribution of Drugs Within the Body
As we san, drugs exert ther effects only when they each hei sites of ae
the ease of drugs that affect behavior, mow of these sites are located on or
ticular cells inthe central nervous system. The previous section described the rones
by which drug can beim int he bs Wi iracercbral
or intracerebronentricular adminis sin the route of drug ad
‘ministration vary only in he rate at which drag reaches hats
‘the liquid par ofthe blood). But what happens ne
that are of interest to psychopharmacologi He outside the blood vesch
Several factors determine the rate at which a drug in the Bloodstream reaches
‘within dhe brain, The fir is pid solubility. The blood-brain harrier
Is for watersoluble molecules, Moleeules hat are soluble pda pass
through the cells that line the capillaries inthe central nervous sem, and they
‘rapidly distribute themselses throughout the brain. For example, diacestmonphine
(more commonly known a heroin) is more lipid soluble than morphine i Thus
avenous injection of heroin produces more rapid effects than docs one of
molecules o dhe two drugs ate equally effective when
ach thei sites of action in the bra, the act that heroin molecule get there
faster means that they produce a more intense “rsh” and this explains why drug
addict preter heroin to morph

jon the

Inactivation and Excretion

Drugs donot remain in the body indefinitely. Many are deactivate by enzymes,
all are eventually excreted, primarily by the Kidney, The ver plas an espe
{lly active role in ensymatic deactivation of drugs, ut some deatvating enzymes
are also found in the blood. The brain also contains ensymes that destroy some
drug. In some cases enymes transform molecules ofa drug into ther forms that
Ahemsckes are biological active. Occasionally, the transformed molecules is en
mmoractve than the one thats administered, In ach cases the elfect ofa drug can
have a very long duration.

Figure Drug Effectiveness

A éme rome ae nessa songe doo Drugavar wich in thir efeetienese A mall dose o relate
tner produ nens ge ec eme ete rg can calor exceed the fc larger amount of
ed Aw ht me,” elate infected, The bes way to mesure the cine
e o meme’ ess ofa drug to plot doseresponse curve To do hi sueca
pain ae en various doses ol drug ul defined as milirams of

non

eect ot 9

arog per og of her Boch weg ane ecole
rug are pled, Becas he molecules of mos drugs diste
themaces throughout te lod and then throughout the reso
the body a hate lec (haman o aorary animal) vil y=
EN realanger quan ola achieve these concentration
ri et amaler ject As Figure 12 shows incre roger
Eee Gone drug ease mer larger ects, nl the point of
taxman effect reach. Arts pol, creasing the dose of

the drag does ot produce any more effec. (Be Fire 4.2)
est drugs ha more than oe effec. Opts char mor
phine and codele produce algu (rece actas pale.
Batty ao depres te ac of neurontin the medula tha co
tol heat ae and relation A plan who precisan opr
se opere pallens pala vans la doe tat sr

Dour oran Tigh enough to produce analgesia but ot enough to depress car rate

and respiration—effects that cou be fat Figure 4.3 shows wo

115. dose-response curves, one forthe analgesic eects of a
painker and one for he d sant feet on res.
piro, The difference between these curves indicates
the drug's margin o set. Obnion; the mont desirable
ese ange margin of es See Fe 43)

ing doses ofthe drug o à group of laboratory an
mal sch as mice. Two numbers are obtained: the dose
that produces the desired effets in 30 percent ofthe an
imals and the dose that produces toxic effects in 50 per.
‘ent of the animals The therapeutic index isthe rato of
these wo numbers. For example if the toxic dose ls fe
times higher than the effective done, then the therape
tic index is 50, The lower the therapeutic index, the
more care mus be taken in prescribing the de

‘angle tel

‘deger—a low as 2 oF ln o

humor am have deren nds wel mer
100. Ava consequence, an ciel menton oa har
Bitrate smc more Hel o a wag effects han à
Siar overdose af run os Val
May do drags ary inte eletnenes? There are
‘wo reno Ft rent gen ose with the
ame bein eur any hare dierent nc of >
Gen. For cap, bok morphine an spa have mar
fit sa ta moine supprenc the sco of
euro the pital cod and ri dat riche in
mpi reduce he production of chemical ave
irom damaged tw palmes
mb gn done of morphine exprenedn tem ol ml
gram of boxy neigh) produces mich more pin rc
' The second reason that drugs vary in their effec
ib og vith trate of scone wil ace in
Slope drug of nett pelle na

live neurons. Because

ing wi other molecules located in the central nervons semi presynaptic or

Mini will produce fle
two drugs with identical sites faction ©
erent affinities for

case mont rg
ite tes of ation and Tow amis for
limi for ites a ation tht produce
tact

vers The
rape

that produce toxic ide effects One of the goals
aies find chemical with just this pattern of elects,

Effects of Repeated Administration

Otte, when a drugs administre repeated is fees wi
most ess cul din p
ang becomes more and more fleche phenomena

achete readiness wih which th

up effets, a drug can have igh alfiniis for some of

enomenon known as tolerance.

Pumps 08 Psynopharmocoiocy MI

Dose response cre fr the nage fc ot morphine and
forthe dos ae ie etc, depresion ei on
Fern Auge margin oe afec y no
lerne between a doe report u for epee
‘thc andor aaa ec

so
EE
San
g tatty
3
|
5|
| (De ospanse
ere
Seo tec
‘Serine on
Fe
‘ow Dose ca >

pain perception, where

e drugs act ver ier
iigrams o drug per Milo.
on than the same dose of

ssto dowith the
major section of this
exer ther elect by bind

sat relatively low com
in relatively high
an vary widely in their eF-

on, be

herpetic index Te abe
no ata 5 pac
ote sara

fin Mere vt
‘eter

‘raters pe

sites In ai

desirable drug has a high,

I iteetsand a ow ality for sites

“of research by drug con

{not remain consam. In

oer exes
known as sensteation.

116. BET warren 2: comme, sw ablorgman cometen

lea symptom Ten
Shore a
bese rar
ten

Babe se) nr
Sse buts gen oon
nm testa pica
Se ang ved esperma
cn ve el men
Pe

Let's consider tolerance first. Tolerance i seen in many drugs that are com

mon abused. For example, a regular er o heroin mus take larger and langer
‘a

for ito be effective
‘enough to develop tolerance
ic or she suddenly tops taking the drug. Wiherawal symptom are primari the
‘opposite of the effects ofthe drug sel. For example, heroin produces euphoria
‘of anions misery (Eupharia and
respective) Heroin produces com
Stpation: withdrawal from it produces nausea and cramping. Heroin produces re
Taxation: withdrawal fom produces agitation
‘Withdraval symptoms are caused bythe sme mechanisms tha
for tolerance, Tolerances the result ofthe boxy atempt to com
Feetsof the drug. Thats, most systems of he body, including those controlled by the
do that they stay ata optimal valve, When the elects of drug
isms begin to pro
om, at eat partially compensating forthe distance from
aalue. These mechanisms account for the fact that more and marc of the
à be taken to achieve agen level of eects, person stops
drug he compensa ‘unopposed by
the action ofthe drug
Research suggests that there ae several pes of com
swe vil sce, many drugs that affect the brain do so by binding with receptors and a.
rating them. The fist compensatory mechanism involves decrease in the efec
Sens of sich binding. Ener the receptors become ls sensitive othe drug (hat
is their affinity forthe drug decreases) or the receptors decrease in nun
second compensatory mechanism invokes the proces that couples the receptors to
the membrane or to the production of second messengers A
ion ofthe receptors one or more eps inthe coupling process
become les effective. (OF course, bth effects can occur.) The details of these com
ppensatory mechanisms are described in Chapter 16, which discusses he cates
ects of drug abuse
As we have seen, many drugs have several tes faction and ths pro-
¿duce several ferent effects, This means that some of the effects of drug may
show tolerance but others may not, For example, harbiturates case sedation and
ako depres neurons hat contol respiration. The sedative elects show tolerance
ba the respiratory depression does mot, This means tha larger and anger doses
fa barbiturate are taken to achieve the same level of station the person begins u
Fun the ik of aking dangeronsl lage dene ofthe drug,
sation sof course, the exact opposite of tolerance: Repeated doses of a
“drug produce larger and lager effects Because compensatory mechs tnd to.
correct or deviations aay rom clogical processes, sen
Sization iles common than toleran ets of drag may show
«others show tolerance. For example, repeated injections of co-
‘caine become more and more likely to produce movement disorders and conve
Sons, whereas the euphoric eects ofthe drug do not show vensizuion and may
en show tolerance.

Placebo Effects

A placebo isan in € that has no specific physiological effect The
‘worl comes from the Latin par, “to please.” phycian muy sometimes ge a
placebo 10 anxious patients to placate ther. (Yow ean sce that lara alo hs the
ame roo.) Butalthngh placebos have no sper physiological effet tis incorrect
Lo say that they have no effec. Ifa person thinks that a placebo has a physiological
‘fect, then acminisraion of the placcho may actually produce that elec.

e responsible

ensatory mechanisms, As

117. ‘When experimenters want ta investigate the behavioral effects of drugs in h
mans, they mus use contol groups whose members receive placebos, they
ot be sure that the behavior effect they observe were eased by specific effects
‘ofthe drug, Santis wih laboratory animals must alo se placebos, ven how
need not worry about the animals “elef about the elects of the drugs we give
them. Consider what you must do to gear an intraperitoneal injection ofa drug
ou reach into the animals cage. pick the animal up. hol tin such away tha is
bomen is expose and its head positioned to prevent i from biting yon insert
ypodermie needle through is abo the plunger ofthe ring
replace the animal in hs cage, being sur to et go oi quickly so that cannot
cuis the experience of

tur and bite you, Even if the stn
receiving the injection would cite

the seretion of sires hon 1 have other physiological efe
he behavioral effects ofa drug are, we must com

other animals who receive a placebo administered in exacı the same

‘vay as the drug, (By the wa a billed and experienced researcher can handle a at

INTERIM SUMMARY

Principles of Psychopharmacology
Pachophammacology ithe study ofthe effects of drug onthe nervous stem and be.
ior Drugs are exogenous chemicals ha are nt cesary for norma celular functioning
‘that sigan alter he functions of certain cls ofthe body when taken in lative ow
doses. Drugs hate effects phyiologlcal and behavioral and they have sites of action mot
‘cules ith which they interact produce there effects.
Pharmacokinetics isthe fate of drug sits absorbed ito the ody cultes hough
‘out the boy. and reaches its sites faction, Drugs maybe administered by invavenous. in
"apertneal, intramuscular and subeutaneou jection: they may be administered ral,
Sublingual, intarctly by inhalation, and topically (on kn or mocous membrane: and
‘they may be injected intracerebral or ntacerebroventiclay, Lipid soluble drugs easy
5 tough the blood-brain bare, whereas others as thi bare slowly or ota al.
The dose-response curve represents à drug effectiveness relates the amount ad:
ministered (usally ln miligrams per logram ofthe subjects body weight) 1 the resulting
(ec. Most drugs have more than one ste of ation and therefore more than ane elec
“The satety ofa drug measured by the ference between doses that produce desrable et
{ects and those that produce toxic side eects Drugs vary In the effectiveness because 01
the nature oftei tes of actions andthe atin between molecles ofthe drug and these
ste faction.

Repeated administration of a drug can cause either tolerance, often resulting In with
dranal symptoms, or sensitization, Tolerance can be cute by decreased any of a drug
‘ith its receptors, by decreased numbers of receptor, or by deceated coupling o receptor:
th the Bechemical tps it contra. Some ofthe effects of à drug may show tolerance,
ile others may not—ot may even show sensitization

{ew animals—prodce chemicals hat act on supe, (OF course, the people ml
Kew nothing about neurons and synapees) Some of
cable elects others have heen tse

Sects on MT

118. IT carrer como ‘wovablongm consten

See Animation 1, Ae
Bl
te wan that ru cn tet
separation

an pe o
ais at cates
‘betes pora eso.

nes, reduce pain, or poison ather animals (or enemies). More recently ch
‘emis have learned to produce completely artificial drugs, some wth ponences ar
eater than those ofthe naturally occuring ones The traditional us of drugs re
dion, they an be used in researc laboratories to investigate the op
servus stem. Mont drugs that affect clio do so by alecting
affect synaptic transmission are clasifica into 140
general categories. Those that block hilt the postsynaptic elfectae called an
{agonists. Those that facilitate them are called agonists (The Greek word agın
test" Thus, an agmitis one who takes part nthe contest)
This section will describe the basic effects of drugs on sai activi: Recall
fom Chapter 2 and Animation 23 thatthe sequence of spe acini goes lke
thie Neurotransmitters are sy synaptic vesiele. The synaptic
veo y become docked. When an
axon fires vltagedependent cae presynaptic membrane open,
the entry’ of calcium ions. The calcium fons ite the release ul
oler ino the ssaptic
with pontnaptie receptora, casing particular ion channels to open, which pro
¿luces excitatory or inhibitory pompe potentials, The effects of the nero:
transit are kept relatively bet by their euprak by transporter molecules in
presynaptic membrane or by thei destruction by enzyme. In addition, he simula
on of presynaptic autoreceptors regulate he hen and release of the ncuro-
ansmite. The discussion of the elects of drug in this action follows the se
Pas sequence. All ofthe effects 1 will describe are summarized in Figure 4 wi
some details shown in ational figures should warn you that 0
are complex, so the discusión that follows bears cael
ou sty Animation 4. Actions of Drags, which reviews

Effects on Production of Neurotransmitters

‘The fist step isthe synthesis of the neurotransmitter ron
cases the rate of sess and ele of a neuroran
cursor is administereds in these cases the

transmite from being produced. Such a drug serves as
in Figure 44)

Effects on Storage and Release
of Neurotransmitters

Neuronransmittersare stored in synaptic vesicles, which are transported othe press
naptie membrane, where he chemicas ae released. The storage of neurotransnit
ters in vesicles is accomplished by the same Kind of transporter molecules that are
responsible for reuptake of à neurotransmiter into a terminal button, The tra
porter molecules are located in the membrane of synaptic vesicles, a
to pump molecules of the neurotransmitter across the membrane fi
«lex, Some of the transporter molecules tha fill smaptic vesicles are capable of be
ing blocked by à drag Molecules of the drug bind with a particular site
transporter and inactivate i Beca the spi vesicles remain en
released when the vesicles eventually rupture agains the preymaptie membrane.
The drug serves as an antagonist (See step Sin Figure)

Same drugs act as antagonists by preventing the release of neuro
from the terminal button. They do so by deactivating the proteins that cause sp

119. Siero Oros ton ME

‘summary the oyo in wie scan affect api tanumiion AGO = ago
AT 2 antagonist NT nurture Drops hata a apo are mata nl: rs

‘hat acs atagoit are mare inte

CES

nd expel their content into the
eet They acasagoni by bin
miter. (See

ssnaphic left, Other drugs have just he oppos
ing with these proteins and direc wiggerng release ofthe neuro
steps Hand 5 in Figure 4.4.)

Effects on Receptors

“The most important—and mos complex—site of
tem ison receptor, both presmaptic and postsynaptic, Let's consider postsynaptic
receptors fit (Here is where the careful reading should begin) Once a ncuro-

released it m silat the pontsmaptic receptors, Some drugs bind
ese receptors sta roransmiter does. Once a drug has bound with
the receptor it can serve as ether am agonist or an

on of drugsin the nervous y

eue of

eurotramsminer is present Tons then pas hough these
nel and produce postsmapti potential, (See step 6in Figure 44)

Drugs that bin with postsynaptic receptors an ls serve as antagonists. Mole-
‘ules of sich drugs bind withthe receptors but de
‘use they oceupy the receptors binding sit, te neurotransmiter
{rom opening the ion channel, These
antagonists (See step Tin Figure 44)

eng sn
arca oon
gi am bce eh e
diet anagoi Aon
Res

120. ITA charter a: pcroprrmacoio wor ablongman comcaronó

AGT EP LS

Actors of drugs a ending ts an receptor 0) Competive bing Des apni and
Sgen rec on the neuroma nag so.) Nonompestre Bud,

Peep meatal emanate
teng
oo TT ong Loc ope Me one tasers
compe
aes perra

o

yg sites to whieh ferent igands can a

bind with one site, and other substances

ous drugs) bind with the others. Binding of à

‘one ofthese alternative sites efered Lo as noncompetitive bind.

ing, because the molecule does not compete with molecules of the neurotransmit

ter for the same binding it. Ia drug attaches to one ofthese alternative sites and

prevents the fon channel fom opening, the

ist. The ultimate fect ofan indirect

‘nist, but its site of action different, I ad
‘ofthe ion channel, ifs to be an indirect ago.

selectively activate presynaptic receptors act as antagonists. Drugs that Hack pres
haptic autoreceptors ave the opposite effect They nenas the release of the neun
inmi, acting as agonists. (Refer to steps 8 and 9 in Figure 4.4.)

roncngerive vis es. | Effects on Reuptake or Destruction
Ea | of Neurotransmitter

“The nexı step after stimulation ofthe poxssnaptic receptor i termination of
postsynaptic potential Two processes accomplish hat task: Molecules ofthe neuro-
transmitter are taken back ino the terminal button through the proces ofre

Goo va megane | or they are destroyed by an
BEE va co, e process Inthe
sere win e berg tel | that are responsible for

Ve incor. second case molecules oft
Inde agonist Aso ta | eunoiranın

sienne | pe ot sch
cum acia one | SS bou pes of dns pro
Sorgen

Glee

121. INTERIM SUMMARY

Sites of Drug Action

‘The process of snaptitransmision entails the thesis oftheneurotranmite ts storage
in synaptic vesicles, release into the synaptic def. its interaction with postsynaptic re
‘ceptors and he conequent opening fon channels inthe postsynaptic membrane The ef
{ects of the neurotransmitter are then terminated by reuptake into te terminal Button or
by eneymati deactivation,

Exch ofthe steps necessary for smaptic wansmision canbe interfered with by drugs
hat serve as antageniss and few ofthese steps can be simulated by drugs tat serve as
agonists 1 partiel drugs an increase the pool of salable precursor block a ios
{enzyme prevent the storage of neurotransmitter inthe opti veses simulate Block
the lease ofthe neurotransmitter stimulate o block presynaptic or postmaptc receptor
retard euptae, or deactivate enzymes that destroy the neurotransmiter pstsynoptially
or resmaptcaly A drug tat atte postsynaptic receptor serves aan agent ren
‘ne tat activates presynaptic autoreceptors seres a an antagonist. drug thet blocks
ostyaptc receptors serves as an antagonist, wheres one that blocks autorecetor serves
an agonist

Because neurotransmiters have two general efec on postsynaptic membrane—
vation (EPSP) or Iwperpolarizaion (IPSP}—oste might expect tht there
would be two kinds of neurotransmitter, excitatory and inhibitors. Instead, there
are many different kinds—severl dozen, a leas. In the brain mont synaptic com-
‘munication is accomplished by two neurotransmitter one with excitatory effects
tamate) and one with inhibitory effects (GABA). (Another inhibitory nero.
is found in the spinal cord and lower brain stem.) Mot ofthe
oles balances between the excitatory and in
hibitory effects ofthese chemical, which are responsible for mos of the inform
ted from place to place within the brain In act, there are probably no
‘do not receive excitatory input from ghiamatescereting

tory input from neurons that scree ©
cine. And wth the exception of neurons that detect painful simula sensory or
ani information tothe axons whose terminals release gh

fects rather u
transmitters other than gla
Cuts of neurons hat are
secretion of aces
{he information that ea
hances rea
‘certain categriesolspeiestypcal behaviors and red
act Impulse Secretion of dopamine in some regions ofthe brain generally
sty monements but doesnot specify which movement wi cc In
‘ther regions secretion of dopamine reinforces ongoing behavior and makes them
more ikely to occur at ter time, Because particular drugs can selectively affect
neurons that secrete particular neurotransmitter, they can have specific eflets on
Behavior:

es the cerebral cr

x and faciles learning, but
ed by neurons that ee

ello hat the an

122. IT carrer :esootormaccos, worablongman comasanée

econ sen acte
eine acera
OA taro ans
fect eco a Yates
teat an ae con
be ato ne podas ve
erase sajones
‘racer rag pe
‘ers eae yemas bar
‘ack widow pde venom a
pan roa y ee
‘sow ice et age ee
join

og onen
Sanaa

Mode pra sum
So nee Bote ty
mac rcpt sain
19 moe ani
Ro ts Rs y mu
Ge nd bose by ope

Tre bonnet of cele.

a“

o»

This section introduces the most Important neurotransmiters discuss some of
their behavioral functions. and describes the drugs that interact with them, Aswe sur
inthe previous section o this chapte, drugs have many front sites of action. FO.
{nately for your information-procesing capaci (and perhaps your sani), ot all
types of neurons are affected by al pes o drugs. As you il ee, that sl leaves a
mber of drugs to be mentioned by name. Obi some are more impor
‘others, Those whose effects describe in some deta are more importa
‘han those T mention in passing. I yon want to leur more details about these drugs
(and many other), you should consul an uptodate pochoparmacology text.

Acetylcholine

Acetone ithe primary neurotransminer secreted by efferent axons ofthe ce
tral nervous sytem, All muscular movement is accomplished by the release of acts
‘choline, amd ACh also found in the ganglia ofthe atonomic nervous stem an

‘the target ongans of the paragmpathetc branch of the ANS, Because ACh ls found
‘outside the central nervous system in locations that are as to stud his heurte
Inter ws the first to be dnconered, and it has received mu from euro
scientist Some terminology: These ynapserare said o be allie Egon isthe
Greck word for "work" Thus, dopamine synapses release dopamine, sonny
synapses ease serotonin, and so on. (The sus pis pronounced "ur ik)

The axons and terminal batons of acescholinergic neurons are distributed
widely throughout the brain. Three systems have received the most attention from
Ficuroscientiss those originating in the dorsolateral pons, the basal forebrain, and
the media septum The effects of ACH released inthe brain are generally aitor
“The acetylcholinergic neurons located inthe dorsolateral pons are responsible for
citing mos of the characterises of REM sleep (the phate of sleep during which
‘reaming occurs) Those located in the basal forebrain are involved in activa
the cerebral cortex and latin learning, special perceptual learning. Those
located in the media septum control the electrical sy o the hippocampus and
‘modulate its functions, which include the formation of particular hinds of memories

Acetvicholine is compened of two components dln, a substance derived rom
{hebrew of lipid and aa he anion found in ina, also called acetic a
‘cette cannot be attached dec to choline: instead, e is transferred from a mole

tule of ar Cas, Con (coenzyme A) ia complex molecule,
«onsisingin part of the vitamin pantothenic acid (one of the
1 vtamins). Co is produced by the mitochondria, and it
takes par in many reactions dhe body AceghCoA is imp
CA with an acetate ion attached 0. ACh is produced by

con ui acetyltransferase (ChAT), the acetate ion is transferred from

chemical reactions, Think of acetate as a hot dog and
hole as bun. The tsk ofthe person (enzyme) who op
‘rates the hot dog vending stand ito puta hot dog nto tte
"han (make acesicholine). Todo so, the vendor needsafork
1) to remone the ot dog from the boing water,

the hor dog (attaches ac-

log rom fork to bn

and the venom of the
back widow spider, lit the release of acescholin, Bat
aline toxin i produced by «rida botulinum, a bac

123. um that can grow in improperly canned! food. This drug

prevents the release of ACH (sep 3 of Figure 41. The drug

‘once called that a
oul kl the world sen
tio. You undoubtedly know that tx rat
nt has become Fshionable A dite (obvio!) solution of
Banulinum toxin is injecte into people facial muscles to stop

‘scar contractions that are causing wrinkles, In contras
black widow spider venom has the opposite effect: I stimltes
the release of ACH (sep 4 of Figure 4.9, Although the effes
of black widow spr venom cam also be fatal, the venom is
‘much les toric than botulinum toxin. In fat, most healthy
adult would hive to receive several bites, but infants or Fra,
er people would be more suscep

‘You wil ell from Chapter? hat alter beng released by
terminal button, ACh is ceactnated by the enzyme ace

cholinesterase (ACHE), which i present in the postsynaptic
membrane, (See Figure 4.2)

Drugs that deactivate ACHE (sep 11 of Fi
Some are cd as insecticides, These drugs re

cher mammals, because our blood contains en

SGU TER

‘The derctan of sean by chaines

> .
seen e:e
sewn

=
Boni mec

Bee

rents apart
rosie

144 ae wed for several purposes.
ly Ail insects but
that destroy them. (sects

lack the enzyme) Other ACHE inhibitors are used medical, For example, a here

itary disorder called matin gris caused by
tem against aces

comes weaker and weaker asthe m
Aransmiter. I the person is give

som wil regain

pro

onged effect on the remaining receptors. (For

stack of perso

1 receptors located om skeletal muncen.

Jos become less responsive to the neuro-

‘an ACHE inhibitor such a neostigmine, the per.
‚me strength, because dhe actycholine that i released

nately neosignine «

The person

‘row the blond-brain harrier, o does non affect the ACHE found in the central

There are two different types of ACH receptors—one ionotropic and one

ottopic. These receptors were ented hen invest
ators disconered that diferent drugs activated them (sep Got
Fiqure 4), The ionotropic ACh receptors stimulated by nic-
tine, a drug found in tobacco leases. (The Latin name of
plant is Nieetiniana talacum) The metabotropic ACh recep
Festimulated by musearine, a drug found in the poison mush
room Amanita muss. Consequemtl these two AC

tore are refereed to as m

receptors, respectively. Because

contact rapidly, they contain the rapid, io
receptors

Because muscarinic receptors are metabotropic in nature

and thus contol ion channels through the production of cc

esenges their ations are ower and more prolonged

than diese of nicole receptors The central nervous system

contains both kinds of ACH receptors, but muscarinie recep.

wotrapie nicotine

{ors predominate, Some nicotine receptors are found a ano
one maps in the brain,
action

Jus as two different drugs stimulate the two clases of
aceilcholine receptors two different drugs Mock tenn (step 7
of Figure 41). Both drugs were discovered in nature long,
ago, and both are sll used by modern medicine. The Birt

124. RER cuartos 4: conne worwablongman.comicansonse

step tope) Aa
fas none eine
stilo cata om

Soom rond
eran pa)

OPA es ape) eee
re nm on
Mantes
‘imine ne
Doit non
ang ne mor
mc e ción
stoic en ee 20
BO agent sommnege
fewer erat ne ve
mi
mesocria system ce o
Kero Asptem! dpi
‘Singin pl coe
Patients dete A ely:
overs coe y due.
tonal me mgmt em

Table 4.1

atropine, blocks muscarinic receptors. The drug named after Atropos, the Greek
fate who ut the trad of fe (which sufficient dose of atropine will certainly do).
Atropine is one of several Madonna alkaloids extracted rom a plant called the
ightshade, and therein lesa tae, Many years ago, women who w

increaetheiratractivenessto men put drops containing belladonna alka

reyes ac, lada means prety tad" Why waste drug used this va
‘One of the unconscious responses that occurs when we are interested in something,
isdiation of our pup. By blocking the effects of acewvicholine on the pupil be
Tacoma alkalis such a atropine make the pupils diate. This change makes a
woman appear more interested in a man when she looks at him, and, of course, his
Apparent sig ofinteres makes him regard her as more aurscihe

Another drug, rare, blocks niotiie receptor. Because these receptorsare the

Tike botulinum toxin, eases parabsis. However, he

lec curate are much Ester. The drug isextracted from several ferent species
‘plans Found in South America, where vas discovered long ago by people who
edt 0 coat the ip of arr and darts, Within minutes of being truck by one of
ese pois an animal collapses, ceases breathing and dies Nowatay, curre (ad
‘other drugs withthe same sit of action) are use to parahze patients ho are to u
“ergo surgery so that heir muscle wil relax completely and not contact when they
te cut with cape An anesthetic must ao be wed, bee
‘nly curar will remain perfectly con sense o pain, even though parse
Tyee. And, of come, tespirator mate wed to supp a tothe lung

The Monoamines

Epinephrine, norepinephrine, dopamine, and serotonin are four chemicals that bee
Tongo family of compounds called monoamines Becas the molecular sructures
‘ofthese substances are sini, some drugs affect the activity of al of then to some
{degree The fit three—cpinephirine, norepinephrine, and dopamine —belong to
Asubclasof monoamines called catecholamines. licor learning the ers
in Table AL because the willbe woe many timos throughout the rest a this book.
(See Tablet.)

‘of these stem co

are produced by several stems of neurons the brain. Most
sit of a relatively small number of cell bodies located in the
cls epeately and ge ie to an enormous number of
rnughout many regions ofthe brain, Monosminer-
dulte the function of widespread regions ofthe brain,
activities of particular brain functions

ie neurons ih

Dope

Theft catecholamine Table 1, dopamine (DA), produces od excitatory and
ntibioryponsmapti potential, depending on the poxsaptic receptor: Dopamine
‘Rone ofthe more interesting neuroranmitten because it has een implicated in se
ral importa funcio including movement, ing. and
the reinforcing ect of drs that people tend to abuse therefore, it

esc in Chapter 12, 14 13 ad 16
The synthesis ofthe catecholamines is somewhat
‘ated than that of ACH, but each sep sa simple one. The precursor
molecul is moxie slighty step by te, ut achieve final

ach sep is controled bya diferent enzyme, hic

“snl part to be added or taken of. The precursor forthe two major
“catecholamine newrotranmitters (dopamine and norepinephrine)
À min esental amino acl hat we must obtain rom our die.
An came converts tyrosine into LDOPA. Another enzume converts
TDOPA into dopamine. In dopaminergic neurons that converso

125. ‘hoy are dead by the mance onder found in

is the lat ep, but in noradrenergic neurons, dopamine &
cphrine. These reactions are shown in Figure.

The brain contains several stems of dopaminergic neurons. The three most i
portan of these originate in the midbrain. The cll bodies of neurone of the ni
Frostriatal system ar locate in the substantia nigra and projet ther axons to the
contrat the date nucleus and the putamen, The neostriatum is an impor
‘ot neurons ofthe mesolimbic system ae located inthe ventral tegmental arca and

eed ino norepi

tant part ofthe basal ganglia, involved i the con

of the Imbie system, including the muscles
accumbens, anal, and hipocampo. (The term meso rfers tothe midbrain, or

mesenecphalon.) The nucleus accumbens plas a importan role in the reinfor

ing (rewarding flees of certain categorie of sim, including those of drugs that
people abuse. The cell bodies of neurons o

the mesocortca system arc alo located
in the ventral tegmental area, Their axons projet 1 the pretron
neurons have an excitatory effect onthe ronal cortex
tions as formation of shoreterm memories, planning, and strategy preparation for
Problem sling, (Sce Tale 4.2)

Degeneration of dopaminergic neurons that connect the substan
the eatlate clus cases Parkinson's disease, a movement disorder characterized
by temors, rigidity ofthe limbs, poor balance and die ln initiating move

nd tas acc sh fünc

ments The cell bodies of these neurons are located in a region of he rai called

the sulsantia má ("ack substance"). This region is normally stained black with
‘melanin, the substance that gives color to skin This compounds produced by the
breakdown of dopamine. (The brain dam

age that causes Parkinson's disease was
discovered by pathologists who observed thatthe sibsantia miga of deceased
person who ad had this disorder was pae rather than black) People with Pain
os disease are given -DOPA, the precursor to dopamine. Alhaugh dopamine
cannot eros the blood-brain barrier, -DOPA can, Once 1-DOPA reaches the
brain, vital up by dopaminergie neurons and in converted o do

amine (sep 1

| Figure 4.8.

“Y ou

Y Kam

Dcpamne
4, kan

126. BID cHArTeR a: rycncohsemacoiogy worm ablongman com/eationbe

yl one hi
resina ee super) A
meget nen en
monoamine oxide (MAO)
ohne aan
pr pp and an
iets ne amy oF NO;
as ogame a

‘of Figure 14). The increased synthesis of dopamine cases more dopamine to be re
Tease by the surviving dopaminergic neurons in patents wih Parkinson disease,
Asa comsequence, the patients symptoms ar allesited

‘Another di

rg interferes with thea ne (and of norepinephrine, aswel) it
serves asa catecholanine antagonist. The drug is not normal used medically, but
has been wed asa research tool in laboratory animals,

The drug reserpine prevents the storage of monearincs in synaptic veces by
Docking he wansportersin the membrane that pump monoamines int dhe vesicles
(step of Figure), Because the sap veis remain empay no meurotra
teri eksse when an action potential reaches the terminal button Reserpine he
isa monoamine antagonist. The drug which comes rom the rot of a shrub, was dis
‘oncred ener tice thon cargo in India, where cs fondo bus ica
ing nakehie and seemed o have a calming lc. Pieces te soo are sl sol
markets in rural arcas ol nia ln Western medicine reserpine was previo sed to
At ig blood presse, bi has been replaced by drugs with ewer side elects

‘Several diferent pes of dopamine receptors have been identified, all
metabotropic. OF these two are the most common: Dy dopamine raptors and Dy
“pain pion. I appcan that D, receptors are exclusively postsmapic whereas
Dz receptors are found both presyaptically and ponsyapticall inthe Brin. Sex
cal drugs stimulate or block specific pes dopamine receptors.

Several drags inhibit the reuptake of dopamine, us serving as pote
dopamine agoniss (step 10 of Figure 14). The est known of these drugs ae am
plictamine cocaine, and me ph esting eect
eases the release of both the rane
porters for these neurotransmierstorum in reverse, propelling DA and NE into the
Sapte cleft. Of course, this action alo blocks reuplake ofthese nenrotransmiters
Cocaine and methytphenidate simply block dopamine reuptake. Because cocaine
alo blocks vllagedependent sodium channch, its sometimes used as topical
anesthetic, especial inthe Form of exe drops or eye augers Meihylphenidae (Ri
tal) i une to teat children wth attention deficit disorder

he production ol the catecholamines is regulated by an enzyme called
monoamine oxidase (MAO). Thin enzyme is Found within monoaminergic terminal
Bustos where it destroys excenive amounts of neurotransmiter. À drug called de-
‘pret destroys the particular form of monoamine oxidase (MAO-B) that Found

127. in dopaminergic terminal buttons. Because deprenst prevents
‘dopamine, more dopamine is released when an action potential reaches the terme
ral button, Thus, deprens serves as dopami

MAO is also found in the blood, where it desctvates amines that are present
Foods such as chocolate and cheese; without such deactivation nes coul
‘cause dangerous increase in blood presse

Dopamin has ben implicated asa neurotransmiter hat might be involved
Schizophrenia, a serious mental disorder whose symptoms include Hallucinations,
Aehusions and disruption of normal ogical thought processes Drugs sich aschlor.
romaine, which block D, receptor alleviate these smpioms (sip 7 of Figure
4). Hence, investigators have speculated that schizophrenia is produced by ener
actin’ of dopaminergic neurons. More recently discovered drugs such as lozapine,
may exert their herape

aman pos
elects by Blocking D, receptors The physiologyofschi. | Zenon o conteo

ale en,
ee

— oes
AS ER
ee | nolo isis)

Should note tht the terms ‘Adrenalin and epinephrine ae ymonymons, as are non | min Bedia,
“malin and norpinephrine. Let ne explain ws. Epinephrine a hormone produced | Sauer resiente
ila the central core ofthe adrenal glands, located jus abone the | foment bom agin tem
ite in the brain, but ii om.

Tor tomard Ki
Kidney. ence the term | ie net) ne
term has ben opted by pharmacologie probably becune | Sana ne Bed shame

the word Adienain vas appropriated by a drug company as 4 jener ear]
therefore oe consistent with general usage, [il eer to he thet
mompingphrine. The accepted adjectival form i noradrenergic | suppose that mamfü- | asada ow sahr à) A
Iprinesc never caught on because it takes o ong to pronounce. ‘snes a ol hee
‘We have already seen the Bose
48. The drug fasaie acid, which prevents
nephiine, blocks the producion of NE.
Almost every region ofthe brain receives input from noradren
‘The cel bodies front of these neurons are loca
region ofthe tala The ci
radrenergie sistem begin in 1

resp

ic neurons. | ecoute or ae
sen gins he and Seen,

128. DER carrer Pacman nn ablongman cometen

xen vit An est
rpm
sano tt cs
serotonin HM a wen)
oie pom
POR Ag tat is me
erat penton mn
Aone 0.0 te) à
entrain or me)
osu

Bonnes often
(Sonoran oF 4D,

"Tepepan

y game
ee

Y cam

encon
NT ann

pots. The axons ofthese neurons project to widespread regions ofthe brain. As we
ice in Chapter one effect of acıhaton of these neurons an increase in ig
Tance—atentivenes 10 events in the envranme

Mont neurons that release norepinephrine do not do so dough terminal bute
tons on the ends of axonal branches Instead, hey usualy release them through ax
‘onal variosies,beadlike swelling of dhe axonal branches. These varicosities give
the axonal branches of catecholminergie neurons the appearance of beaded
chins.

“There are several types of noradrenergic receptors, identified by their differing
sensithtes to various drugs, Actually; these receptors are usually called arnes
eplotsfather than nomdrmgireceptors because they ae sensitive o epine
(Adrenalin) as well as norepinephrine. Neurons in the central nervous ss
tain Band Badrnngemeptorsand cal aden cfr, A on
receptors are also found in varlou organs ofthe bods besides the brain and ate ve
Sponsible for the effects of the catecholamines when they act as hormones outside
the central nervous system. In the brain all autoreceptors appear 10 be ofthe 0.
‘ype. The drug idazonan blocks dy autoreceptors and hence ats a an agonist. All
audrenergc receptor are metabotropic, coupled to G protein that control the pro
‘duction of second messenger.

Serotonin

The third monoamine neurotransmitter, serotonin (also called ST, or
Saydroxyteyptamine),hasalso received much experimental attention Is behavioral
«fects are complex. Serotonin plays ole in the regulation of mood: i the control
‘feating sleep, and arousaandin the regulation of pain, Serotonergic euronsare
involved somehow in the control of dreaming

The precursor for serotonin she amino acid mptopkan. An enzyme coment
teyplophian to SATTP (iydroxvtryptophan). Another enzyme converts SHTP 10
[AT (crotonin) (See Figure 4.10) The drug PCPA (pehlorophenslalanine) blocks
the conversion of tryptophan to >HTP and thus serves asa srotonergic antagonist.

‘The cell bodies of serotonergic neurons are found in nine clusters, most of
which are located inthe raphe nucle of the midbrain, pons, and medalla. The wo
most important clusters are found in the dorsal and medial raphe nuclei, and Evil
estic my discusion to these listers. The word raphe means "seam" of "erease”
And refers othe fat that mont ofthe raphe nuclei ae found a or nea the midline
‘ofthe brain sem. Both the dorsi and median raphe nuclei project axons 10 the
‘cerebral cortex. In addition, neurons in the dora raphe innervate the basa ganglia

those in the median raphe innervate the dentate gyrus, a part ofthe hip.
pocampal formation,

Investigators have idemúlicd atleast nine diferent ypes of serotonin receptors,
1 pharmacologsts have discovered drugs that serve a agonists or antagonists for
‘man, ofthe types of SHT receptors

Drugs that inhibit the reuptake of serotonin have found a very important place

the ueatment of mental disorders The best known ofthese, Muoxetine (Prozac),
Is ned reat depression, some forms of ancy orders, and obsessie-compulsve
“soe, These disorders—and thee tratment—are discussed in Chapter 15 and
16. Another drug, fenfluramine, which causes dhe release of serotonin as weas in-
hibit its reuptake, i sed as an appetite suppressant the ‘of bess
‘Chapter 12 discuss the topic of best and ts contol by m

"Sera hallucinogenie drugs appear to produce ther eects by inter
serotonergic transmision, LSD (ser cid diethylamide) produces distortion
‘inl pereeptions that some people find awesome and fascinating but

‘ther people, This drug, which i effective in extremely small doses Sa.

direc agonist for postsynaptic ST y receptors inthe forebrain. Another drug,

129. MDMA (recht

ere agonistand!
hetamine, MDMA (popular called “eciay”) causes noradrenergic wransporers 0
Packard, this easing the release of NE and itsreupuakes This site

‘action apparently responsible for the drug excitatory effect. MDMA alo causes

Serotonergic transporters o run back Is apparently e

sponsible or the drugs hallucinogenic el scare indicates
iat MDMA can damage seroionergie neurons and case cognitive deficits.

Amino Acids

naminers I have described ae y

th à
Serotonin from the amino acid irypiophan, Some neurons secrete simple amino
acid as meurotransmiters Because aminoacid are use for protein smihesis by al
‘ells ofthe brain, difficult o prove that particular amino aci a neurotrans.
‘miter However. investigators suspect ıha at Teast eight amino acs may serve as
‘neutotranomiters in the mammalla central nervous sem, As ve sa in the in
troduction to ths section, three of them are especial important because they ate
the most common neurotransnitirs va minoburic
acid (GABBA), and ghcine

stecholamines from the amino acid tyrosine, a

Glutamate

caine ghtamate (also call guamic acd) and GABA ae found in ery in
ple organi, many investigators elev that hese neuroramemiter re the Ht
to have evolved Besides producing pompe potenti by shang post
te reception, the alo have dire enctaory el (gaie aid) and bts
effects (GABA) on axone they alo o lower the theo of excitation, ta a
foc the rate at which action potentials occur These direc effect suggest that
these substances had a general modulating role even before the eolutionary devel
‘opment of specie roses melee a
name he principal excatory neurona dina | MOA Ann ea
«or is produced in abundance bythe cell metabole procenes There soc | Cont St eno
fective way to prevent is hess without disrupting other acts of te el. | Any erdTahengere
Aisne discovered fourtypesoginamatercceptor Threcofihesere- | els
‘ceptors are tonotopic and ae named ater the ania igs that simula the | anat A arr m
the NMDA receptor the AMPA receptor, he kainate receptor The other ghite | To o ny ae
inate receptor—the metabotropic game receptor (on) metabotropic. | "een te ton
Actua here appear to beat least seve diferent metabestopiglvamate receptors, | NMOA motor A cols
tat Hie Know shout her action except that some of them serve ss psa | PU gant ee
ücauorecepior. The AMPA receptor aa | Pa ets en au

Aka sin chanel so rowers EEE

EPSPs. The kainate receptor which simule bythe drug kun aid, his similar | Ses
elle APR receptor an costo

‘The NMDA receptor has some special—and very important—characterinics. | grams ce our onto a
‘contains atlas six different binding sex four located on the exterior ofthe re- | Sadun chet sits by
‘ceptor and two located deep within the ion channel. When ti open, hc jon chan. | 26

mons to | Haat receptor ty nat An
ate [Pana

el controlled by the NMDA receptor permits both sodium and ale
enter the cel, The influx ofboth of these ion causes a depolarization, of cours, but
ham (Ca) in especially important. Calcium serves a cc
activan tarios enzymes within

‘roca proper the | Seats eset
‘snapse that prosde one of the building blocks ofa newly formed memory. These | Paare trat

130. DER cnarren «rtm,
Figure En fle of

remate Maio ofan NMDA receto, with binding ses.

Caoum

APS Cameo phone
FoF noi ar ut
Pers
Ie à ga ns
De GAD oes
Bs the te a GA
mmol mus mn À
aie ewe)
‘erect rap lore
ÓN

more detail
‘Phoxphonopentancat) blocks e latamat bin
ne NMDA receptor and impair mapa plastic ad
etai forms of learning

ents à schematic diagram of a

its binding sites. Obrionst ge
‘mate binds with one ofthese site, oF we would not
‘glutamate receptor However, glutamate y itself canot
‘open the calcium channel, For that to happen, a mole
feof gine must be attached to the glycine binding
Sie, located on the outside ofthe receptor (We do not yet
ncersand why glcine—which alo serves as an i
tory neurotransmiter in some parts of the central
wow semis required for this ion channel to

open.) (See Figure 1)

‘Onc ofthe ax binding ites on the NMDA receptor is
sense 1 alcohol. ac a we will seein Chapter I,
searchers ice that this binding sit responsible for
the dangerous convulsions tha ean be caused by sudden
ithdraval fom hea longterm alcohol abuse, Another
Binding ste is senshe 10 a hallicnogenie drug. PCP

ngel dst”). POP serves

a an indirect antagonist when I attaches to is binding site calcium fons can
pas through the ion channel PCP i a snthetic drug and is not produced by th
rain. Thus ot he natural ian of he PCP binding se, What that gan
sind hat ute functions i serves are not yet kno
pes A yon already knows NMDA, AMPA,
plors named alter them.

aa

GABA (gamma-aminobugricacid) is produced from glutamic acid by the action
‘ofan enzyme (glutamicacid carbone, or GAD) that rem a arbox group.
Treat GAD an hs ve sis GABA
20 Figure 4), GABA isan inhibitory n itera
‘idesread isrbuio troughout e brain and spinal cord Teo GBA rec
ave been identified: GABA, and GABA, The GABA, receptor i ionotropic an
«controls a chloride channel: the GABA, receptor is metabotropic and controls
potas channel

À sou know; neurons in the brain are greatly interconnected, Without the a
divi ol inhibitory mass these interconnections would make the brain stable.
‘That à through excitatory smapses ncurons would excite their neighbors, which
would then ect irneighbon, which would then excite the originally ative net
Tons and so on, unl most ofthe neurons in the brain would be firing uncontrol
Hab Infact is cent ds sometimes occu, and we refer to tasa ut. (El
isa neurological disorder characterized by the presence of seizures) Normal a
inhibitory influence is supplied by GABA secreting neurons which are presen
lange numbers in the brain. Son ators believe that one of the causes of
<pilepy san abnormality in the biochemistry of GABsccreting neurons or
GABA receptors

Like NMDA receptors, GABA, receptors are complex they contain a east ive
ler binding sites, The primary binding site, of course, for GABA. The drug
‘muscimol (derived rom the ACI agonist, muscarine) serves as dire agonist or
his ste (step 6 of Figure 4.9, Another drug, Biuuline, block this GABA binding

131. site, serving asa direc antagoni (step 7 of Figure 4.)

A second te on the GABA receptor binds with class of

Asche lutin fa GABA, receptor, with ts big te

ys calle the benzodiazepines. These
drugs include diazepam (Valium) and chlordiavepoxide agas Shot
(Librium), which are used 10 reduce anxiety. promote Peron carnal

sleep, reduce seizure activi, and produce museo ela:
on. The thi site bind with barbiturates. The fourth
‘rious steroids, including some steroids
uce general anesthesia The filth site binds
poison found in an East
aio, alcohol binds with one of these stes—prot
Binding e. (See Figure 412)
at bind to the ter site, and
benzodiazepines al promote the acti ofthe GABA te
ceptor: thus, all these drugs serve as indirect agonists.
nxioyties or
nxietsliwolving” drugs, They are often used to treat
people with anxiety dorer. In addition, some benzo-
isrpines serve a effective sleep medications, and ah
er are used to treat some types ol se
In low doses barbiturates have
progressively higher dose they produce dif
ing and talking, unconsciousness, co
‘hough veterinarians sometimes use barbiturates o produce anesthesia for surgery,
the therapeutic index he ratio between a dose that produces anesthesia and one
that canes fatal depression ofthe respiratory centrsol the brains small Asa con
sequence, thew drugs are rarely sed by themselves to produce surgical anesthesia
in humans.
Picrotoxin has effects opposite o those of benzodiazepi
ints the activity of the GABA, receptor, tu
High enough doses this an
Various steroid hormones are normally produced in the body, and some hor
mones related 10 progesterone (the principal pregnancy hormone) act on the
‘Steroid binding sico e GABA, receptor, producing ascdathe effect. However the
brain does not produce Valium, barbiturates or picrotonin, What are the natura lig:
nds for these binding sts? So far, most research has concentrate on the benzo-
“azepine binding st, These binding sites are more complex than the others They
‘can be activated by drugs such as the benzodiazepines, which promote the activity
‘of the receptor and Ihn serve as indirect agonints, They can alo be activated by
her drugs that have the opposite effect—that inhibit the activi o the receptor
thus servings indirect antagonist. Presumabh; dhe bran produces natural ligando
that act as indirect agonss or antagonists at the benzodianepine binding e, but o.
fa, such a chemical has not been tented
Wh: GABA, receptor? This metabotropic receptor, coupled 10 a G
protein, serves as both a postymaptie receptor and a presynaptic autoreceptor. A

CADA goin, baclofen, serves as a muscle relaxant. Another drug. COP SEAS, | besotee de er
server an antagonist. The activation of GABA, receptors opens pou cha | Ya Actos yema
ch producing hyperpolarizing inhibitory posmapt potential en

ami ange coh) an
een

ne ah sr An o

no acid peine appears to be the inhibitory neurotransmiter in the
spinal cord and Tomer portion of the brain Lite is known abouts biosmthetc | Ardem Ph Aramco
pathway: dee ae several posible routes, but not enough fsknewm to decide how | cuanto reine a
neurons produce glcine. The bacteria that cause tetanus (lock) release a | Sem asp os

132. ET carrer «:mrsteracony ron ablorgmancomvcronse

tyne rt men A dt
Mn me oye ep
endogenous opa edge
son pe op Acs le
«total kato) One

es po

chemical that prevents the release ofgheine (and GABA aswell) the removal of
inhibitory effect of dese synapses caes muscles to contract conti

he phe receptor is jomouopie, and it controls a chloride channel, T
hen it isan. produces inhibitory postsynaptic potentials The drug stryehnine,
An alkaloic found inthe seeds of he Siryhnos mus vomica, à ce oud in Inia
Servesasa glycine antagonist Surychnineisvery toxic, and even relatively sll doses
«cause convulsions and death. No drugs have yet een found that serve as specie
eine agonists

Peptides

Recent studies have discovered thatthe neurons of
dense a

central nervous sem re
ge variety of peptides. Peptides const of uo oF more amino acid linked
together by peptide bonds. AN dhe peptides that have been studied so far ate pro-
duccd from precursor molecules These precunors are large polpeptides that are
broken into pieces by special enzymes À n anufactures both dhe pohpep-
tides and the enzyme faces The a
propriate sections are retained Because 1

sisi of pe cas

Peptides are release from al parts of the terminal button, not us from the ac
tive zone; thus, only a portion ofthe molecules are released into the saptic cle
The res presumably act on receptors belonging to other cell in he vicinity. Once
released peptides are destroned by enzymes There is no mechan or reuptake
and reoyeling of peptides

boy neurons. Although most peptides ap-
pear to serve as neuromodulators, some at as neurotrananiters,One ofthe bet
endogenous opioids. (ndogenaus means produced
um.) Several years ago became cleat that op
ates (drugs such as opium, morphine, and heroin) reduce pain because they have
direc effects on the brain, (Please note thatthe term opiid refers o endogenous
‘chemicals and opiateefert drugs) Pert, Snowman, and Snyder (1974) dsconered
that neurons in localized region ofthe brain contain specialized receptors hat rc
spond to opiates Then, soon ater the discovery ofthe opiate receptor, other
Foscientss disconeved the natural ligands for these receptors. (Terenis and
Wablstrm, 1975; Hughes etal, 1975). which they called enkephalin (rom the
Greek word enkrphaln, “in the head”). We non know that the enkephalin are only
two members of family of endogenous opioid, all of which ae suhesized from
‘ome of thee large peptides that serve as precursors In addition, we know that there
are atlas three efferent pes of opiate receptors (mn), 5 (dela), and x (kappa)
Scverl diferent neural systems are activated when opiate receptors are sin
lated One pe produces analgesia, another inhibits speci pica defensive responses
sich as ling and hiding, al another simulates a stem of newons vole in rc
inforcement reward") The las elle explains hy opiates ate often abused, The st
tuations tha cause neurons o secrete endogenous opioid re dace in Chapter 7,
and the br iss of opiate addiction are discussed in Chapt
Soar, pharmacologias have developed only wo ypesof drugs
communication by means of opioids: direc agoniss and antagonis Many sae
‘opiates including heroin (ditydromorphine) and Percodan evorphanol) have
of Figure). Several op
we 4), One of them,
raloxone, is wc clinical o reverse opiate intoxication. This drug has sve the
liver of many drug abusers who would otherwise have diel of a overdone of her
‘Several peptide hormones are alo fond inthe brain, where they serve a new.
ripheral and central peptides perform related
nero 1 hormone angiotensin acts

wech 16.

act neural

romodulaors In some caes the

133. dirty on the kidney and blood vesch o produce effects
Aa help the body cope with he loss of ai, and inside the

‘neurotransmitter perform similar functions, including the
Acikation of neural crits produce thir.
Many peptides produced
Dehaviral effects, which will
hapien.

Lipids
dan vile or bern ne aco
to be embase ac! nds for the veep at
ie espmable forthe polo effec ofthat in
Fri cua drocamtinal the acne ingreion of mar
exons of te bran Se ar 13)

THC prodaces aula end sion, stiles up:
pes res rs ced by drugs wed tat cc
ther han
sudor pren
aka, 200), Beane eal (189)
recerca die mine that
pe
deed and rendait

Ñ

ipids can serve to transmit

Atleast two the

HG iterferes with concentration and

ele and is mot stored in snap

(behavior effects ol THC were not seen in youn

imnanure be
elects, Ont
and vomiting eased by chemotherapy for cancer young e
a, 1905). The drug succesfully blocked he side

‘tt producing the pryhotropc effect that
vestigator were able o administer very
have been trate

ached atlas some of the eur

ass of this observation, they

Nucleosides

ther of the effects of THC i interference with the fe

HG produces in adults.
ones of THC that alts wondd not

ts soliton making raie lige
forthe ceptor The receptor ae dates by dark ern
(Autorograpy einen Chapter 5) (rst = ban
{anos = amores nui CP = au palio
hop = pecar Sh sant na)

motor disorders. On

nemory altes visual and

and disorı perceptions ofthe passage of time (Kunos and

sual liga forthe THC

y named anandamide, from the Sanskrit word

bls.” Anandamide seems to be synthesized on demand hat ts pro-
vesicles

oning of SHT, re
thin, THE serves

mete (antvomiting) drug, ride and Mechoulam (1996) diconered that
ice, whieh suggested that the

mechanisms respon

cl using THC 10 con

for these

A nucleoside is compound that consists of a sugar molecule bound with a pune

or rt
nd adenine), serves asa neuromodalator in the bran
Adenosine s known tobe released, apparently by

are short of fuel or ange
helping ring more of dhe needed substances 1
receptors. Adenine receptor are coupled 10 G protcins, and

potassium channel, producing in
‘ne is present inal els investigators have not et secede

toms that release this chemical aa neuromodulator Thus circuits of sdenosinergic

herons have not ye been Mente.

nkline base. One of these compounds, adenosine (a combina

hal cells aswell as neurons,

sc of adenine activ

‘on nearby blood vessel and cases them to dilate, increasing the Nw of blood
region. Adenosine

a neuromodator, through its action on at east three different pes of adenosine

bitoy postsmapic potentials. Becas adeno-

Libose
e | feos ated th se
my | aire meet ol maar

denia den A

so acts a
reffectistoopen

134. BEI carrer 4: ryrctvrecany ov ablongman cometen

callen Ag tat es
ivi onde NO) As
‘hes yee en sy
A]
ne ra ee

Because adenosine receptors suppress neural activity adenosine and other
axlenosine receptor agonists have generally inhibitory elfect om behavior. In act, as
else in Chapter, some investigator lieve that aleosine receptors may be
Jmol inthe control sleep. Avery common drug. caffeine, Docks denen re
ceptors (step 7 of Figure 4.4) and hence produces excitatory effect. Caffeine ls.
Fieras alkaloi found in coffee, tea, cocoa beans, and other plans In much
ofthe world a majority of the adult population ingests caffeine exerydy-—fo
‘ates without apparent

Soluble Gases

arbon monoxide—to communicate wih one mother: Onc of
these rc oxide (NO), has received the mos attention. Nic oxide (nos o be con
Fuse with ios oxide, or ging is) ia souble gas that produced by dhe a
tity ofan ene found in certain neurons Rescarher have found that NO I ud
asa messenger in many parts ofthe bod for example, ii inohed in the control
the muscesin the al ofthe intestines, e ias Blood wees in regions of he br
thar become metabolicall acte and italia the changes in blood vesck that pro
‘duce penile erections (Caleta and Ketan, HH) À we vil sec
ako pla role nthe establishment of neural changes hat reproduced by lear
Al of the neurotransters and neuromodulators discussed so ar (with the ex
‘ception of anandamide and perhapsadenosine) ate tored in synaptic vesclesand te.
leased by terminal buttons Nüri oxide fs produced in several regions a am
cellmincluding dendeies—and released as soon sit is produced. More accurately,
it dits out of the
bound receptors but enters neighboring cells where activate an enzyme respons
ble forthe production of a second mesenger, eee GMP. Within afew seconds ol
Being produced, nitric oxide I converted into Biologically inactive compounds
‘tric oxide is produced from arginine, an amino aci, by the actration of
‘eye Known a rc oxide synthase, This enzyme canbe
‘ure 44) bya drug called ENAME (nitro -arginine methsl este).

INTERIM SUMMARY

Neurotransmitters and Neuromodulators
‘The nervous stem contains a variety of neurotransmitter, ech of which interacts wth a
specialized receptor. Those that have received the mos study ar acetylcholine and the
‘moncamines: dopamine, norepnephvne, and S-hydrosyryptamine serotonin), The syn
thesis of these neurotransmites is controled by a seres o enzymes. Several amino cis
ao serv as neurotransmitter, the mos important of which ae glutamate (glutamic a),
‘GABA, and glycine, Glutamate Serves as an excitatory neurotransmitter; the others serve as
Inmbitoryneurotranamiters

Peptide neurotrammiters const of cain of amino cis Like proteins, peptides are
‘synthesized a the nibosomes according to sequences coded for by the cromoromes. The
best not das of peptides in he nervous sytem indus the endogenous opioids whore
elects are mimicked by drug such as opium and heroin. One lipid appear to serve 389
Chemical messenger: anandamide the endogenous ligand forthe THC (marijuana) eeptor
‘Adenosine a nucleoside that has inhibitory effects on synaptic transmision i release by
‘neurons and ga cals in the brain. In addon, two soluble gases ni oxide and carbon
monride_can diffuse out of the cel which they ae produced and trigger he produc
tom ofa acond mesenger in act cl.

This chapter has mentioned many rugs and her effects. They ae summarized for your

135. Table 4.3
rage Men
ect on Smapte
Newowansmiter name of Drug Effet of Org ‘ananion
cil (AGH) Borulinum von Tock release of AGE pe
Black vider venom Simulate reise of ACH ‘Agonist
Nine Simulate nico receptors Agonist
Curare Block icone respons Atagonit
Muscarine Stimulate muscarinic receptor Agonist
Atropine Block muscarinic receptor Antagonist
Neosigmine Inhibit acenlhotinestrase Agonist
Dopamine (DA) 1DoRA Fact thesis of DA Agonist
Auer. Tab pes DA Antagonist
Reserpine Tobit orage of DA in apt ees
Corpromasine Blok D, receptor
(api) Blok D, receptor
(Gaine: mehyiphenidte Block DA reupake
Amphetamine Stimulate release of DA
Depreny Block MAO
[Norepinephrine (NE) Fire ac Inhibit ythesis of NE
Reserpine Inhibit storage o NE in sap esis
romo Block autoreceptors
esipramine Inhibit euprake of NE
MDMA, amphetamine Stimulate release of NE
Serotonin (547) OPA Innit oben of HT Antagonist
Reserpine Inhibit storage OST in apse vesicles Antagonist.
Fenuramine Simulate release HT Agonist
Floetne Inhibit euptake of SAT Agonist
isp Simulate HT, receptor Agonist
MDMA Stimulate release of HT Agonist
Gluamate AMPA Stimulate AMPA receptor Agonist
ani acd Simulate ait receptor Agonist
NMDA Stimulate NMDA receptor Agonist
as Block NMDA receptor Anagonia
Gana Abigcin bit yes of GABA, Anvagonit
Mio ‘Stimulate GABA, receptors Agonist
Bicuculine Block GABA, receptors apart
Benvodarepines Serve as indirect GABA agonist ‘Agonist
Seine Supchmine ‘Block cine receptors Antagonist
Opioids Opiates (morphine heroin, ete) Stimulate ope receptors Agonist.
Neeson ‘Block opiate receptors Antagonist
Adenorine Caine Biockadenoin recepons agent
ii oxide (NO) LNAME. Inte thes of SO ‘Antgoniat

136. BREED carrer Poumon)

or abiongmon comarionée

ILOGUE
Helpful Hints from a Tragedy
he core OM PT damages seeing binant there: ers th Pro die Ho oe
A ae ee
ee ee | exons ers me ee
Pera rr an tdt paras
pe poa rare
ere nn

{Utes of Health, nd found tat 3087
Sent publications eee to MPTP)
“The fst sep wos o find out whether
{he dr would have te same effect in
laboratory animass tha the ets of
the proces coud be studied K di.

"as li he els art el. 190
The enayme that comes MPTP into
Po" on otra an monoamine
ido (MAO which, you now
now respond for esta ex
ess amounts of monoamine presen

‘ours heh sugges that eno.
‘ental ons produced in tee oc.
‘es maybe responsible or the ran
damage (Tanner 1988; Vean eo
198) Fortune, several MAO in
bon have ben ested and approved

Langston et a. (88) fund hatijec- termina button Because parmacolo. for use in human One ol hem, de.
‘one of MPTP produced parimonun _gtshadaendydeeoped MAO mem was tested and appeared to slow
motos in squrelmonkesand ut itor, Langston aná hs caeague e- Gown te progression of newrelagcl
‘hese symptoms cad be reduced yet see whether ene of these drags Symptoms itd and Langston, 969)
{COOP therapy And jst asthe mvest- argyle) would protect squerel mon. "Ava rent of thi study many nv
‘itor hadhoped examination ofthe Kestrom the tonces of MOTP yoga are ow treating re Por
anima bras shout loss preventing RS convesion mo MPF Sons patent wth previ espect
‘et dopeminesecrtingneuronsin he Langton etal, 1984) worked when during the ery sages ofthe due.

Santa gr.

MAO was inhibited by pargyine. MPTP

More recent ste oud tat depre

tu ou that MPTP vel des net injection hada effect. 00 not pote dopamnergi neun
‘use neural damage send, the drug Trev rent made resortes mon inde (hauen et, 2000, But
iSconveredbyanenaye present in” der whether MAD NON MEN reset are tying to develop other
ac inte anther substance, MPP. AB pot agaist he degeneration rage wit mote stained negro
Thatchemialistakenupty dopamine. of dopamineseceing euronsin pw. netos.

PRINCIPLES OF PSYCHOPHARMACOLOGY
Phat
absorbed, i

is the process by which drugs are
ued within the bods, metabolize

and exercted.
Drugs can ata several different ies have several
diferent effects. The eflecvenes ofa de se mag
nitude ofthe effects ofa gen quantity ofthe drug.
sey

duces tolera

drug discon
ration ofa drug causes sensation,
Rescarchers must control for placebo effets in Both
humans an

ued, Sometimes repeated

laboratory animals

PHARMACOLOGY OF SYNAPSES
Each of the steps involved in map transmission
«an be interfered with by drugs, and some can be a
lied, These steps include synthesis of
transmiter, Morage in synaptic vesicles, reas
activation of postmaptic and presynaptic receptors,

14 termination of postsynaptic potential throug
Teaphake or enzymatie descivaio.

NEUROTRANSMITTERS AND
NEUROMODULATORS

Neurons use a variety of chemicals as neurotransmit
(ers, including aceitehotine

(dopamine, norepinephrine, and SAT). the amin
acids (glatamie acid, GABA, and glycine). various
Pepe pids maclosides, and soluble gates.

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138. CHAPTER OUTLINE

Experimental Ablation

Methods and Strategies . :
of Research 5

Recording and
Stimulating Neural
Ay

Neurochemical

Genetic Methods

1. Discuss the research method of experimental ablation: the rationale, the
valuation of behavioral effects resulting from brain damage, andthe production
of bain lesions,

Describe stereotai surgen

Describe research methods for preserving sectioning, and staining the brain and

for studying its pats and interconnections.

A. Describe research methods for racing eferent and afferent axons and for
tung the Iving human rain,

Describe how the neural activity ofthe brain fs messured and recorded, both

electrica and chemically

Describe how neural activity in the brain is stimulated, both electrically and

Describe research methods for locating particular neurochemical, the neurons

thot produce them andthe receptors that respond to them.

8. Discuss research techniques to identity genetic factors that may affect the
development of the nervous system and influence behavior

>

139. PROLOC

Heart Repaired, Brain Damaged

AN er fe, Mes hd ben ace-She her hr muse had inrease.Mer od so hat ha surgeon could ut out
had never been partly att but dogged coronary arteries imply could the desd section ol he arteries and

she ander usan often went hing notkeepup withthe demand and he lately sein the replacements
Severa days later, OF. vied Mrs.

camping wth tiren when acumulan of metabol products

they were youn, and they contin to an inem pin Her pidan cau._H.Inhe host oom. “How ae you

hike and ge o ide ries ater ter one he to rod unes ener fling M HO”
“Ten feng ve she io, bt
having woubl th my vison Evan

lien let home Her ustand ded tonand presio itopierne
‘than she wor 60 and eventhough she Tablet place under er ongu ia

0 lnge rod her bce she enjoyed the tak occured. {hing loos 0 contig, an fel i

Gerdnng and tag sound the Mr H-sopped working inher gar- rime lan

poor with her fe dentuteontincedtowalkaroundthe "Dont wory he catia “RS normal
A en ea later Mes as digr neighborhood with her Mende Then to felcanui after sch seis

ing inher garden when asudden pa one evening ile dimbng the ist surgery Your tess look fie ond we

‘roped her dest she fl sa hand purent or bed, she fe another at. dont pee a recuento your

re sauce her heat She gasped ack per hear. With icy. she angina You should be god or many
and droped her spa. The pain crept made er way to er otoom cabinet, yeas” He lashed a bread smile ser

omar ere nouer and then tav- Ware she fund her roger anette room.
But Mr Hsu problems and her

‘Seddon herlet arm. The seston abe, Fumbing with the hidproof

Vas trio: se was sure hase wos ap. Se eracteda abet and place confusion didnot get better. though

having a het ttc and as going to under her tongue, ASthe abet the sugeons ots nat a ces
But aera few minutes te pon oh and the nitrogen etered fu outome, her amy phpan sa
‘meted any and he walkedsowty Parodias, she fe regente war wong and aed De
ook toherhowse Inherehestoosen ands stumbled o), a nerosyhoiogi, to waste her
er phpian examined her and per herbed De report confamed the pias
formed some tn aná aer toi he ‘Over thenetyarthefrequengy ess Me had Balin same She
atihe had nathad a her ata Her animent of Mis Matin couidsti se, but he oul not cont
pain us hat of angina pctv cused case. Final. the spect o whom Mer ee movements The word conse
Byinsufiint Now of bleed tothe the sian padres her recom he because she sow ony Meeting og.
eat Some of her coronary arteries mended that she coir having à IE mentary images She CU o longer
ad become partly bsrcteawin rary artery bypass performed She read: read, and she ould no longer oct and
ercer plaue—<holesera ‘ly agreed. The surgeon Dr. replaced grap objectsn rom of her short. er
Centaning depot ante walls ofthe Eu fa coronary arte ithe viion wat aiment les Her ear
od vena, Mer frs er garden on foin the had rem rom ne, but she woud henceforth to
ad increased her here rate andes” herleg Dring the procedure amar. fein anung home where others

Consequence, the metal acy of Galet tk over the pumping af her caudate for

he pho o eto nhs foro ces many di
SS fis nt in, nomme Be oh
drag and Hisolgh Puring a tear projet a bei
Swi he ange an Inns of he mets te employ See
im crepes ang ion ne Tc nto a ed
mero de ecto we high weer Ave oc best mains
Shut pili) ober art made ht by any Ge pren Ou ya
ga rar a crac uo comparen ls Ga oppo
ble sl cn mea
An command beeing arc of reach med I male ve
evap I mer premeda alo thon sourate slg os
me y o er seas sent one mes or nd

1

140. CHAPTER 5: Methods an States of Resch sr ablongman com/earbonte

semen Dern
rl rm, ne nn
a o ga e pore
Bene engen pesas
son study sanyo
encore 909
fou A an en poses
ci cin ola er

commonly used procedures, orgunized around few problems that researchers have
studied. This way, should he easier sc the peso information provided by var
ious rescarch methods ando understand their advantages and diadkantages. I will
“lso permit me to describe the strategies that researchers employ as they follow up
the ress of one experiment by designing and executing another on

‘One of the most important research methods used to investigate brain fune
volves destroying part of the brain and evaluating the animal's subsequent behavior
“This method is called experimental ablation (rom the Latin word alas a “car
ing away). In most cases experimental ablation does not involve the removal of
brain tine: instead, the researcher destroy some se and leaves tn place. Es
perimental ablation isthe oldest method used in neuroscience and i remains one
‘ofthe most important ones today

Evaluating the Behavioral Effects
of Brain Damage

injury anda researcher who destroys par ofthe brain wl
Fefersto the damage asa brain lesion. Experiments in which part of the brain isda
aged and the animals behavior is subsequently observed ate called lesion stdin,
‘The rationale for lesion studies that he function fam area ofthe brain can be in.
ferred from the behaviors thatthe animal can no longer perform after the area
«damaged, For example, after part of the brain is destroyed, an animal can no
longer perform asks that require vision, we can conclude that the animal blind
and that the damaged area plays some role in vision,

‘We mus be very careful in interpreting the elects of brain lesions For exa
ple, how do we ascertain that the lesioned animal blind? Docs bump Into objects,
eal tor à maze toward a ight that signals the location of food, or o.
longer constrict objects because of
deficits in motor coordination, it could have lst is appetite for fod (and ths its
‘motivation to run though the maze), or it could see quit wel but could have lost
is visual reflexes, Researchers can often b that the
albino rat was blind. (ist) Think about it How would you test wheter a rat can
See? Remember that rats have vibrisse (whiskers) that can be used to detect a wall
before bumping into itor the edge o table before walking oft. They an also
hci way around a room by folowing odor tri

shat ean we lear from leon studied Our goa ist discoer what fu
red by diferent regions ofthe brain and then vo understand how these
funcionsare combined vo acconplsh parti

behavior. The disinction between
‘rain function and deko a important où

funcions, not behaviors. No one brain region or neural circuit soley respon
fora behavior; ach region performs funcion or set of actions) that con
1 performance ofthe behavior. For exan

required fr con

Circuit within the br

are required for performing a particular behavior ine what circulo

re responsible Fr each of

141. Experimenta oon 125
Producing Brain Lesions «GDA

How co we produce brain lesions? I i cas o destroy parts of the Ra uen} aon. he aro poi to wey
train immediately beneath the kl we ns dh animal cut leer nosed pig ade ean

ois skal and ct though the dura gag nt dpc rasta
mo er: Then we ‘ecole how mie made oe pta
tie o aire bran tame To accompa ‘Botner roman, eso ae)
place gls pete othe surface of heb p

GER 2

tise with a vacuum pump attached tothe pipe
More often, we want to destroy regions that are h

ain lesions a subeortica regions (regions

cortex) are usual produced by passing elect

a current through stainless see ire tas coat with an inst

Tang varnish except for the very ip, We guide the wire sercotaicall

locaton, (Stercoasie surgery

on lesion making

device, which prod

ec produces heat that il cell in the region surro
ing the ip of de electrode. (See igue 3.)
cd by these mea

ncurons that passthrough the region. A more selective me
producing brain lesions employs an excitatory am
Iii aci wi Kills neuron by silat
sions produ

but spares axons that belong to.
Figure 5.2) This selectivity permi
havioral effects destroging a particular
neurons located there or by the destruction of axons

coton ean Scion trough nema! ippocampas aa at brain (0 lesion produced
Ex hu of an act amino sc arto fe pan Aron sde mar the ends
‘tthe region pic oro ave Ben eros.

142. MER carrer : rod snd sates Rasch wor. alongman comiationse

produc à an eon exe
{err oe hat tay ce
stereta surgery ee oh
Empire
ne Mentone

loan a target or a code placement Top:

Dol ew atom MG vi

Not that when we produce subcortical ions by passing RE cure:
an electrode or ifising a chemical through a canna; we aly cas
damage wo the brain, When we pass an électrode or a cal through the brain to
get our target, we inevitably cause a small amount of damage even before turing,
fn the lesion maker or starting the infusion. Therefore, we cannot simply compare
1c behavior of brain-esioned animals with that of unoperaed contol animals the
incidental damage w the brain regions above the lesion may actual e responsible
For some ofthe behavioral deficit we ace, What we doi operate on a group of an
‘mals an produce sham lesions. To do wo, we anesthtize each animal put ti the
stereotaxic apparatus (described eo). cu open the scalp. dil the holes insert
the electrode or cannula, and lower eto the proper depth In other words, we do
ng we would do to produce the lesion except turn on the lesion maker or
ah server ava control groups ifthe behavior of
mals with brain lesions different rom that ofthe sham-operated control
al, we can conclue that he lesions caused the behavioral deficits. (As you ean
sce, sham lesion serves the same purpose asa placebo does in à pharmacology
studs)
Most fe time, investigators produce permanent brain lesions, but sometimes
is advantageous o disrupt the aci ofa particular region of the brain ten
porary. The eases way todo so ito inject local anesthetic ora drug called mus
‘imainto the appropriate part ofthe bran, The anesthetic blocks action potentials
in axoms from entering or leaving that region, dns effectively producing a tempo
rary lesion (wally called naerbrain lesion) Muscimol, a drug that simulates
GABA receptors, inathates a region ofthe brain by ibiiing the neurons located
‘there. (Vou il reall that GABA Ss he mos important inhibitory
inthe brain)

through
racional

Stereotaxic Surgery

So how do we get the tip ofan electrode or canmula o a precise

location in the depths ofan animals bran? The answer itereo-

tae surgery. Sermiani literally means “wld arrangemen

more special, refers o the ability to locate objects in pace

A mac pparatus contains a holder that Fixes the animal"

thea in astandard postion and carrer that monesan

‘ora cannula through measured dst

space. However o perform stereo
ny à rta as

ces in all res axes of
de surgery, one mus fist

The Stereotaxic Atlas

No two brains of animal of a given species are completely
identical but there is enough similarity among individuals o pre
ie the location of articular brain structures relative to external
Features of he head For instance, a subcortical nucleus of rat
right be so many milimeters ventral, anterior, and lateral to a
point formed by the junction of several bones of thes Figure
53 shows two view of ara skull a draning of de dorsal surface
“and, beneath it mida view. (See Figure 5.3.) The kal is
‘compened of several hones that grow together and form suture
(Game). The heads of newborn babies contain a soft pot at the
junction of the coronal and sata sutures called the fontanel
‘Once this gap closes, he junction à called bregma, from the

“front of head. We can fel bro

143. he animal’ skulls oriented as shown in the istration, a pa
brain found in a fait constant position, relative to bregma.
A sereotaxi as contains photographie or drawings that correspond to frontal
sections taken at various distance rostral and caudal o bregma. For example, the page
contain a brain sucre
ed 10 place he ip of wire in this
€ ihe for), we would have to dr a hole through the sal immediately
Above it (See Figure 3.4) Each page of the stereotaxic alas isabel according o
tance ofthe section anterior or posterior to bregma. The grid on each page indie
‘ites istances of bain structures entr o the top ofthe skal and lateral tothe mid
Tine. To place the ip ofa wire inthe fornix, we would dill a hole above the target and.
then lower the electrode through the hole
tive to the skal height at regia, (See Figures 53 and 5.
structure (which we cannot sce in our animal) on one ofthe pages ofa tereotaic at
las ne ca determine de rue aan ele

cular region ofthe

The Stereotaxic Apparatus

A sereotasie apparatus operates 0
Acad holder, which maintains the anima
for the electrode and calibrated mechs
measured distance along the three axes anterior-posterior, doral-venttal, and
Yateral=medial. Figure 5.5 late a sereotase apparatus designed for small an
mal; various head holders can be used 10.0 device for such diverse species
ax at, hice, hamsters, pigeons, and tare. (See Figure 3.5)

simple principles, The device includes a
the proper on, a holder
that moves the electrode holder in

retains A cocon
mage of men fe an
a ar ma mi ma
rer nr
rot apart cece

sample page rom serai aia of the rat rai. The age A seront appara fr prtorming brain rer on at.

{tne fon aindatedin red Label ave Ben remove forte
‘ste of can

Toe te

sing
ES

144. due of Rs ‘worvablongman con/cronte

Once me obtain the coordinates rom a stereotatic a
Jas, we anesthetze the animal, place iin the apparatus,
and ut the scalp open. We locate bregma, dal the ap-
propriate numbers on the Mercotaic apparatus, dil a
hole through the skull, and lower the device ino the
Brain bythe correct amount. Now he tip ofthe canoa
‘electrode ls where we want to be, and we are ready to
produce the lesion.

‘OF course, sereotaie surgery may be used for pur
poses other than lesion production. Wires placed in the
brain may be used to stimulate neurons aswell as destroy
them and drugs can be injected that stimulate neurons
or block specific receptors, We can atach cannulas or
‘sites permanently by following a procedure that will be
described later in this chapter In leases, once surgery
is complet, the wound i sewn together and the animal
is taken out of the stereo apparus and allowed tore

cover (rom the anesthetic

"Stereos apparatuses are alo made for humans, by
the way. Sometimesa neurosurgeon produces subcortical
Tesions tor example, to reduce the symptoms of Parkin

ns dicasc Usually the srgeon uses multiple landmarks and veis the location
ther device) serca into the brain by taking MRI scans before pro-
‘ducing brain lesion, (See Figure 5.6)

Histological Methods

Aer producing abran lesion and observing its effects on an animals behavior, we

‘must slice and san the brain so that we can observe i under the microscope and

sce te location ofthe lesion. Brain lesions often miss the mark, so we have to verify
the precise location ofthe brain damage after testing the animal behasiorall Todo
o, we mus fix, slice, tain, and examine the brain, Together, thee procedures are
referred tos holga! methods. (The prefix hi refers to body tise)

Fixation and Sectioning
Ive

ope to study he sue in the Form ha atthe me ofthe organism's
death, we mist destroy the autoltie enzymes (auohte means “selfdisolving’y
‘hich wil otherwise um the issue into mush, The ie must

GUISA e e peered o pes compo y ca
‘molds. To achieve both ofthese objective, we place the neural

tise ina faire, The most commonly used fixative is formas
finan aqueous solution of Formaldehyd, agus. Forman has

stoi, hard the very soft and fragile brain, and lls any

‘Once the brain has ben fixed we must lc tino thin se
tail Stings done wth amierotome (tral "hat which ics
small. (See Figur 5.7) Slices prepared for examination under
alight microscope are cal 10 to 80 jim in thickness those

prepared forthe electron microscope ae generally cut at es
han am. (A um. or mime is onemillonth of meter, or
oncahousandih ofa millimeter) For some reason, slices of bain

145. tie ino various chem
mal amc

thin gas coverslip over the sections. The
prion: Animacion 3, Milage! Methods, shows

Staining

sue under a microscope, you
(routines of some large celular masses and the more prom
ne detail would be revealed. Fr this reason the

dy of microscopic neuroanatomy requires special histologieal stains. Researchers
iy specific substances within and o

of brain lesion, we will use one ofthe sim

side of ells For verifying the loca
pleat acelhbody stain

nthe tate nineteenth cen
that dye Rosen as meth

Franz Nil, a German neurologist, discovered
lue would san the cel bodies of brain tie
material that takes up the dye, known asthe Mis susan consist of RNA, DNA,
“and associated proteins locate in the nucleus and scattered, in the form of granules,
inthe topa. Many dyes besides methylene blue can be wed to tin cell bodies
Found in slices of the rain, tthe most frequent sed sere ole. cident;
the dyes were not developed special for histological purposes ut were original
Formulated for use in dyeing cloth,

"The discovery of el sans made it posible to identify nuclear masses in
rain, Figure 5 shows a frontal section oa cat brain stained with ere volt
‘Note hat you can observe ber bundles thee ügher appearance; the do not take
the sai. (See Figure 5.8) The stain isnot selective for neural ell bodies al cells
Are sained, neurons and ghia alike. It sup tothe imestgaor to determine which i
ich ze, shape, and location,

Electron Microscopy

icroscope is limite in it bility o resolve extremely small details.
of ight cf, magnification of more han approximately 1500

times does not add any deal, To sce such small anatomical stares as synaptic

frontal scion oat ban, aired th rey vii cel

op now coy Noy Coan

Espert ation ATC

pointent
ideo demonsrain te
Preparation of bain tue or

"maten under moro

pates

formal fr in) Tau
tan et om ou
Se orme de
cota myo ae) An
‘eso ic

146. rope ae nd
nds rc pont cu region o

ons nan aan emia buon,

| seaming con miese

ors must use an electron mi
‘roscope. A beam o electrons spaced through the ise o be examined
À shadow ofthe sue is then cas ont a sheet of photographic im, which
isexponed bythe electrons. Electron photomierographs produced in this
vay can provide information about structural details on the order ofa ew
(See Figure 59)
A scanning electron microscope provides ls magni dad trans
ion electron microscope, which transmits the electron beam through the tise
However shows objects in three dimensions. The microscope scans the tase with à
‘moring beam of electrons. The information received from the reflection ofthe beam
‘ned to produce a remarkably detailed ecclimensional view (See Figure 5.0.)

veces and details of cell omganells ive

Tracing Neural Connections

Les suppose that we were interested in discover
‚ponsble frre

‘of sexual be js On the bass ofsome hi
reports of experiments by other researchers published in scientific journals, we per
Formed stereotaxic surgery on two groups of female rts. We made a lesion in the
ventromedial nucleus of the hypothalans (VMH) of the rt in the experimental
‘group and performed sham surgery on the rts in the contol group. After à few
das recovery we placed the animals (individual of course) with male rats. Th fe.
male in the control group responded positively to the mas’ atte

they en
‘kage in courting behavior followed by copulation. However the females withthe
VME lesions rejected the males attention and refused o copulate with them, We
«confirmed with histology that the VMH was indeed deatroved in the brains of theex
perimental animals, (One experimental rat did copulate, but we discovered la

har the Te animal so we discarded the data

that subject)

oplay
role in functions required for copulatory behavior in females. (By the way, uns

147. ‘out that these lesions do not a
tales) So where do we go rom here? What ithe next step? la
Fact, here are many questions that we could pursue. One ques.
tion concerns the system of bran structures

Female copulatory behavior, Certain, the VME docs not stand emi
alone; receives Input from other structures and sende out

nts o sl others. Copulation requires integration of val,
tactile, and olfactory perceptions and organization of patterns
‘of movements in response to those of the partner. In dition,
the entire network requires acthation by the appropriate sex
hormones What is the precise role ofthe VMH in this comple
cited syste?

Tefore we can hope to answer tl
more about the connections of the VMH withthe rst of
rain, What structures send their axons 10 the VMH, and to
shat structures docs he VM in tar, send ts axons? Once we
know what she connections are, we can investigate the role of

‘the nature of hei interactions. (See Figure 5.11.)
How do we investigate the connections of the VMI? The question cannot be an
red hy means of histological procedures that san all body
Stains. If we look closely a a bra that has been prepared by these meas, we sce

Bee
not affect behavior dire Neurons

rectly connected to muscles, they ca
fe VMH must send axons o parts of the
brain that contain neurons hat are responsible For muscular monements The pa
ay probably not direc; more likey neuronsin the VMH affect neurons in other
Structures, which influence those in yet other sructures unl, eventual the ap
propriate motor neurone are stimulated. To discover this stem, we want tobe able
Ko denise paths followed by axons leaving the VMEL In other words, we want 10
trace the fren ns tis structure.
‘We wil san anterograde labeling method to trace these axons. (Arge
"moving forward”) Anterograde labeling methods employ chemical that are
by dendrites o ell bodies and are then transported through he axons to.
vial buttons.
‘Over the ycasncurenciemiss have developed several different methods for tree
‘thay followed by efferent axons. À recent developed method is re
air mes, so this what we wile, Cell biologists have discovered that a
Family o proteins produced by plans bind with specific complex molecules present
in cells of he immune system, These proteins, called tin, have aso Found une
tracing neural palhways A particular lectin produced by the Kidney bean, PAL.
(phases vulgaris ogg, if you realy ant 10 know) i used to wey
ferent axon
To disconer the destination ofthe efferent axons of neurons located within the
MH we inject a minute quantity of PHAL in cleus. (We use a sercotaxic
110 do o, ul coune:) The molecules of PHAL are taken up by dendrites
ough the soma o the axon, where they travel by means of

‘he

notecules of HAL: dendries, so
= Then we kill the animal, slice the bra
‘microscope slides. A special immunalaiemial mu

se {Once we know that à particular brain region is involved in.
À partit in regen and mt po

anterograde Let method
nn ons Ansage
min manie
fem te bos nd wah on
pere

148. MED cose 5: cs ns ste of auch woeablongman conan

Terra for he we of PAL ce teen nom.

PHL is mena

Steven ara an

Immuncenodremial method | make the molecules of PHAM. ssl, and the slides are examined under a micro-
Arno manos ur | Scope. (See Alpen 32)

pre Immunocytochemicl methods take advantage of the inmune reaction, The
Se Te, | Body’ immune stem has the ability to produce amibodiesin response o antigens
tens pees Antigns are proteins (or peptides), such a thone found on the surface of haters or

Virus. Anti, whieh are also proteins, are produced by white blood cesto de
stroy invading microorganisms. Antibodies either are sereted by white blood cells
iter eceptorsare located on

Ter bythe ite id cle
Meneses uv cea É de for producing
venom te mi te an a pi or rotin The aby
Sup by denies ead a re OB ao cach various pes of dye ler
am Baek tthe de ect wa eer chemi and ain
tha brown color Olesa Men hey go wben
theyareeapsed o ligt ofa portcularwactngi To de
termine vire the pepe of poten (eaten) slo
‘ced inthe bea mot
males The anv
Ben. When megas canines theses wa à
Soncope (ander Ii of parts msg ine
coe of unen peor dc
the raven whch ina

antigen,

andhody/dye
ich themes tothe

5.13 shows how PHAM ca be used o ent
€ brain, Mole
VMI. Two

the llena of

cule of this chen
“asar, ater

149. ih a chemical procedure that stains the sae containing molecules of PHA. a | mora aten metros A
own color. Figure 3:13 show a photomicrograph of the periaqueductal gray mat. | Pappe ros ur ues ce

ter (PAG). As yo ca sce, ths region contains on
beled by the PHAL, which proves that some of
terminate in dhe PAG, (See Figure 3.13)

à continue our study of the role of the VMH in female sexual behavior, we

ergot wo 0 A

‘would find the structures that receive information from neurons inthe VMH (such | ane
US the PAG) and see what happens when each of them i desropcd, Lets suppose | am oe
that damage 0 some of these structures also impair female sexual behavior. Wewill | gamer vis A eared
injec hese structures wth PHA and sce where Iirasons go. Exentually, we will | Emo» og hope m wd

the VMH tothe mot
isnecessry for copulatory behavior. (hi

neurons whose activity | frame Cao hh

thir rel ae presented in Chapter 9)

Tracing Afferent Axons
Tracing efferent axons from the VMH will tll us only part ofthe story about the
neural crew involved in female sexual behavior the part between dhe VMH and
1 motor neurons. What about the circuits dor the VIE Is the VMH somehow

involved in the analysis of sensory information auch a the sight, oor, or touch of
the male)? Or peraps the atinating effect ofa female's ex ho
havior at shrough the VE or through neurons whose axons fi
To discoer the pars ofthe brain that are involved inthe "upstream” components
ofthe neural circuitry, we ned to Find the inputs ofthe VME
‘ons. Todo so, we will employ retrograde labeling method.
Ramgrade means “moving backward.” Retrograde labeling methods employ
thecal that are taken up by terminal buttons and carric back through the ax.
‘ons toward the cel bodies The method for idemifing the afferen inputs 102 par
ticular region of the brain ls similar tothe ried used for eng its efferent
First we inject a small quant ofa chemical called fisorogold into the VME The
chemical taken up by terminal butions and is transported back by means of re
road axoplasmic ut
slice brain and examine the se under light of the appropriate wavelength, The

es on her be

m sapnes here

porto the cell bodies A few day later we kil the animal,

molecules of luorogold More under this ight, We die
‘over that the media amygdala is one ofthe regions hat
provides input tothe VAIN, (See Figure 5.14)

he anterograde and retrograde labeling methods

that Ihave described identify a single fink ina chain of Out tere as aden op terme batons no opi
Tar brain region, Trensnronaltacing methods identify hon ee el Doe ested the me mga.

Synaptic connections wih each other The mos effective
‘rasa weakened form of a pig herpes virus that was
original developed as vaccine. The russ injected de

and infects them, The virus spreads throughout the i
fected neurons and is eventually released, paing on the
infection to neurons with which they form smaptie con
nections. Some neurons are killed by the viru others sur
tive the infection. This method can be wed 10 trace

The longer the experimenter sait atrinecting the
virus, the larger the number of neurons that become

150. CHAPTER 5: Methods and Sates of Rech \worwablongmancon/aonte

A 5:15 ine at

ley anterograde ad retrograde labeling methods

agama tie: Ces reyonalte for female at mating postre, Aer a fer

nse sc
Li

en

animal Kill and the bra i ice im
munoeytochemical methods are used to localize
‘duced by the virus. For example, Dan

Flanagan-Cato (1999) injected pseudorabies virus in them

‘ays the rate were killed, and their brains were examined os
study indicated that u
its way up the motor nerves to the motor neurons in the
nal cord, then to the reticular formation of the medulla,
then tothe periaqueductal ray mater and finaly othe VA
“These results confirm the result of the anterograde and retro.
grade labeling methods I just described, (fected neuroms
vere found in other structures as wel, but they are not relevant
tothis discussion)

Together anterograde
including tansneuronal methode
cits of

idence of viral infection
foun

d retrograde labeling methode

able us o discover ir
connected neurons. Thus, these methods help o
us wth a “wiring diagram” ofthe brain. (See Figure
5.15) Armed with other rescarch methods (including some o.
be described ater in this chapter), we can ty to discover the
functions ofeach component ofthis ie

meer Study of the Living Human Brain

oda ar

computer tomegashy (cn
Mola e tavern
mp on da
Cta sang been
‘rooney

magne resonance maging
op
‘traf oy De ac
‘te mage bes ee
og mare Fl

state the functions of
ans For one thing, we can
compare the resultsof studies made wit different species in order to make some
Terences about the evolution of various neural stes, Even if our primary interet
isin the functions ofthe human brain, we certainly cannot ask people to submit
brain surgery forthe purposes of research, But diseases and accents do occasion

and if we know here the damage occur, we can
Studs the peoples behavior and try to make the same srt of inferences we make
With deliberately produced bran lesions in laboratory animals. The problem is,

sion

Ta past years researcher might study the behavior ofa person with bra
age and never ind out exactly where he lesion was located: The on
vasto obtain the patients brain when he or she
à microscope, But lt was often imposible 10 do so, Samen
the researcher. Sometimes the patient moked out of town, Sometimes (often, per
hap) the family refused permission for an autos; Because ofthese practical prob.
Jems, study ofthe behasoral effects of damage to specific pars of he human brain
made rather lo progress

Recent adkances in Xray techniques and computers have led o the develop:
ment of several methods for studying the anatomy ofthe Tsing brain. These ade
‘ances permit researchers to study the location and extent of brain damage wile the
patient is til ting. The ist method dl
‘ography (CT) (rom the Greek or tomes ut“
ele, usually referred to asa CT scan, works as follows The patents head is placed
ina large dough ins an Xray tube and, diet op-
poste (on the other side ofthe patient's ead), an Xray detector The Xray beamı
pases through the patient head, and the detector measures the amount ofr
dit that gets through it, The bam scans the hea rom all angles, and a com
puter translates the numbers t receives from the detector into pictures ofthe skull
and its contents (See Figure 5.16)

lod and examine slices oft

152. MID cae 5: 00 an Ste of en vv ablongman com/cronée

INTERIM SUMMARY
Experimental Ablation

The goal of research in behavioral neuroscience i o understand the brain funcions e
Que forthe performance of a patil behavior and then o lea the location of the
‘neural cuits that perform these function. Te lesion method ithe oldest one employed
in such research, and remains one ofthe mort useful. À subcortical ein made under
‘the guidance of stereotai apparatus. The cordnste ae obtained fom astereotnic a
lo, and the tp ofan electrode or anna 1 places a he target. ein made by pn
ing adi frequency curent through the electrode o nfusig an exttory amino acid
through the annul, producing an excotoxi lesion, The advantage of ecitoton lesions
ista they destvoy only neural cll bodies axons pasúng through the region ae not dar

“The location fasion mus be determined afte the animal behavior observed. The
animal isla by humane mers, and the rain s removed aná placed in a ftv such as
formalin. A microtome i used 1 ce the brain, whi is sualyfrozen to make it hard
‘enough to cu nt thin section, These setos are mounted on las sides, stained ath a
«el ody sain, and examined under a microscope,

LUght microscopes enable us ose ells and the larger organi, but an electron mi
_soicope it needed to see smal detail cha indvidal mitochondia and synaptic vei.
‘Scanning electron microscopes provide a thre-dimenionl view of tue, ut at over
magnícoton than transmision electron microcopes

he next stp in research program ota requires he invesigaor to discover th af
ferent and efferent connections of the region interest ith the est ofthe ran eMerent
‘connection (hose tat cary information rom the egin in question 1 other parts ofthe
brain) are reveals with anterograde tracing methods such s th one that uses HALL At
ferent connection (thot that bring information tothe region in question from othe parts
ofthe brain are revealed with retrograde tracing methods such asthe one that ues fu
rogotá Chains of neurons that form synapti connections are revealed by the ransneuronal
tracing method, which ues the pieudoraber vn

‘Although brain lesions are not deliberately made inthe human brain fr the purposes
research diseases and accidents can cause brain damage and ie know where the dom
ge located, we can study peoples behavior and make inferences about the location of
the neural cuts that perform relevant functions. the patent ies and he rain aa
able for examination, orinar histological methods can be used. Others, the ing bain
Can be examined with CT scanners and MI scanner

Table 5.1 summaries the research methods presented inthis section.

ithe elects of

Theft seco te anatomy o the bran
damage to particular regions This section considers a diferent approach: studying
a y recording ur tilting de acti of particular regions Bra functions
involve activity of circuit of ncurons; dus, different perceptions and behavioral re.
sponses insole different paterns of activity in the brain, Researchers have devised
methods vo record these patterns of aci or o artificially produce them

Recording Neural Activity

Axom produce ac al, and terminal buttons lic posa potentials
inthe membrane of be celle with which they form synapse, These electrical e
anges in the electrical acts ola

ca be recorded (as we sawn Chapter 2), and

153. 0 as Sing rt ty AE
Table 5.1

sch Methods: Part |

Destroy rachat pci bain Rado fequcncy eon esos abri ie near Up of.

region re
Excttoxeleson:usesexciatory Destroy only cl odes nea Up of
amino aid such aii acd ‘annul: spares axons pasing

through eon

Intuson of toca anesthetic or "Temporary nates pec brain
rmuscinol (drug at simulatesGABA region animal ean serve at own
receptor) contol

Pace let or cama in peciic_Steeotsi surgery Consult stercotnie ata for

region win bain coordinates

Find location ofeson Fix bran ice bran stain sections

enti axonsleminga parte Anterograde acing method sich as

region andthe terminal utonsof PEA

these axons

Tent locaton of neurons whose Retrograde ting method sch as
sons terminate ina parc region Moraga

‘ently cain of neurons hat are _“Transmeuronal acing method: uses Can be wed for both anterograde
interconnected aptly pudor ir and roger
Find locaton of sion in ing, Computerized tomography (CT Sos alice" rain ses Nea
uma brain scanner)
Magnetic resonance imaging (MRI Shams ce of bran: eter deta
sammen) an CT scan sea magi eld
and radio waves

particular region can be wed to deter that region pays role in a
‘ous behaviors, For example. recordings can be made during im presentation
‘cision making, or motor actives

be made dhroniall ver an extended period of time ate
animal reconen from surgery or avy, or reli shot period of tine du
hi Vis heptaneuhetized Acute recordings made white the animal s
anesthetized, are usually restricted to suis of sensory pathways, Acute recordings
Seldom involve behavioral observato the behavioral capacity of an anes:
thesized animal i limited, oy the eat

Recordings with Microelctrodes
Drags that fect sertoner qe ncuron als fet REM

step Sapos that, Knowing ia we wondered weer ai foto

te and nordrenenge neurons won vary during deren age po

fin un, we wo econ the sty of tec neuro ih microcecuodos Mic

«leidos have ary ie tp small congo record the lta co

Sit neurons This techniques wally clic glean recording (aut refers | arten wy ted

{oan Inda neuron) ET eos
Decano we wan o record the aci of single ncuron over along pero of a

mein unaneaheired animal, we want more durable electrodes We can purchase | Snarantmendng fade

ara o very invites prier peter à bundle. The viresare ined win Lars

154. MEE charter 5: tos: ana seats of Resch sv ablongman concen

GUISA 3 car that ons hc pare tae The ire are

A permanent aac of codes, witha

Connect secar

a
croencephaogran ec)

en À
Pr nd rears
fre ofthe map a o
Lo er sa ay

Sons

2 deomghone (200) ce 0
‘gion ees à pre

Fe ang ue ba
aorta A pare

‘Sen eos «pte

exible enough thar they can fallow m
ue cased by movement ofthe animal's head Ava rex, they
fre lx likely to damage the neurons whose signals they ar
‘ching. In addition, we can record the acts of see
‘dual neurons in a particular region ofthe brain.

Weimplant the electrodes in Ihe bran of animals through
sereotasie singers. We attach them 10 miniaturized electrica
Socket and bond the sockets o the animal skal using plas
tics that were originally developed for the dental profession
Then, after recovery from surgery the animal an be “plugged
in tothe recording system. Laboratory animals pay no heed to

lectial socket on ther sls and behave quite normally
(See Figure 5.19)

Researchers often attach rather complex devices to the

‘sh when they implanı microelectrodes, These devices
Jude stew mechanisms that permit the experimenter
move the clectrode-—or array of electrodes—decper
rain so that they can recor from several diferent parts othe
rain during the course of

The electrical signa dete
mal nd must be amie
work jus ike the amplien in a stereo stem, comerü
tthe brain ino stronger ones. These signals can be displayed on an exillocope
And stored in the memory a computer for analysis at a tater time.

‘What about the results of our recording fom serotonergic and noradrenergi
Aron Asyou wil ear in Chapter 9 ¡we record the activi ofthese neurons dur
ations stages of sleep, we wil ind that thir ring rates all almost o ero dur
REM sleep: This observation suggest that these neurons have a iio elec
fon REM sleep. That i, REM sleep cannot occur unt these euros stop fring

Jr observations
“by microelectrodes are quite

Recordings with Macroelectrodes.

Sometimes, we want to record the activity fa region ofthe brain ara whole, not
the acts of individual neurons located there. To do due macro.
‘lecrodes, Macrocletrodes do nor detect th
the record that are obtained wit these devices represent the postsynaptic potentials
‘of many thousunds—or millions! cells inthe area ofthe electrde. These elec
Andes can const of unaharpencd wires inserted into the Brain, crews atached o.
the shll or even metal ink attached othe human sap witha special paste that
canduet electric, Recordings taken from the scalp, especial, represent the ac
tity ofan enormous number of neurons, whose electrical signal passthrough the
‘meninges sland cal before reaching the lecrodes

‘Occasionally, newrentrgeons implant macroclecirodes direc nto the human
brain, The reason fr doing so so detect the source of abnormal electrical activity
thats giving ive to frequent seizres. Once the source i determined, the surgeon.
‘can open the skull and semene the source ofthe eures una sea ts cased
by brain damage that occurred cari in ie, Most often, the electrical acıkiy of à
human brains recorded through elecrodesatached o the scal and displayed on
an inking nella, common called Jubera

À polygrapl contains a mechanism that moves very long strip of paper pasta
series of pens. These pens are ewentally the pointers large volumeters moving up
and down in response to the electrical signal sent 1 them by the biological ample
ers Figure 3.20 illustrates record of electrical activity recorded from macroclec
trodes atached to various locations on a person's scalp. (See Figure 520) Such
records are called eletroencephalograms (EEG), or “writings ol electric fom

155. the head" They can be used o diagnose epilepsy or bra
mors orto study the tages of sleep and wahefulnes, which ae

nected with chara of electrical acti:

ss just such a procedure several year age,

os

Magnetoencephalography
As you uneoubediy know, when electrical cu

nt flows
rang condor induces magnetic fe. This means at
as action potentials pas down axons or as postsynaptic pote

‘ils pas dom dendrites or cep acronhe omatie membrane

ins detector (called supercondacting
devices or SQUID) at can detcet magic fies hat are ap-
proximately one illonth ofthe sizeof the car magnetic
cl. Magnetoencephalographyi performed with nruromagne-
someto, devices that conta an array of several SQUID, or

à computer an examine their put and calle
source of paricular signals in the brain, The neuromagne-
ometer show in Figure 5.21 contains 275 SQUID. These de.
tices can be wed clinical pl, 1 nd the sources of
Seinaresso that they canbe emoned surgical: They can alo be used in experimen
to measure regional brin ati hat accompanies he perepain of various tinal
forthe performance of arious behaviors or cognitive asks, (Ste Figure 5.21.)

ete th

Recording the Brain's Metabolic
and Synaptic Activity

Electrica signals
particular region ofthe brain increases, he meraboli rat of this region increases,
too, largely as

pump fe
boli rate canbe measured, The experimenter nf Mapa Permet shown on
dioacive Zdeoxyglucose (2DG) into the animal's ne man tothe The ese mece sec say
‘Mondstream. Because this chemical resembles glucose Seshown onthe mono Ue igh, uptime ona

{the principal food forthe brain), its taken into cells image ofthe ba dead om an sa,

Ths the most active cells which use glucose atthe high

‘est rate, will ake up the highest concentrations of ta
dioactve 2G. But unlike normal glucose, 2G cannot
be metabolized, o it stay in he cel The experimenter
then kills the animal, removes he bran, slices and pre
pars for antoadigrphy,

“Autoradiography can be translate roughly as writ
ing with one's onen radiation." Sections ofthe bain are
mounted on microscope sides, The sles are then taken
into a darkroom, where they are coated wth a pho
graphic emulsion (the substance found on photographic
fn, Several weeks later the slides, wth her coatings of
‘emulsion, ate developed jus ik photographic film. The
‘molecules of radioactive 20G show themselves as spots

the developed em
raioaciviy exposes the emulsion, ju
il de.

nly Signs neural acti: He neural activity of a

jembrane ofthe cll, Thin increased meta

of silver grains ion because the

Be Xe or ight

156. BE, ancien pose der os
énonce ase fat bathe dar pat Dom nica

ue ofatoradoprpiy to ng by carro) are nuclciol the hypothe wth an specially high metabolic a
thelocaon of ameurotamemt Chapter 9 describes these nucleate funcion (Se Figure 5.22.) Animation 5.2,
eche br Autoradiography sho thi procedure
Anoıher method font active regions of the brain capitalizes on the fact
ted (for example, by the terminal tons that form
synapses with them) particular gens in the nucle called omnia ary gone are
Verned on and particular proteins are produced. These proteins hen ind with che
chromosomes in the nucleus, The presence of diese nuclear proteins indicates that
‘he neuron has jus been activated,
uclar proteins produced during neural activation scaled Fos. You
will remember that we already did some research on the neta circuitry inves in
‘he sexual behaior of female rts. Suppose we want to use the Fos method inthis
project 10 see what neurons are activated during Female rats sexual a
palate. Then we
remove thera’ rain, ic then, and follow a procedure hat stains Fos prote
Figure 525 shows the reat: Neurons inthe medial amygdala of a male a that
as just mated show the presence of dark spots, indicating the presence of Fos pro

= ‘ity, We place Female at with males and permi the animal to

ton emision tomogrty
Gin ree ch once
sea tein, Th these neurons appear o be activated by copulatory activó —perhapa by

fenton un gv) Amos: | the physical stimulation ofthe genitals that occur then, A yon wll call whem we
le pci ot | injected a retrograde tracer (uorogold) ino the VM, we Toul that this regio

ems e messenenotre | receies inp from the medal amygdala, (See Figure 5.23)
enamel tn, The metabolic activi of specific brain regions can be measured in human
medias Spocrdveice | rains, 100, using a method known as postron emission tomography (PET). Fist,
mos ema re ne | he patient recees an injection of radioactive 200. (Evenly the chemical is

rohen dam and leaves the cell The dose given o humane isharmless) The per
son's head is placed in a machine similar toa CT scanner When the radioactive
olcules of .DG day. they emit subatomic parties calle positrons, which are

206 autoradiogram of art ban frontal con dont easton ffx pein toco how a eta
‘nade the pool, the bs of he bain yeaa Te ear sonia epee or rien,

buon vns smut pring te sina to rg m

157. Shing the ati level

(See Figure 324.)
‘One ofthe disdkantages 0
reasons of safety the n

ET scannersisheir

halves
y very quickly. For
DG is 110 minutes

they decay and lose ther radio
example, the halite

Ah halle of radioactive water (ao
is only 2 minutes. Because th

‘quickly, they mus be produced on
erator called eden Therefore, othe

the PET scanner must be added the
and the lies ofthe personnel who aperate it

The most recent development in br
Funcional MRI (MRD. En

rapidly and permit the measurement of regional metab.

‘ols by detecting ew ge inthe brain's bl

ewes. Functional M higher n

than PET sans de, and they can be acquired mu
denle information about the ac

Ts, they reveal
Aisi of particular brain regions. (See Figure 525)

Measuring the Brain's Secretions

Sometimes we are interested notin he general metabolic

ocu of particular region

pecii neurotransmitter or neuromodulators

in these regions. For example, suppose we know that

acest neuromsin the brain stem participate in
EN sleep. (The experiments that pro
this knowledge are described in the next

this chapter) One of the ch

muscular paras, which prevents us from geting out of
hed and acting out our dreams, We decide wo mesure

pe
motor neurons inthe spinal
croiss.
Sin ich substances ar separated

rons hat inhibi

cedure called
Diatpisivap
bo means of an artifical membrane hat is permeable o

some molecules

dl metal sube that intro

ran shaped in the form of inde, sealed the bot
tom. Another small metal tube ads the solution away
ater i has created through the pouch. A dang of
sich probe is shown in Figure 326

We use sereotarc surgery to place a microdiahsis

rat's brain so thatthe tip of the probe is
ated in the re

lution similar to extracelular Mil

Figure 5.24

Figure 5.25

158. PETER, carter ssa and Sang Rec
Sues LEA

odin A lie sat solo oy ind into the

as apumges

pis

PET xan showing uptake face -DOPA in te aa
bara fa patent putimonn Symptoms indus by à
dopamine neurone (Praparate san San en 3
{hatte ttl amo! vs rt pam.

o e

ov ablongmancom/eartonte

{hough one of the small metal tes into the dats tbs
ing, The fil creates through the diay tubing and
panes through the second metal tube, fom which ts
Taken for anal. As the lid pases rough the dabas
tubing i collects molecules from the extracelular Mid
‘of the brain, which ae pushed cross the membrane by

We anal the contents
toh thei
Hal method. This method f so sensitive that it an

ofthe Mia tat has passed

tect newotransmitters (and their breakdown products)
that have been lead by dh serminal buttons and hate
‘scape fromthe synaptic clef into the rest of the ext
‘ella tid, I act, we ind
‘choline present in the extracelular ido the
{he medula do increase during REM sleep
In a few special eases (for example, in monitoring
chemical of people with intracranial hemorrhages
read trauma), the lerdal procedure hasbeen ap
rain, but ethical reasons pre
so for research purposes. Fortunately

plied w study ofthe hun

there ia noninasive way to mesure neurochemical in
the human brain. Although PET scanners are expensive
machines, they areal versal, They can be nee to lo-
aie any raioactive substance tha emits positrons
Aswesa in the prologue to Chapter 4, several years
ago, several people injected themselves with an illicit
drag that was contaminated wth à chemical that de
Sıroyed their dopaminergic neurons. As a result, they

Suffered from severe parkinsonism, Recent, neuro
Surgeons used stereotaxie procedures o transplant fetal
dopamine msn the bas ganglia of some of
these patients, Figure 5:27 shows PET scans ofthe brain
‘of one of them, The patient ae given an injection of rar
tloactve 1-DOPA one hour before each scan was made,
AS on learned in Chapter 4, -DOPA is taken up b the
terminals of dopaminergic neurons, where itis
verte to dopamine; thus the radioactvy shown inthe
Scans indicate the presence of dopamine-ecreting ter
Final inthe basal gangla. The scans show the amount
y (part) the pa
minis

‘oF radioueity before (art a) and af
tient received the transplant, which great
ns (See Figure 5.27)

his sympto

Stimulating Neural Activity

So fa, this section has been cos
methods that measure the achiy of specific regions of

cerned with research

the brain. But sometimes we may want to artificially
Change the activity of these regions to sce what effect
these changes have on the animal’ behavior. For exam
Ine sex hormones are present If we remove the ras

ormones vil abolish die sex

pl, female rats il copulate with m

159. cong ná Sting Nv! iy AE

+ studies that VME lesions disrupt this behavior.
‘ee wll make up forthe lick of female sex hormones

‘ual havior: We found in our eat

Peshapsit we acto the

and the ats wil copulate again
ow do we activate neurons? We can do o by electrical or chemical simulacion.

Electrical stimulation simpy invokes passing an electrical eurrent hrangh

serted nto the brain, a you saw in Figure 3.19, Chemical

omplished by injecting a small amount fan excitatory amino acid, such as Rain

aci or glutamic acid, to the brain. Asyon Te

‘chemicals
receptors are located
Injections of chemicals into the br

animal see to move about, we can obverve the effects ofthe injection on is
Behavior (See Figure 3.28) Animation 5.3, Comula Implantation, shows hi surgical animation 52, cannula
procedo plantation, contains a

“The prin ation i that ts sig more deo demonstrating the
complicated ie ofa seen apparatus to

tubes, speci pumps oF syringes, Implant a cam inthe ba

tactsates cell bet

les but not axons, Because on
glutamato receptors, we can!
Into a particular rego

cell bodies (and their dendrites, o course) contain

assed that am injection oa
‘ofthe brain excies the cells there, bu

acid
€ axons of

An intra anna. A gi ania permanent sache te sul, and
altera Wines canta canbe red through the gue anna no le
rain chem cn be nad ot brn trough See.

é
| ste
‘ong
ose
a ones a
paste

160. CHAPTER 5: etd and Sates of Resch wor alongman comarienée

wasn magnet simula
tons) Samen ae
oes ect non cal
‘ian pe ent eS
van onto ot
‘Seton soon ta ete

Ths, the effects of chem
he effects of electrica simulation,
A jot sid that ks 1 desenibed car
in, can be use tomate ne eto uses are not really
‘conitadictry. Knie acid produces excitotoxi lesions by sin herons to
death Whereas large doses «concentrated solution kl neurons, small doses
Alte solucion simpy simulae them

What about the resulto our experiment? ac (as we hal sc in Chapter 9)
{VME simulation dos subs or female sex hormones. Perhaps then. the fem
sex hormones exert their effects in this nucleus We wil we how to test this hypo
‘sis in the final section ofthis chapter:

Behavioral Effects of Electrical
Brain Stimulation

Simulation of the brain of freely moving animal often produces behavior
‘changes. For example, hypothalamic simulation can elicit behaviors such as fed
ing, drinking, grooming, attack, or escape that sugges tha th
is involved in thei co ‘of part of the caudate
als omgoing behavior, which suggest that this structure is involved in motor
ion, Brain simulation can serve a a signal for a learned task or can even
serve ava rewarding or punishing event, as we wll se in Chapter 12
There are problems i interpreting the significance ofthe effect of brain tin
tion, especially when itis produced ith electricity. An electrical sama (us
ly series ol pulse) can never duplicate the natural neural processes that go 0
the brain, The normal interplay of spatial and temporal patterns of excitation and
inition is destroyed by the arical simulation ofan arca. Electrical brain sti
‘lion à probably a natural a attaching ropes tothe arms ofthe members 0
“orchestra and then shaking al he ropes simultaneously to see what sey ean py. In
mes ud vo produce a temporary lesion, by which
region is put out of commision bythe meaningles arica simulados
"The surprising finding is that simulation sometimes dae produce orderly
in behavior. This occurs when the stimulation takes place in regions ofthe
{exert modulatory funcions on neural iret located pars of the
«ron inthe basal forebrain in
“are arial imac th
Ividespread release of aclcholine activates the cerebral cortex and Fetes i
Formation processing taking place
Aste sea

in bain se, Transern-

bal magnetic stimulation (FMS) uses coil of wires, wally arranged in the shape
ff the numeral, to stimulate neurons in the human cereal cortex. The stimula
ing cols placed on top of the sl that the crossing point in the middle ofthe

8’ located immediately above the region tobe simulated, Pulses of electricity send
magnetic elds that activate neurons i
those of direc simulation of the exposed bran. For example, as we shall see
‘Chapter 6, simulation la particular region ofthe visual asociation cortex wll di
pt a persons ability o detect movements in visual mul, om. TMS has
Pen ase o trat the symptoms of mental disorders such as depresion,

Figure.

its placement on a person's head. (See Figure 529)

161. can and stung eva! ct MCE
GUNS DISS eR AEE

rar magnetic simulation.) The col wd to apply the lation.) An lation of
iaa tic he mera ema espa ela hi oe

w

INTERIM SUMMARY

Recording and Stimulating Neural Activity
henri of neurons participate in ther normal functions, their electrical ati, meta
Bol city, and chemical secretos increase, Thu, y Obtering these proces a an a
imal perceives varios stimuli or engages in various behaviors, we can make some inferences
about the functions performed by various regions ofthe brain Mioclectrodes can be used
o record the eect activity individuo! neurons. Cone recordings require tht the
electrodo be atached to an electrica socket, which fastened to the kl th plastic ad
eve Macrelecvodes record he acy of age groups of neuen. nate ates macro
(ecrode re placed inthe depths of he human bai, but most often they ae laced on
‘the alp and their activity recorded on à polygraph,

‘Metabolic activity can be mesure by giving an animal an injection of radioactive
2.06, which acumlates in metabolically active neurons. The presence ofthe radiant
real trough autoraiography Ses of the ran ae placed on miroxope se, co
‘ered th photographic emo, otto it white, and then developed ike photographie
‘negatives. When neurons are stimulated, they synthesize the nuclear protein Fos. The res
‘ence of Fos revealed by a special taining metho, provides another nay to discover active
{eajonsof the bran. The metabo activity of various regions af he ing human brain can
be reves by the 2:06 method, but PET scanners used to detect the active regions A
‘other noninvasive method of measuring regional bain activity provided by functional
MR wh detect localized changes in oxygen ee.

‘The screton of neurotransmitter: and neuromodulators can be measured by im
planting the tip ofa micodalyas probe in a particular region ofthe ran. PET scanner
‘an be wie to perform similar observations ofthe human brain,

Researchers can stimulate various regions ofthe brain by implanting à macocletode
and applying mil electrical stimulation. Alternative), they can implanta guide camila in

162. BEREIT cHarten s: ies and states Reset

Table 5.2
Goal of Method Method Remarks
Record cela ofangle Glas or metal mercedes ‘Meal micros can be
ron Implanted permanent to record
‘neural acy av animal menes
Record electrical act of eps Mea marocectroes In mar, say tache to the

Record magnei els induced by
enla

Record metabolic acy regions
Leal

Mesure neurotransmitter and
‘ncuromodlstor released by neurons

Measure neurochemical de ing
human brain

Stile neural cn

Magnetoencephalography: sera
nome whic contains
maras of SQUIDs

206 aworaiogrphy
Measurement ofFo protein

206 PET can
Funcional MRI
Miceli
PET sean

crcl simulan

heal simulation wt exito
amino sd

‘Transcranial magnetic stimulation

scalp witha special paste
Can determine the locaton of
‘group of newrons ring
Sono

Measure local gene ion
denies neurons dat have recent
Pen simulated

Mezsares regional metabolic acy
Avid aie of substances canbe
sabre

Can aie amy rdicive substance
inthe human bain
Stimulates tons near the dp of he
tre and ston passing ough
region
Stimulates on neurone near the ip
ofthe cannula, not axons pasing
tbh ron

‘Stimulate neurons inthe human
«cerebral cortex wan leromagnet
sed onthe head

the bran ater the animal hs recovered from the surgery they inser smaller cannula and
inject weak solution fan extatory amino ai into the bran. The advantage of Ns ro
edu that only neurone whose cell bodas re located nerby wil be stimulated: sons
Pasing through the region wil not be affected. Tarscraniol magnetic stimulation induces,
"cial act in he human cerebral corten whieh temporary dérupts the functioning
‘of neural cuts located here

Table 5:2 summarizes the research methods presented in hi action

Neurochemical Methods
1 have already described some neurochemical methods in the context of damage
ng oF stimulating the brain or measuring neural activi, This ection describes se
«ral ether neurochemical methods that are useful in studying the physiology of

chavos

163. aan nto cul a nens, Dar rea and

Finding Neurons That Produce
Particular Neurochemicals

‘Suppose we learn that a particular drug affects behavior. How would we go about dis
covering the neural circus tha ate responsible forthe deselect Tower this
‘question, les take a specific example. Physicians diconered several years ago that
{arm workers whe had been exposed to certain ypeso insecticide he organophos
phates) had particularly intense and bizarre dreams and even reported having bal
Tcinations while awake. A plawsble explanation for thee symptoms hat the drug
stimulates the neural cuts responsible for dreaming. (Afterall dreams ac hal
‘nations that lsleeping) Alternative the drug could arp inhibitory
tcehanims hat vent dreaming while wear awake, Other evidence (ih wil not
Be deere here) indices that the former hypothesis rue: Organophosphate
scctcis direct ache the neural circus responsible for dreaming,

The ist question o ask relates to how the organophosphate insecticides work
Pharmacologsts have the answer: These drugs are acetteholiesterac inhibitors Av
sou Tearned! in Chapter 4 acesicholinesterase inhibitors are porenaceyicholine a
‘hiss, By inhibiting ACHE, the drugs prevent the rapid destruction of ACh after i
release by terminal buttons and ds prolong the postsynaptic potentials at ace
chotinergie

we understand the action ofthe insecticides, we know that these drugs
act at aceyicholinengic smapres. What neurochemical methods should we use to
discover the sites of ation of the drugs inthe brain? There ae thre possibilities
‘We could look for neurons that contain aetjcholine. we could lok forthe enzyme
acelcholineserse (hich mus be present in the postsynaptic membranes of cells
that recehe qmaptic input from acetlehotinegie neurons), or we could look for
aceiyleholine receptors Les ce how these three methods work,

Fi, es consider methods by which we can localize particular neurochemical
such as meurotransmiters and neuromodulators. (In our ase we are interested in

acen
Tocalizing the chemicals themscles or the envymes hat produce them.

Peptides (or proteins) can be localized rectly by means of immunocyto
chemical methods which were described in the firs sctin ofthis chapter Slices of
rain tise are exposed 10 an antibod for the peptide, inked to a dye usualy a

one) There are two basi was of localizing neurochemicals in he bran

164. MITE carrer 5: cs Ste ot wo ablongman.comventzonge

Auorescent dye). Th
particular va
brain. sows up asa ru color. The other st, scared through the ao
looks like strands of gol bers (As on ean se, a propery stained bran
De besa See Figure 830)
Bat we are interested in acetcholine, which i nota peptide. There
find this neurotran

tre cam us these me

Localizing Particular Receptors

Aswe sv in Chapters $ and 4, neurotransmiters, neu
Fomedulaten, and es convey their messages to
their target cl y binding with receptors. The k

be determi

Figure 5.30

ceptor Next, we se
them is that of the molecules of the ligand bound to
phic me

thelr receptors. Final, we use au
‘cso localize the radioactive ga thus the re

Figure 5.31
ren “ec ME rosa me ,

165. ceptors, Figure 5.82 shows an example ofthe res of
{his procedure, We see an autoradiogram ofa alice of a
rat brain that was waked in a solution that co

‘ioactve morphine, which bound with the bra
receptors (See Figure 532)
The second procedure uses immunocytochemisty

Receptors are protcins therefore, we can produce ant
bowie against hem. We expone aces of brain sue o.
the appropriate aby labeled with fluorescent de)
anc look atthe slices with a mieroscope under light ofa
particular eavelength

Lets apply the method for localizing receptor tothe
first line of investigation we considered inthis chapter
the role ofthe ventromedial byposhalanns (UME) in the
sexual behavior of female rat. As we su, sions
‘VME abolish thi et
docs ot occu if the rat's oxatics are remaved but tha it
‘can be activated by simulacion ofthe VMI ith electro

her amino acid. These result agen that

hormone produced by the ovaries act on newton
This hypothesis

gests wo experiments, Fine we
cand use the procedure shown in Figure 538 10 place a
Small amount ofthe appropriate sex
into the VMH of female as

y removed, As we shall ce in Chapter Y this proce

‘dure works the hormone dor reacia the animals
sexual behavior, The second experiment would us a
toradography to look for the receptor for the sex hor
mone. We would ‘expose 4 a brain to the
Fadisctve hormone, fine them, and perform autora
‘ography. If we did so we would indeed ind radicactity
inthe VMH, (And fe compared slices Irom the brains

female and male ats, we would find evidence of more
ñ

se immunocytochemistry o loc

monte receptorsin the females brains) We could also
ze the ho
ceptor, and we would obtain the same resus,

INTERIM SUMMARY

CRUELES,

In autoraiogram of rat rin (orion sco, otal at
{op tat war cated sin comi ros
Incas whe ea

Neurochemical Methods

substances inthe brain. They an entity neurons that secrete a partiuarnewrotansmt
ter or neuromodulator and those that potest receptors that respond tothe presence of
these substances. Peptides and proteins can be dec localized, though immunogto
chemical methods; the tue i expored to an antibody that Inked to a molecule hat
force under ight ofa particular wavelength Other substances can be detected by i
rmanocytochemia localization of an enzyme thts require for her synthe.

Receptor for neurochemical canbe locale by two means, The fst method uses au
tecaciograpy to reveal the distribution ofa radioactive ligand to which the tue has ben
‘exposed. The second method uses immunocytochemisry to detect the presence ofthe e-

Captors themselves, hich are protein

Table 5.3 summaries the research methods presented in this section.

166. Table 5.3
Research Methods: Part

Goal of method Method Remarks

Ten neurons producing Immenco
partir neuroranemier or pep or
‘euremodulaor

emia locaton of Renuiena speciicantbed

Uso fsb
ee

pari po pete ceci lene

AU behavior determi
Many a

tions been an individual bra

factors may play a role inthe development of physiological differences tat are ul
for these characterises In some eases the genetic Tink i very

‘lear: A defective gene Imereres wih brain development, and neu

normality causes behavioral deficits. In

teh

them.

dor netic methods must he used o

nich more subie, and speci

Twin Studies

A portal
1o compare the reneanfance mie or this tat in pairs of mononygatie and diygote

‘wins. Monoeygotc twine (identical ins) have idemical
genonyperiha is their chromosomes, and the gens they
onan are demical I

tween digo ins
percent. Investigators study records to ¡demi pars of
{ins in which at lest one member has the traitor ex
ample, a diagnosis of a particular mental disorder: both
twins have been diagnosed with thi disorder, they are sald

tthe genetic similar De
nal wins) fon the ave

tobe nement only one has received his dlogods the
twins ares 0 be dicndat Ths, ia disorder has a ge

is willbe higher than the per
‘centage of dizygotic twins For example, as we wll se in

netic basis the pere
concordant forthe dag

Chapter 15, the concordance rate for schizophrenia in
twin a last four times higher for monorsgotie seins
than for dizygotic twins, a Finding that pronide strong ev
idence tht schizophrenia a hertable trait. Twin ses
have found hat many individual characterises, including

Te le eee nement secopnent holism, and a wide variety of mental disorders, are inf
‘Hpac boe ats enced by genetic Factors

167. ‘Adoption Studies

Another method for estimating the heritability fa particular behavioral trait 10
‘compare people who were adopted car in life wth their biological and adoptive
parents All behavioral traits arc affecte to some degree by hereditary factors, en
‘ronmental factors and an interaction between hereditary and environmental fac-
torn Environmental factors are both social and biological in nature. For example,
the mother's health, mutrion, and drugtaking behavior during pregnancy ae pre
natal environmental factors, and the child’ det, medical cre, and socal enston
ment (both inside a environmental factors. a
‘hil is adapted soon alter birh, most ofthe postnatal environmental actors wil be
‘associated wit the adopt y genetic Factor wil be associated with the
biological parents, and the ronmental actors wil be associate with
the Biological mother
Adoption studies require that he investigator now the identity ofthe pa
ing sie and beable to measure the behavioral ait in the biologie
stale strongly resemble

miso

out posible di
‘ofthe adopted ch instead, the people resemble
“once that the waits nluenced by environmental factors. (I
Study to determine just what these environmental actors might be.) OF cours it
possible that both hereditary and environmental factor play role, in which cave the
pope being sie wil rexcmble both their biological and adoptive

Targeted Mutations

fe chromosomes of mice. These mulated genes (alo called knockout genes) are
Aefectve—They alto produce a functional protein, In many cases the ange of the
‘mutation san enzyme that controls particular chemical reaction. For example, we
will ee in Chapter 12 that lack ofa particular enzyme interferes wth learning, T
Felt suggest that the enzyme i partly responsible or changes inthe st

er caes the target ofthe mutation i
the eel, For example, we wll se in
a paricular ype of opiate receptor iinvohed in de reinforcing and
analgesic effects of opiates.

INTERIM SUMMARY
Genetic Methods

Because genes diet an oxgansm’s development, genetic methods are very useful in stud
les of the physiology of behavior. Twin studies compare the concordance ates of monory
otc erica and dzygoi (raten) twins for a particular wat. A higher concordance
Fate for monozygotic twin provide evidence tat the rai inlencea by here, Ado
tion studies compare people who were adopted during infancy with ther Biologia and
adopte parent the people resemble their Bolgia parents evidence seen for genetic
factors. ifthe people resemble their adoptive parent, evidence seen for a role of actors
inthe family environment.

Target mutations permit neuroscientists to study the elects ofa ak of particular.
protein Jr example, an enzyme, structural rotin, oF feceptor—on an animals physio:
ogi and behavioral characteristics.

ne

168. THOUGHT QUESTIONS.

1. You have probably red news repo about studies of he genetics of human behav-
oral traits or sen them on een. What do really mean when a braten

report the discovery of, ay a "gen fr shyness"?

Most ats donot appear o lt the taste of lool, but recarchrs ave bred some

rat hat wll koh in Large quantities, Can you think of ways se these

animal to investigate the possible ole of genetic ators in alcohol in humans?

Watch the Brain Waves

wnat wen wrong? Why dd Ms.
"succes surgery causes neuroeg
cal problem? nd can anything be done
rer

Fit lets cones th cau of he
pren here viral machine
rari heat created M M
ood hie the surgeon was removing
woot er coronary arteries and rep
Ing nem th eins taken rom here.
The output ofthe machine ajusta;
‘hat the person operating ican one
{ul the patients lod pressure. The
Surgeon visto kee he lod reste
Justin enough to ss th paint
Bun ot o high ato metro wih he
‘eat surgery ont coronary ate
der Unortontey Mr. Hs coronary a
teres ere nt the ont ood neh 10
‘be patil Docs; he arteries in er
‘gue When the machine ook ove
{he clan of her lod same prs
other brin received an inadequte
‘ood flow and he tin these re
ons ver damaged

MES H's Blood presu had been
maintained at signo per ee ur.
Ing te urgen her bain damage mit
ave been prevent For most patients
‘the lod pressure woul have Ben su

‘et b inher me vas ot Me
Hi domage reverb, bt re
‘here sep tat can Be taken o prevent
‘othe rom sharing her fate?

The answer sy. The sation sto
se a metho sere in a apte
‘etroencepbalgraphy. What we eed
‘sa waning tem tote the surgeon
thatthe brain not recen aa
‘ent bead flows that he ose can
‘just te machine and Ines the po
ent blood presure That warning can
‘be provided by an EEG. For many yeas
‘lineal lecoencaphalagaphers Gpe
‘alts who perform EEG edge
auroogal deren) Rave known tht
ie widespread bain damage
“sey varius pons, ano o en.
tremely ow ees of blood gion pro
ducs slowing ofthe regula hm
pater ofthe EEG Fortunate, ths pat
fern begins ight may. 25500 se
damage commences. Thus Eads
te attache to a potent underging
Carla urgen an lncoencepalogra
Pre can wat the recor coming it
{he polar and nar tn surgeon #
{he recor mos owing does, he
Paint lod ow canbe increased
brain damage canbe averted

sv ablongmancom/caronée

Mes Hs peated on ove 15
un ago ata tine when on afew
re nage had te patients
San wees monitored Today the pat
ce common and tied dung
espa cdi ama
ie when the croi ares (eves
Ses var pronde most of he eins
Bond sup become obstructed by a
«rose plage, surgeon an ut
open the arteries ad remove the
plaque During this procedure, ale
Caro encoerctor amps must be
paced on the creta artery completely
‘oping the loo ow ome pata
Can tlerate the temporary camping ot
one art artery without damage oh
note EG record shows o.
Swing whe the artery amped the
Surgeon can procad. does he sr
gran mus place teens of pase
{bet re artery above ad low
the clamped region maintain acon-
‘anon flow Ta procedure ne.
{othe patent o mat surgeons woul
preter todo on meta The EEG
Bordes he esentalintrmation

EXPERIMENTAL ABLATION
1 Xe
the
inthe animals bos

fotrytoinfer 2 Brain lesions may be produced in
tran by ping electrical current through an elec
tre placed there or by infusing am excitatory

I depths of the

169. acid the later method kills cells but spares axons
that pass through the region.

3. The behavior of animals with brain ions must be
compared with that ola control group conssin
animals with sham lesions.

‘stereotaxic apparatus i used to place electrodes
isin particular locations in the brain. The
reotaie ala

The oca
tological
microscope
Special histological
race the afer
ticular brain region,
The structure ofthe living human brain can be re-
seed dhromgh CT scans or MRI scans

Jods have bo
deerent connec

devised to
ons of par

RECORDING ANO STIMULATING
NEURAL ACTIVITY

‘The electrical activity of single neurons can be
recorded wth microelectrodes and that of entre re
ions ofthe brain can be recorded with macroelee-
trodes, EEGs are recorded on polygraphs and
recorded from macroclecrodes pasted on a per-
son's scp,

9. Metabolic activi’ of particular parts of animals

brains can be asc by means of 2DG au

Ses tes

‘ography or by measurement of the production of
Fos protein, The metaboli activity of specific e
ions of the human brain can be revealed through
PET scans or functional MRE sc

0. Micros permis a researcher to measure these:
retion of particular chemicals inspite rogions of
the brain,

11. Neurons can be simulted letrclh; ong lee

te solutions of

NEUROCHEMICAL METHODS

12. Immumoeytochemical methods can be wed to local
ine peptides inthe bra enzymes ha

ds and asecaing the ress
‘vith autoradiography or immunocytochemiry

GENETIC METHODS

14. Twin studies and adoption studies enable invesign:
tors to estimate the role of hereditary factors i a
particular physiological characteristic or behavior

15. Targeted mutations are artificial produced muta
tions that interfere withthe action of one or more
genes, which enables investigators to study the el
fectsof the lack of particular gene product

STEREOTAXIC ATLASES
Paxinos Gand Watson, C The Rat Bin Sti Cont
tthe San Diego. CN Academic Pres, 198
Sonic, Mand Load. Co M, Sort Mla of A
‘hn Moe mi. Rockall MD: abe Healh Sere
1975. (US. Ganernment Ping Off Stack Number
Shier RS, and Niemer W.T A Stree Aas e Ct

Sanson LW. Brin Map: Sate ofthe Rat Brin ste
‘ar: Ee, 12

HISTOLOGICAL METHODS.

cimer L and Zábordy: L. Normal! Tec Ting

One Mendelian Iberance
‘vc lh goon!

iones Research Methode
voir ante

Proctor means cime moler io e

“Tatra of Funcional MRE
mi es au -nabgrg mi
This se provides an advanced ane o the fc
[MRI technique and pones cmprehenshe reference for

170. Vision

Describe the characteristics of light and colo, outline the anatomy of the eye and
ts connections with the brain, and describe the proces of transduction of visual
Information

Describe the coding of visual information by photoreceptors and ganglion cellsin
the retina

Describe the striate cortex an dius how its neuron respond to orientation,

movement, and spatial frequency.
Discuss how neurons inthe state cortex respond to retinal party and colo,
and explain the modular organization of strate cortex

Describe the anatomy ofthe visual association cortex and discuss the location and
functions of the two steams of visual analy nat take pace thee,

Discuss the perception o color and the analysis of form by neuronsin the ventral
Describe the two basic forms of vial agnosia: apperceptive visual agnosia and
asociatve visual anni

Describe how neurons in the visual association cortex respond to movement and
location and discuss the effects of brain damage on perception of these features

The!

Anatomy ofthe Visual

System

of Visual

Information inthe Retina

Analysis of Visual
Information: Role of the

‘State Cortex

‘Anatomy of the State Cortex

formation: Role of the
sua association Cortex

Perception oS

171. Seeing with His Hands

‘ne Sunday moning. acoenque ced puzing over a piaure facon he held people n which tes ar represented
me and sted whether! wuld le to MS together and started makingal by parlar hand and ger move

Imeethim ata nearby hosp inter tematngupanddenm movements mens M sem 6 commany alos
‘ew pair with an interesting dor- M them. Unmitakal he was ating ner pling) Se showed M. et
‘er jones im there and met she were miling cow Helooked ter and ske him 1 soy whatit was Me

pesant mann ie miis Me M. than andi, “Oh acom” he wasurabletocdoss Tren ela
ud sine brin damage from anin- laughed Tico form, you know" ‘finger and moved tem ino the pon.

ammatny dose ha afectos the ete rm ati tendent ion us “pele the ete Over se
lod ves M brin Hp ap mule moments at pe im se” erlssions e as bl ech him o
eater be normal buthebad great Dingemas fest acoeredbyaspech male De pope movement whichhe
Fiat recognizing obje e pues — tempe Teba image ad de- odo eventhough he ws unable to
fofthem Wewenthroughaboeket stoyedhisabitytoreodasselasto Say tener was Once Angers
tres ha sordmaniysedtotest recoge objets andshewastningo moved he oud fel he poston and
nie vocabularies and fund Pp megan ths aby Shewanted Soywhat heiter mst be. He was abe
thathe was unable to soy what many ol topa on the potential hs Val to se hs abil to read whol werd;
temer. Homer he sometimes pepo to tiger automaichand looked t nia eters of» word,
(made unintentional gestures when be movement even hough he un made the appropiate movement ob
‘tas studying à pure that gave hm desc thse perceptions ina seed the sequence of ters that he
“rough of e o den Forex Therefore medido ty totexh spelled andacognand the word The
ple on one ocasion le hewas the manu ape edb deat proce wa son Et woke

se a train performs ne majo fune
A sn ii macs pco enon, sg he

body internal environment. To perform both these ks, he brain must be

informed about whats happening both in the external envionment and

bods Such information Irecched by the sensory systems Thischaptera

are deso toa discusion of the ways in which sensory organs detect
ment and the ways which the bran interprets ncural sig

ion about the environment rom sensory reeeptors—spe-
laze neurons that detec a variety of physical events. (Do not conte mar re
on with receptors for ncuru neuromodulators, and hormones
Sensory receptors are specialized er pes of vce
lized proteins that bind with certain molecules) Still impig on the receptors
“and, through various processes, alter their membrane potentials, This process
Known av sensory traneduction because semsory events are ranuuent Ctramierred”)
into changes in the cell membrane potent, These elecwical changes ae called
receptor potentials. Most receptor lack axons portion of their somatic membrane
as apres wih the dendrie of other neurons. Receptor potential affect the
ran hence modi the pattern of ring in neurom

‘release of neurotransmi

ich these cells form synapses. Ultimatel, the information reacties the bra sensor meeptor à scans
“This chapter considers vision, the sensory modaly that receive the moat a | von ut orcs spas
tention from psychologists, anatomist and physilogis. One reason for hi aten… | 99791 ns ee

| ptes

on derive rom the fascinating comple of the sensory organs of sion and
relatively large proportion ofthe brain hat x devoted tothe analysis of ial infor
‘mation. Another reason, Fam sure, hat vision iso important to us as individuals

ura fascination with such a rich source of information about the world leads

how this sensory modality works Chapter 7 deals with the other | ro Patent ow
sensory modales audition, he vexbularsemes, the somatosemses gusaion, and | Zag y amargo ce,
fon. Sean pyc Sms

155

172. ETD carre 6: von

worwablongman convento

The elecomagnti cum.
Mmolngni ananas
so E) 70
Pl [une Radar ac eus

wreath

‘sights On of e pere
meme of clr tray
sstravon One oft pe
‘cond ye

Boten ces mod on
198 One fe mc ct
toon

photoreceptor Oe! hee
es prove ey cal

rset ny ype at

ie radiation with
rion of a me
ter à vie 10 us. (See Figure 61) Other animals can detect different range of
lectromagnetic radiation. For example, honeybees can detect difference in ts
viole radiacion reflected by flowers that appear white o us, The range of wave
Tengihs we cal gis no qualitatively diferent from the rest ofthe electromagnetic
spectrum itis simply the part of the continwum that we mans can sc

The perceived color of ight is determined by three dimensions hu, saturation,
and res. Light travel at a constant speed of approximately 30,000 kilometer.
(186.06 mies) per second. Thu, he frequency fonction of the wave varies
the distance betwscn the peaks of che waves wil sity vary, bu in inverse ae
ion. lower oscillations lead to longer wavelengihs and far ones lea
sanclengihs Wavelength determines the frst ofthe thre perceptual dimensions of
Tight: hue. The vibe spectrum displays the range of hues that ur eyes can detect.

Light can also vary in intense which corresponds to the second percep dí
mension of ight: brightness. I the intensity ofthe electromagnetic radiation in
read, the apparent brightness increase, too, The third dimension, saturation,
ler tothe relative purity ofthe light that being perceived, Ital the radiation e
‘fone wavelength, the perceived color is pte, or fly saturated, Converse ithe
radiation contain all wavelengil, it produces no senation of huit appears
‘thie, Colors with Intermediate amounts of saturation consis of different miss
lt eavelengths Figure 6.2 shows some color samples a with 0
“diferent levels of brightness and saturation. (See Figure 62)

For an individual to ee, an image mus be focusedon the reina,
the eye This image causes changes in the electrical ac

the reia, which results in messages being sens through the optic nerves to
ofthe brain. (suid “the ves” because the retina sac

the optic nerve are in the central—not pe system.) This section
describes the anatomy of the eyes the photoreceptors in he retina hat dee:
presence of light. and the connections between the retina and the bran,

173. The Eyes

Some animal uch thi honjbe, an detect wavelengths

The eyes are suspen! in the ers bony pockets the front of the skull They are
hel place and moved by six extraocular musclos attached to the tough, whit
‘outer coat of the ee called the sla, Normale cannot look behind our eyeball

(ts preventing a contact tens that has lipped off the cornea from “alg behind
the eye) Figure 6 ilutrates the anatomy ofthe eye (See Figure 63)

The outer ayer of most of dhe je, the sclera, is opsque and docs not permit entry
fight However, the cornea, the outer ker atthe front of the eye transparent and
sgh. The amount fight hat enters sregulatd by the size ofthe ppl which
isan opcningin their the pigmented ig orme stated hind the cornea. The

Jen stated immediate behind hers like

tan objects on the rtina—a proces called accommodation.
Alter passing through the lens, gh traverses the main part of
the eye whit filled with tows mer (psy quid" a clea

hou sbsanee Aer pasingthrogh he Miro humor
High lon rt, the mentor ing ofthe back of thee
In the retina ae located the repr cel the rods and cones
ated fr ei shapes), collie Known = photoreceptor

es or ea (om aan, "nee. The Foren or central region

‘icriminate light of different wavelengths. Athough rods do not

AS

So E one
Er
CRE
a Eon
Decreasing ud

174. ep dk recon ote
Feet of gngon es
tem be ope nee, oan
nc ca ro
tem been ne
dir cl Armor as
ima tom par ces
oran eal noon
ear te bgt cts

D ado pn an
Beier pos ol best

ablongmancomrsonée |

iy, hey are more sensitive 10
rod ihn therefore. in dim

Tight we ate coor lind and Lack foveal vision. You may have noticed, while ot on à
dark night, that looking direct adm, sant ight (shat placing the image of
the ight on the fovea) causes it to disapeat (See Table.)

Another feature ofthe retinas the opie dis where the axons conveying visual
information gather together and leave the eye dhrugh the opie nerve. The optic
clk produces Mind or becams no receptors are located there, We do not normally
perceive our blind spots, but their presence can be demonstrated you have not
Fouad yours, you may watt ey tne in Figure 64.

"Choe examination ofthe retina shows that i consists of several ars of neuron
cel bodies, their axons and dendrites, and the photoreceptors. Figure
Aero section through the primate retina which ide into three ma
photoreceptve layer the bipolar cel layer, and the ganglion cell aye. Note that
the photoreeptorsareat the Back the retina i reonering
layers to get 0 them, Fortunate these layers are wansparent. (See Figure 65)

Table 6.1

175. anstonyot ne son AECI

ts forthe bind spot WIN your ft pe cr, ak a he + ith your it eye a move he
Page nearer to ad forthe om you When the page atout 0 m om our fc, the gen
ice dape heces image aon he Bin poto your rah eye

ù 8

pte sk
(Bins soi roves

“The photoreceptors form synapse wth bipolar cll, neurons whose two arms

‘mit information ina the surface ofthe retina nd thus combine
‘messages from adjacent photoreceptors (See Figure 65)

The primate retina contains approximately He different pes of neurons:
‘one pe of rod, three types of cones, two tes of horizontal cells ten types of
Bipolar cell, wentsfour to twensunine types of amacrine cells and ten o iin.

topes of ganglion celle (Maland, 2001),
roten Layer poa Catiajer __GangionCotLayer

@.
A
Ca

<= un al amer

Back
ES

IS LE BGR RE TA,

176. Lama à pe of membrane

photopigment à ten de

eta retin) Actes
propa,
‘epi doe) Ao

Figure 6.600 tis

ev ablongmancomieaanée

Photoreceptors

Rods and cones consis of an outer segue
im ontains the nucleus. (See Figure 65) The outer segmen contains se
‘ral hundred lamella, or thin plates of membrane. (Lamella the din

‘flaming “in er)

Tet’ consider the nature of transduction of visa
the chain of events that leads to vial perception imohes a special chemical called.
aphotopigment Photopigments are special molecules embedded inthe membrane
‘ofthe lamellae: a single human rod contains approximately 10 million of them, The

olecles consi of two parts an opain (a protein) and retinal (pid), There are
several forms of ops; for example he plotopigment of human rds, rhodopsin,
Consists rl psn plus reina. (hal eters tothe Greek ran, “ese,” not od
Before iis bleached by the ation of ight, hopin has pinkish hue.) Retinal x
synthesized from vitamin A, which explains why carrots, which are rich in this ita
in, are said to be good for your eyesight.
‘When a molcenle of rhedopain i exposed 1 ih, it breaks i

stituents rod opsin and retinal, When that happens, the rod opsin changes rom i
tow color to. pale yellow: hence, we say thatthe light Meche the photopigment,

ected by aci

The spliting of the photopigment cause change in the membrane potential of the
photoreceptor (the receptor potential), which changes the rate at which the pho-
receptor releases its neurotransmite, glutamate

Inthe vertebrate retina, photoreceptors prone input to both Bipolar eels and
horizontal ells Figure 6.6 shows the neural circuit from a photoreceptor to agan:
lion cell The citculry is much simplied and omits the horizontal cells and
“mucrine cell The first wo pes of els in the crcuit=pho
toreceptors and bipolar cell do not produce action poten

sad, their release of neurotranmiter regulated by

the value of their membrane potential; depolarizations i

Neural ray nthe retina ight ing a potoreceptor
frovuceshyperpdonaatan se the protege ewes crea the release, and hyperpolaiations decrease it The
Fo nooo Sense he reuroraramiternomalyy circle indicate what would be seen on an oxcilocope screen

radin asa ceplrestian Tha depot causes

eto

pero the membrane ofthe ipl al he recording changes inthe celle membrane potentials in re
Sponse toa spot of ight shining on the photoreceptor:
"The Inperpolariing effect of light on the membranes

po ne
Paco rena

cot wa ee où
rer o

im

Ries Vom bong.) ma tricone Torn Sua
rem ean y E Sein dt on Coto, Mas net €

of photoreteptors i shown da the I
Meng polation nurs the elas of newts
A, photrcccpior. Becas the nena

Pespotarizesthedendrtesofthe ip cel a
rules canes the membrane ofthe bipolar elo dlr
Thu ight hyperpolarizes the photoreceptor and depa
inc the bipolar el. (See Figure 66) The depolarization
causes the bipolar cell to reese more neuroransmier,
> Sic depolaic the membrane of the ganglio cell ce
ing to increase rate of it shining on the

photoreceptor ete xc
“Te cet show in Figure 66 states ang
cell whowe fing rte increas in response to light. As we
cr ganglion cells dec thee ing ae in re.

Spomse wo ight These neurons are connected to bipolar

Celle that form ere pes napus withthe photo
rl Tem ceptors The functions these wo pes oran

‘ot ‘ste a ter section, “Coding of Via Information in

the Retina” I you would lke to know more about the
ry oF Ave retin, you should ons the book

Ip Radice (1988),

‚ph. The byper

177. Connections Between Eye and Brain

“The axons ofthe retinal ganglion cel bring information tothe rest ofthe brain.

tin for "kn von, cach of which e

y one eye. The neurons in the o inner layers contain cell
bodies that are lager than how in he ae our avers or this season, the inner
wo lara are called the magnocellular layers, and the our four layers ae called
1 parvocellular layer (ara refers tothe smal se of ue cll) third set of new
‘rons inthe Koofocellular sublayere are found ventral to cach of the magnocellular
And parvocellular Layer. (Kom the Greek word for “ls As we will ee later
ese thee sts of ayers belong to different systems which are responsible forthe
analysis of different pes of visual information, They receive input from different
"pes of retinal ganglion cells (Sec Figure 6,7)

The neurons in the dori lateral geniculate nucleus end their axons through
2 path known asthe api radiations o the primary visual cortex he region sur
rounding the clcainefisue (aline means Sspueshaped”) a horizontal Fissure
located in the medial and posterior occipital lobe. The primary tal cortex i oF
ten called the striate cortex because I contains a darkstaining layer (strain) of
el,

Fig
rain The optic nerves join together at

€ GA shows à disgrammatial view of horizontal section of the human
1 ase ofthe brain to form the Xshaped

A potemogrph of secon tough the ht
(espe sta Les an rece out on he orale ef ey. and oes 23
And ren input Hom ter igh eye Layos ana 2 are he magna es
iter 310 arte parca pers The noc tija lora etal ogo of
‘he parece and mognocl ter yer The capte Hel al Sa pira es te
In mo pre gone cate tng the nef te unlabeled srw hoe receptive
‘el centered on he ome post.

net
frat un es ers ne

pacar ont
Sst gence nes.
lerpeceston cours ine
tenia ubayer uch ne
ham yu One e
ro ee
Tract Den,
Wengen teense
‘aaron ase ar) A
{ae ne poser eta co
ae acer fh pny
tte core st) The

Fama D Wands PRE Tao PONSA E

178. REED cHarren 6: vison
Figure 6.8 pie ia Ahan means “er er aa

‘The pint sa pat sal sides) cross through

‘wernabloogman.zondconte

santo cell sersng the nner ha of

Pr dora lateral geniculate mues ofthe opposite ide of
AS he Brain. The axons from the outer haves ol he retina

pcia ya) a cos
Pb sand

(the temporal sides) remain on the same side of
brain. (See Figur 6.8) The lens inverts the image ofthe
(and similar reverses elt
“and righ). Therefore, because the axons from the nasal
halves ofthe retinas ross othe oer side ofthe bra,
‘ach hemisphere receives information from the cor
incesante lateral half (opposite side) ofthe visual scene. Th
laa ¡Ca person looks straight ahead, the right hemisphere re.
‘cies information from the lit half ofthe ital eld,
And the lett hemisphere receives informa
ght (See Figure 68)

Besides the primary reinogeniculocortical path
way, several other paths are taken by fbr from the
ina. For example, one pathway tothe Insporhalamus
synchronizes an animal's etsy eyle to the Zichour
hs of day and night. (We wll dy thi tem in
“Chapter 8.) Other patina, especial those that travel
Pray to the optic tectum and the preteta nucle, coordinate
Weve!” eye monements, contro the muscle ofthe rs (and ts

ei of the pupil) and the ar muscles (which con
ol he lens, and help to dire our attention to sudden
‘movements inthe periphery of our sisal fil

Opisensem

on fom the

The Stimulus and Anatomy of the Visual System
Lig consists of electromagnetic raiaion similar to radio waves but of a diferen fre.
‘ene ad wavelength. Color an vary in ee perceptua dimensions: ue, bahnen, and
Saturation, which rend to the phil dimesions of wavelength, nens and u

fi respectively.

“he phototeceporsin the etin—the os andthe cons detect ight. Muses move
‘the eyes 3 that images ofthe envionment al on the retina, Accommodations accom
bled by ey muscles, whch range the shape ofthe ln. notorcaptor comm
Ficte through synapses with Bipolar cel, which communicate through synapes with
ganglion cel nain, horizontal cel and amactne ells combine mesas om a
en photorecentons

‘When ight sites a molecule of photpigmentin a photoreceptor the etna melee
<etaches om the opin molecule, a proces known as bleaching This event causes the mem
brane potential to become more polarized. This change in the membrane potential de.
‘eases the lease of glutamate and informs the bipolar cel ith which the photoreceptors
(Smmunate that ight has jst been detected. As est of his proces, he at of ring
‘ofthe ganglion cl hange anda message sent though the ston of he optic ere

‘aval information from te retina reaches e state cortex surrounding the clase
‘sure afer being relayed trough the magnocella, parvocelar and Konocti ay.
‘of the dorsal tra gerclate null. Several other region of he rain, Inuding the
‘ypotalamus and te tectum, abo receive vial nformaten These region hl to segu:
{at activity during the day-night eye, coordinate eye and head movements, conto at
tention tual imu nd regulate the ire of he pup

179. TMOUGHT QUESTION

People who tr ose fant. an lights a night are often as 1 look justo the
id of he location where they expe to ee the lights, Can you explain the reason fr
this vice?

This section describes the way in which cell ofthe reina encode information they

receive from the photoreceptors

Coding of Light and Dark

One ofthe mostim

ortant metho for studying |

the photoreceptors with which they com

sal tem is the par ofthe vital il

physiology ofthe visa system
‘of mieroeleciodest record the electrical atv of single neurons, Awe
‘iin the previous section, some ganglion cells become excited when i
nicat, The receptive field of a neuron
at an individual ne

sus

Falcon

thas the parti which ight mus fl forthe neuron 10 be stimulated. Obsionsy

a he receive fel fa particular
the photoreceptors hat provide i with ssl informatio
ormaton from photoreceptors located inthe foca,
sion point—the point at which the eve is looking. If
vil be locate off 0 on

A the periphery of the re
ganglion cel, ringing information fom 16

ea relatively large area o the visual ld, However
foveal vision is more direct, wth approximately equal

numbers of ganglion cell and cones. These receplorto-
om relationships explain the fet that our foveal (ce
tral) vision every acte but our peripheral vison much
les precise, (See Figure 69)

‘Over say years ago, Hartline (1938) discovered
the frog retina contained three types of ganglion cells
(ON cells responded with an excititory bunt eh
retina was illuminated, OFF cells responded a
Tight was turned off and ON/OFF cell responded bricly
sen the light went on and again when it went ft Kut
Mer (1952, 1953). recording from ganglion eels in
retina of theca, score that ther recepive fel con.
sins ofa roughly circula center, surrounded by a ring
Simulation of the center or wironnding fields had con:
teary effect ON cell were excited by Hight alg in the

bite by ight fling in
the surrounding Held (surmund, whereas OFF cells rc
sponded in the opposite manner ON/OFF ganglion cells
‘were briefly exched when Tight was turned on or of. In
primates these ON/OFF cells project primarily othe st
pertr colliclus, which is primarily involved in visual re
lex (Schiller and Malpeh, 1977) ths, they do not
appear vo play a direc oe in form perception. (See Fig-
e610)

side

à many individual receptors
ively large ara ofthe re

rom depends on the location of

Tea neuron recehen ie

a wll he atthe

euro receives Infor

1 from photoreecplorslocated in he periphery ofthe retina, is receptive ici

ent ves peripheral acy Ganglion ein he ovo recive
‘rout tom a sta umber o porno tha nthe
‘every and hence provide Mae so sl erat:

Receive ein center
‘Styne fovea,

Pécagve tin
Pare ole,

180. Ez Si.
h mw (©) |

and OFF
Seiler

{Zaina de that inch
on in ON bipolar cell

ad ficult detecting igh

14 but had no dic den

achgronnd

Coding of Color

he monochromatic prop
mis of ganglion cellethat i heir responses 1 light
and dark But, of course, objects in our environment se

New World monkey,

tds ave reecone ue toc us return [uit From unripe Fruit and made Ht more diia for

end yrs maar athe ret gt bed ‘other animal ta hide themselves by means of camouflage

181. (Mallo, 1989) In act, the photopigments of primates with three types of cones
seem weil suited for distinguishing ve and yellow frit against a background of
gen Fag (Regan et al, 2001

Photoreceptors:Trichromatic Coding

1 color vision have been proposed for many years—iong before
itwas posible to disprove or validate them by physiological means In 1802 Thomas

Young Bish ysis and physician, proposed thatthe eye detected different col

‘ors because it contained thee types of receptors, cach sensitive o a single he. His
theory vas referred toas he fichnmatic(Uhteecolor) hor. I vas sgte by the
Fact that fora human observe any color can be reproduced by mixing various qu
ties of three co

or judiciosy selected from different points along the spectrum
Trust emphasize that color ising diferent from pigment miing we combine
yellow and ite pigments (as when we mix paint) the resulting mixture is green.
Color ming refers to the addition of two or more ight sources I we shine a beam
‘fred ight and beam of bluish green ight together on a white seen, we wll see

Sell light If we mix yellow and blue Hight we et white ight When white appears
fn a color television screen or computer monitor, actually consists of tiny dors of
ed, bl, and green light. (See Figure 6.11.)

or in higher primates have
titer
nt pes ofcones) are responsible for color vison, investigators have studied the ab

found that Young was right Three diferent types of photoreceptors (th

Sorption characteristics of individual photoreceptors, determining the amount of
Tight firent waelengihs thai absorbed bythe photopigments, These chara
terne are controlled bythe particular open a photoreceptor contains diferent
“pins abr particular wavelengths more eas Figure 6.12 shows the absorption

‘haracteritic ofthe four pes of photoreceptors in he human retina: rods and the
(See Figure 6.12)

AUREL Le SANE TTY

182. BRETT carrer 6: von

eve heran of ih a lg y 16

Viol (m)

cept fs ot color sm

sr ablongmancom/eronte

The peak sensitivities ofthe three types of cones are ap-
proximately 120 um (bluesioet), 530 nm (green), ad 560
im (ellowgreen). The peak sensi of the shortaave-
Teng cone facially 40 nm in dhe intact eye becane the
Jens absorbs some ahortaelengh light, For convenience

Mens the short, median, and Jongavelengh cones are trad
Aionally called “blue” green” and red” cones, respectively
The retina contains approximately equal numbers of “re
gr and “green” cones but a much smaller number of "blue
‘ones (approximately $ percent ofthe toa,
(Genetic defects i color viion appear o result rom
8 anomaliesin one of more ofthe hree Wes of cones (Bost

{on 1979 Nathans etal, 1086 Wisner and
The is two Kinds of defective color vis
involve genes on the X chromosome: thus, because m

ave only one X chromosome, they are much more likely to
ave this disorder. (Females are likey to havea normal
on one oftheir X chromosomes which compensate fo
detective one.) People with protanopia (istcolor defect”)
confie rel and green, They se the world in shades of yok
low and blue: both red and green look yellowish to them,
Their visual acuity is normal which suggests tha ther eet

as do not lack Yed or “green” cones This fact, and their
Sensitivity to lights of different wavelengths, gests th
nes are filled ith “green” cone opin. Peuple wi deuteranopia
defect?) also confuse red and green and also have normal vial ac
ih. Their green” cones appear to he filled with “ed” cone opin

‘Tritanopia (thirelcolor defect") israre, affecting fewer tha Lin 10,000 people

This disorder involves fly gene that snot located onan X chromosome; there:
fore, tis equal prevent in males and females People with tritanopia have dif
‘ly wih hs of short wavelengts and se the wold in greens and eds To the

a clear blue shy is a ri Ther retinas lack “blue
‘cone, Because the retina comal dr abrence does not no-
‘icealy afec vial ai

pe 100)
described here

Air ved
seconds

1 green, and yellow looks pi

Retinal Ganglion Cells: Opponent Process Coding
At the level ofthe retinal ganglion cll the threecolor code gets translated ito

an opponent sem, Das (1968) and Gouras (196) found that these neurons re.

Spond specifically to pairs of primary colors, with red oppening green and blu op.

posing yellow. Thus, the reina contains two Kinds of colorsetive ganglion ells

fren and Jeliue Some colorsensahe ganglion

calls respond in a enieraurround Elan. For ex

à cel might be excited by red

the center of ther receptive

gargion els when a portan of

{he acepte Plá lama wth the or shown te cle
tating nee Wren porta y laminar he
amplement clr the cel ate ot hing ce

u Green on

ren

posite response in the sur
613) Oùber ganglion cel that receve input from cones
¿lo ot respond dferenialy to different wavelengths but

y encode relative brightnes inthe center and sur
vd. These cells serve black detectors”
The response characteristics of retinal ganglion cells
to Fight of ailferent wavelengths are obviowsly deter.
‘mined by the particular circuits that connect the three
pes of cones with the two spe of ganglion cell These
res move diferent pes of bipolar cells, amacrine

183. olor cain in the retina.) Re gt stimuting are" cone, wh causes eaten of re
‘een gungon cal.) Geen ght suman a “ren: con whieh cases bio 11
[een gon a Yeo ight stalin red and “rn: cons egal btt afin,
“Shue “Cons The simulation of ved and “gree” cons cases entation of ae tue
Sersion ca tei image cone wh cover ion ea love
‘retain ot cone nan bon ol Sarg ll or Say som othe

= ee Te sng

= urn ru =
Aa A AA AANA Mi
\ 0 W 01 0

¿YX ¿
oo 0) 00

Poseen gang col Redan ganen cot Yen. gurgion ca Yow org cr
A Lac srl low Sonata ogni te’
rn » ©

©

Figure 6.14 helps wo expan how particular hus are detected by the “ed”
green" and be cones and anse ito xi o imtico o the regen
and bone gon cells The gram doc noo th arnal neural
hich includes the retinal nens tat connect the cones wih ih angion cells The en
aros Figure O14 eer mere tote of ie tight Eling on rc ria. The | inte nenn
ook y Rick (1998) decret cual neural ica in onsderable deta, | acer nung mda pen
Detection and coding of pur ed green re light he eset to under | Powe cman eo
stand. For example, red light excites “red” cones, which causes the excitation of red | fed win “green” cone opin,
ren ganglion clk. (See Fi 6.40) Grcen ight exc gocen cones which | etocanot on awe
Caste nko of edge els (Se Fir &148) hu comun ico! | fee) Anar or ae
Jello light: Because the wavelength tat produces tne senso of ew incr | Reba Owen nth
ebenen ed tle cd and green concsabout | un anna
Ca, Vote ganglio cll ar exited by bah red and green canes 30 | “ed ca
ther rt offing increases, However eigen ganglion ces are excel y Ted | son nome pt) An
annie by gree so he ring ate dors mo change. The brain detecsanin- | rea do cr
‘essed fring rt frm the sxonsafjellomblveyangion els which e imepres | woneunansewe at
{yellow (Ss Piper 6.146) Be ight snp law na oe os
lion cells. (See Figure 6.14d.) AA:

184. See Animation 63, Com
QD screen can tore

singe an cet
comple! Anant
‘aes teen
eve os noes paper
Syren un
Ipercompen cl À ne

srr ablongmanconicronte

“The opponentcolor system employed bythe ganglio
not perce a res green or a blush yellow: An avon that signa red or gr
{oryellow or bie) can ether increase or decrease ts rate of ring: cam
atthe same ime. reia green wold have tobe signaled by a ga
ing lly and rapidly atthe same ime, which is ob imposible
‘Animation 6.1, Complementary Colors, cles
ge rom opponentprocens coding.

cellexplainswhy we can-

ten interesting phenomenon
mA

INTERIM SUMMARY

Coding of Visual Information in the Retina
Recordings ofthe electrical activity of single neurons in the retina indicate that each gan
‘aon cel receive information from photoreceptorsjust ne inthe fovea and many more
Inthe periphery The receptive fed of mst retinal ganglion cells consists of two concentric
‘ces, with the cel becoming excited when light falls in one region and becoming ini.
ine when e fall th other. Thi arrangement enhance he aby ofthe nerour tem
to detect contrasts in brightness ON cel are exce by ght inthe center and OF cesar
‘excited by ight inthe surround. ON cls detect ight objets against dark background OFF
alls dre dark objets agains light backgrounds

Colo vision ocur resul o information provided by thee types of cones, each of
which sensitive tight of a certain wavelength: long, medium, or short. The absorption
“characteris ofthe cones are determined by the particular opsin tat their photopigment
‘contains. Most forms of defective color vision appear 1 be cause by alterations in cone
pins. The “red cones of people with protanapa ar ile with green” cone opi, and
‘the “green” cones of people with deveranepia ar filed wth "red cone opsin The rt
nas of people with ttanopia appear o Lac “Due” cones.

Most olor sensitiv ganglion call repond in on opporing center surround fashion to
the pais of primary coles: re and green, and blue aná yla. The responses of thee eu.
1008 determined bythe tial uty that connects them wth the photoreceptors

THOUGNT QUESTION:
"iy isclo vision useful Br, some fs, and some primates hae fll tree cone color
‘sion Considering our own species, what othe benefits besides the ability to recognize
tips ft, which mentioned inthe previous section) might come from the evolution of
‘oor von?

The retinal ganglion cells encode information about the relative amount of
falling on the center and surround regions of thei receptive field and, in ma
cases about the wavelength of tha light, The striate cortex performs additional pro.
ing ofthis information, which then transits tothe viral sociation corte.

‘Anatomy of the Striate Cortex

The trate cortex consists of six principal layers (and several layers, arranged in
tans parallel o the surface. These layers contain the nucle of cell bodies and de
Artic trees that show up as bands of ight or dark sve ben
‘ed with a cellbody stain (See Figure 6.15)

185. Ana tt ntormatn: Roo te Sat ones MET
formation fom the parvocehlar nd 5 NM

-Ahotomicogaph fa mation at are miz
it anden aa corto Best wie mar ye
for Motte it contexon he opor sde ol the gy

In primates
‘magnocellular ayer ofthe dorsal tra genicuate mu
cleus enters the mide layer (ayer AC) of the arate cor
ex. From there it is relayed 0 the upper layers, when

ab by cisco of neurons. Axons bringing
ation from the Romiocelalar Layer form spas with
ncurons in ayer 3

we consider the arate cortex of one hemisphere
asa whole we imagine that we remove it and spread
Atout on a at surface oe find that it conan a map of
the contralateral lf ofthe vil ld, (Remember hat

cof the bran ces the opposite side ofthe vista

Field.) The map sitter approximately 25 percent of
the striate cortex à devoted to the ana of informa
tion from the fovea, which represents a small part ofthe
‘isl field. (The area ofthe vista Held seen by he fon
is approximately the size of a lange grape held at arm's
length)

pioneering studies of David Hubel and Torsten
d University during the 1960 began a
on inthe study ofthe ps
om (see Hubel and Wiesch, 1977,
Wiesel discovered that neurons in the visual cortex did
not simply respond to spots of ight: they selectively responded so specific rates of
the visual world. That, he neural ereury within the val cortex combine ln
Formation from several sources (for exa

pe, rom axons carrying infor

«cies from several different ganglion cel) in such a ayas o detect features hat

are larger than the receptive fel of a ingle ganglion cll The foloing subsccions

describe the vial characteristics that researchers have studied so far orientation
sement, spatial frequency retinal disparity and color

Orientation and Movement

Most neuronsin the state cortex are sensitive o entation. Th

¡fa nes po
sitioned inthe cell's receptive fel and rotated around it center, the cell wil re
Spon only when

neurons respond best 1. vertical ine, some toa horizontal inc, and some toa ine
‘oriented somewhere in between. Figure 6.16 shows he responses fa neuron in the
state cortex when fines were presented at various orientations As ou can sce ih
‘neuron responded best when a vertical ine was presented in is recepie fc. (See

Tne fn a particular position particular oriemation. Some

Figure 6.16)

‘Some orientationsemstve neurons have receptive fields organized in an oppo
nent fashion, Hub and Wiesel referred to them as simple cells For example. ine
fa particular orientation (say, a dark 45 ine against a white background) might

sc ell if placed in the center of the receptive Fl ut inbibi it if moved way
from the center (See Figure 6.17) Another typeof neuron, which he reearchers
referred 0 as complex cell, also responded hes toa line of « particular orienta
Lion but di mot show an inhibitory surround: hat, continued to respond while
the line was mee within the receptive fil complex cells increased
their rate of fring when the fine was moved perpendicular to lis angle of orienta
tion often onbyin one direcion. Thy, these ako served ax movement de:
tector Inaddiion, complex cll responded equally well white nes against black
background and black nes again white backgrounds (See Figure 6176) Final
Inypercomplex cells responded o Ines of a particular orientation but had an
ibi region atthe end (or end) ofthe fines, which meant that dhe cells detected
the location of sof lines ota particular orientation, (See Figure 6176)

Figure 6.16

Strate cortex vl become ative
en neo ni

Bd

186. ‘pata trequeney ee
retinal pay Thea
roche aise (co) ob

apor characteris of nero o art
(2) Compeccel 1 Hypercomper ca

22.0

= „= Corine ect y atmen um
o

oo

et Mr

O

he primary score (a) Simple ct.

Spatial Frequency

y early suis by Hubel and Wiesel suggested th
mary ual convex detected lines

win the pr
d edge, subsequent research found that they ac
{ually responded best to sinewave gratings (De Valois, bree, and Thorel, 1978).
Figur 6.18 compares sinewave grating witha more familiar square-wave grating, A
square save grating consists of ample set of rectangular bars that ary in brightness
‘he brightness along he length o line perpen
ie (quarcaane) fasion, (Se Figure 6.180.) A sinewave gating looks ike a series
fanfare parallel bars. Along ans Tine perpendicular to the long ais ofthe
fring the brighinen varies according to sine ave funcion. (See Figure 6.18
A sine grating esate bys patil frequency. We are accustomed tthe
expresion of frequencies (or example, of sound waves or radio waves in terms of
me or distance (sch a le per second or esper meter). But cate the in
age fa simulus on the retina varies in ize according to how cose iso the eye he
Sal angles generally used instead ofthe physical distance between adjacent ces.
Tis the spatial frequency ofa sinewave gratis variation in righiness messed
in les per degree of tal angle Soc Figure 6.19)
‘Most neon in the striate cortex respond best when

SAE ei pepe pert of he sel eh Dah

Part gangs) aus ive gang (See grating, the point of having neural circuits that anale spatial

pleated mae

Lit you are interested, yo can const De Valois and De
Valois, 1988) Consider the types of information provide
"oy high and lw spatial frequencies. Small object, details
within lange object, and lange objet ith sharp edges
Provide signal ich in igh frequencies whereas lange ar
‘as of ight and dark are represented by low frequencis

nage dat diet high requency formation
Tooks fy and out of focus, ike the image sen bya near

O 0

e. so vil give a simplified one here

sighted person who is not wearing corrective lenses, This

ite sl provides much information about form ane

187. aon hat comand inde ai penis. 1 onset ann er ger
Frequency in reinen been the ure waves with the pert toe
(fiel 10 perceive, (As we wll sc, Ihe more primitive Magna te sing wes wit te apa the
cellar tem prenides lovefrequency information) amas when the maver re ser opte

sremoved, the shapevof images are very

Retinal Disparity

We perceive depth by
thar can be detected monocular by one eye alone, For came
ple, perspective, relate retinal size, loss of deal through the
effects of atmospheric haze, and relative apparent monement of

Fetal images ae move our heasall contribute depth per
5 pp

and donot require binocular vision, However, inox
the

lar sion provides a id perception of depth thro
ix Myo have med a

proces of stereoscopic vision, or sm
Mereoscope (mich as à View have scen a
dimensional movie, you know what I mean. Srcopsi spa
ticularly important in the vial guidance of fine menement of
Abe hands and fingers such ase we when we thea a needle

ost neuronsin e strate cortex are Ainrular as hey

respond oval aimulaion ol eter eye. Many ofthese bine

ar cell especially those found in a layer that receives informatio

ar sem, hive response patterns that appear o contrite to the perception of
‘depth (Poggi and Poggio, 1984). mow caes the ells respond mos gory
‘wen each eye ss a mulas in lightly dja location, That the neurons re.
spond to retinal disparo imu that produces images on light diferent parts
‘Of the retin of each ee. This exacl the information that needed for repris,
‘each eye sex a thrcedimenonal scene sight diferen, and the presence srt
hal pari indicates dllerencesin the distance of objets from the observe,

Color

In the striate corte, information from colorsensive ganglion

cell transit through the parvocellular and koniocellular MNFIQUrE6 20

layers of the dorsal lateral geniculate nucleus 10 special cell ghotomivographo sie tough he rimar vu
¡groupe together in ytochrome oxidase (CO) blobs. CO blotn cer ea mac monto, poe De soe, The
were discovered ty Wong Riley (178), who found thats or aah spot re the Bobs, colored by aston fr ocre
Stochrome oxide, an emm thats present in mitochondria, de
showed patchy distribution. Subsequent resarch with he si
(Horton and Hubc, 1980; Humphrey and Henrickson, 1980)
presence of polkadotpatern of dak columns ex:
{ening thong yes 2 and Sand (more (aim) layers Band.
The columns are cal in eros section, approximately 150 » 200
min diameter and spaced a Ban itera Fitzpatrick Woh,
and Diamond, 188%; Livingston and Hubel, 1987
igure 620 shows photomicrograph of a ic through a
imacaque monkey al cortex that ha en flattened out ad
«or the mitochondrial enzyme, You can clearly se the
CO blobs within the state cortex. Because the cureature of
cortex prevents i rom being perfects Nattened, some of
ise is missing in the center ofthe ice, (See Fire 6.20)
Uni recent researchers believed that the parvocellular
sem transite all information pertaining to color to the
striate cortex. However, it now appca
Siem receives information onl Io

that the parsocelllar 509 7 37.3013 Coppa 89 Sosy fe
red" and green” cones; tore

188. RER cartes 6: vison worm ablongman comicaonse

divonal information rom “blue” cones transmite through the koniocela
tem (Hendry and Yoshioka 1994 Martin etal, 1907; Komatsu, 1008)

To sunmarir, neurons in de conex respond to seal differ
tures of a inal stim including orientation, monement, spatial frequency re
tal dipar and color Now let us uaa our attention to the way disinformation is
‘organized within the sate corte.

Modular Organization of the Striate Cortex

caer dominance Meet | Moat

vesigators eleve ta the brains organized in modules, which probably
in sie from a hundred thousand to few milion neurons. Each module re
‘eines information from other modales, performs some ealelations, and then
pases the results to other modules, In recent years investigators have Deen
the characterise of the modales tht are found in he ial cortex (De Valois and
De Walon, 1986; Eivingutone and Habe, 198).
The write coriex divided ino approximately 2500 modules, ach approxi
imate 0.30.7 mn and containing approximately 150.00 neurons The neu
ye devote o the anal of various fates contained in om
Stal portion ofthe visual el Clic hese mod
[entire al ck, he individual modules serving ike the es in a mos
parvocellua.koniocelular and magnocellular Ever of
ral geniculate nucleus s receive by diferent sublayers the strate cortex: The par
Sorell input receive by yer CB, the magnocellatr input freche by Layer
AC und the konocellula input rec by layer 3.
The modales actual const ol two segments cach
AGR rounding CO blab. Neurons located within the las
‘ne ofthe moles of he primary ala have a special function: They are sensitive o color and o.
Tow spatial frequencics ut are relatively insensitive o.
cristal features Outside the CO blob, neurons she
tear, and binocular disparut mont do not re
spond vo color (vngatone and He, 1984; Born and
Toovel 1991 Edwards Purpura, and Kaplan, 1945), Each
half of the module receive input fom ony one exe but
the ciety within the module com
Ion from both eyes which means that
ons are bin Depending on thie locations within
the module, neurons receive Sarying percentages on.
put fom each ofthe eves
Ite record from neurons anywhere win a single
modulo, we wl find that al of her reeves ner
tap. Ths al the neurons in a module analyze information
fromthe sme region of the vs eld Furthermore we
insert a microelectrode straight down into an erhob re
sion of the write cortex (hats in a location in a mode
tute one ofthe CO bbs) we wl ind both simple and
Complex cells, but all of the osienaionsensiive el will
entation. In addiion. hey
willl share the same ocular dominanee—tha 5, the
Tae percentage of input from each of the eyes. If we
none bur electrode around the module, we wl ind that
these wo charactersie-ovienaton sent and ocu
Jar dominance—vary sytematcally and are arranged a
Fight angles to ach other (See Figure 621.)
How this organization?
edward, Purpura, and Kaplan (1995) Found that new

Layer ot te sit corer

189. Ana! Vs toman: leo te Van Acton ones CE

rons within the CO blobs responded to Low spat fi
cios but were sense wo small differences in brightness
Outside he babs, semi 10

the distance from the cen
‘quencies were associated with greater distances, (See Figure
(622) However ncurons outside the blabewere les sensitive
to contra; the diflerence between the bright and dark a
casof the sinewave gating had o be greater for these new
tons than for neurons within the blobs,

INTERIM SUMMARY

Analysis of Visual Information:
Role of the Striate Cortex

‘The sit cortex const of se yer and several sublayers. Visual
Information received rom the magnocellular, parvocelular. and
Konicelllar ayers of the dorsal lateral geniculate mace. The
magnocelilr sistem is more primitive color ná nd sont
o movement depth, and small iferencein brightness. The por.
vocelar system i more recent, cola senti (Feceving info.
mation from “red” aná “geen” cones) and able o dsciminate
finer deals. The konioclulr system provides additional infor-
Imation about color received rom "Due" cones.

‘optimal sata equency ol neronsin site cones
‘incon af ne tance ol nero rm th center of he
‘nae tormes ll

Mo 2%» ado
Dstane tom center CO Bo (m)

a onto PR En
An 1.1. a mn

The site corte organized into modules, ach suround-
ing a pair of CO blobs, wich ar revealed by a stan for chrome oxidase an enzyme
found in mitochondra, Each hat of» module receives information from one eye but be
(aus information share, met ofthe neuron respond o input to bath eyes, The ne
onsi the CO bibs are sensitive to color and 1 lw requeny sine ave ratings where
‘those between the bibs are sensitive 10 sine ave ratings o higher spatial requencies,
tentation, retinal parity, and movement

THOUGHT QUESTION

Look at the cen in ron of you and ty to imagine how its features are encoded by new
‘ons in your site cortex. Ty to picture how the objets you see can e specific by an
Anal of orintaton, spatial frequency texture, and coor

state cortex sees on art ofthe visual fc. Ts,
for us to perceive objects from these indi
‘ual modules must be combined, That combination takes place inthe visual ao.

tia con ent

Two Streams of Visual Analysis

Visual information received from the strate cortex i analyzed in the ssl oc
y cortex. Neuron inthe rate cortex send axons 1 the extrasriat cortex, the
region of the visual association cortex that surrounds the state cortex (Zeki and

190. BETZ Haren 6: vison ov ablongman consciente

Shipp, 1988). The primate extrait

tr noce independent maps the visual fick. Each region le specialized containing
Feurons that respond toa particular feature of val information, such as orienta
tion, movement, spatial frequency retinal disparity, or color So far, invcsigatons

the visual cortex ofthe

Ihave identified twenty Ive divine regions and subregions
rhesus monkey. These regions ar arranged hierarchically, be vith the st
ind Felleman Mo

ate cortex (Van Essen, Anderson information
ass up the hierar each regó

feat it im the erarch, analyzes the information,

texof the human brain. The views ofthe brain in Figures 6.29a and 623b are nearly
and 6.234 show “inflated” cortical surfaces em

The hidden regions are show in dark gras, and regions that are normally visible

Uae surfaces of gyri ae shove in ight gra. Figure 6.2%e shows an unroling of the
tical surface cual to the doted redline and green lines in Figure 62% and
(See Figure 623)

a“ ofthe outputs often called VI, because itis the it
: nacen to VI. À ways diverge. On the bass of thelr own re

ce | arch and a revi igericier and Mishkin (1982) concluded

angen andthe ventral stream, Subsequent anatomical studies ave confirme ths conc

se Son (Balzer Ungerteder and Desimone, 1991), Some of the outputs of area V2 con

‘apt eve) Anurag of tec ac caudal ote Sted rene and green
ne own ton (84

191. ie of he Vis con Core AFF
rd tonal a series o regions that consi IRSA

aberseacend ino segons ofthe cor A
‘The ventral stream ecogizes wht an object né en om e ee e wo seams ot

recognizes ut the object isk

Anais ot Valine

is and the dora area

cited. See Figure 624) ora Steam
As we athe parvocellular, hontocellular, and Patien) 7
"oca stems pride diferent kinds of informe ‘arta ioe ‘rate conor

‘The magnocellular gem is found in all mammals
ar and koniocellulr stem are Da tri

{ound onlin primates, These stems receive information
from diferent pes of ganglion cell, which are con
nected to diferent types of bipolar cells and photorecep-
tors, Only the cl the parvocellular and konioclluar
‘te receive Information about wavelength from cone;
stems ana information o olor.
vocelllar em als shove high spatial rex
om temporal solution; hat ey are able
to detect very fine details, but ther response is slow and
prolonged. The Koniocelular stem, which receives in
Formation only from “blue” cones, which are much les
‘numerous than red and "green" cone, doesnot provide
mation about ine details contrat, neurons inthe

Image gte are car ind They ae woe to EA

detect Fine deal, but they can detect smaller contrats ieee va
‘between light and dark. They are alo expecially sense socio cor Vos Sveam
1 moxemem. (See Table 62)

Perception of Color

As we saw cari ne
‘or Like the

CO blots in the striate cortex respond to co
‘the retina (and the parvocelllar and Rincer
sal lateral geniculate nucleus), these neurons respond in oppor
information Is analyzed bythe regions of the vial association

192. eas
‘Sram corto
roms y tp

‘wor ablongman conversan

Studies with Laboratory Animals
Tithe money brain, neurons in the CO blobs send information about color
aspect subarea o the exraurite cortex, Zeki (1980) found that neurons i this
Subarca (called VA also respond secte} to colors, ut their response character
ines are much more complex. Unlike the neurons we have encountered so a. these
neurons respond 10 a variety of war ot just those that correspond to Fed
‘green, yellow, and lu
The appearance ofthe colors of objects remains much the same whether we ob
der ar der an onereat sb. at noon on a cloudless ca
non known a color constan. Our sal system doce not simple
a he ight elected by object in each part of
ek: instead, compensates or the source ofthe light Wash etal (1995)
image wo area Vl disrupts color constanc: The investigators found that
although monkeys could sil discriminate between
been damaged, their performance was impaired when th
‘mination was changed. But the fat thatthe monkeys could sil perform a color di.
‘mination task under constant ilumination means that some region besides ara.
VA mus be involved in color sion. Animation 6.2, Color Cnstany lustre he ch
{ects of the color of oxerall lomunation on color perception
"Astudy by Fle, alla, and Comey (1995) appear to have found he region
responsible for color sion in the monkey bran: area TEO, a portion ofthe
temporal cortex just anterior to area VA. The ivesigators estropee area TEO,
ing arca VA intact and observed severe impairment in color discrimination, Th
monkeys had mo dieu discriminating hades of gra, othe deficit on this unkap-
o be restricted to color perception (As we il ac ater, Lions of the nf
poral cortex also disrupt the ab co pereche and recognize objects)

Studi

with Humans
Lesions of restricted region of the human exrastite cortex in the medial oe
pital lobe can cause os of color vison without disruption of vial cui The pa
tients describe their son as resembling a blackandwhit film. (Damasio etal
1980; Kennard etl, 1905). The condition is known as achromatopsia Cision wil
cout color) A he brain damage is uniera, people wil lose color von in only hal
‘fhe visual field, In addon. they cannot even imagine colors or remember the co!
‘rs of objets they sax before their bran damage occurred,

A functional MRI study by Hadfikhan et al (1908) found a colorsen
inc inferior temporal cortex, in a potion corresponding to TEO in the monkey's
‘cortex, which they called area VS. Indeed, lesions that case achromatopsia damage
Var oer brain regions that provide input 10 VS. (Refer 0 Figure 6.23)

“Of couse, perception of color iles in cf, The function of our ability 10
perceive difieren colors sto help us perceive different objects in our environment
Therefore, to perceive and understand what i front of ws, we must hase infor
‘mation about color combined with ater forms of information. Some people with

y damage lose the ability to perceive shapes but can il perceive colors For ex-
ample, Zeki etal. (1900) described a patient who could ently colors bu as on
‘rae bind. Patent PB. reeeved an electrical shock that caused both cardiac and
Fespiraory ares, He was revived, but ive dame

ive region

period of anoxia caused ex

ge to hs eure comes, Ava esa he ln ll form perception However, he

‘onl ently the colors of objects presented on video mon

Analysis of Form

“The analysis of form by the visual cortex bogins wi
that are sensitive to orientation and spatial frequency. These neurons send it
Formation tothe extraite cortex, whieh consi of several subregions. These sti

193. Ara Informa: leo the Ves Asco Coe METRE

send it along e UEG LE

Ares fi comento shes mony br.

information
poral neocortex.

regions analyze u

Studies with Laboratory Animals

In primates, the recognition of vital pate
cation of particular objects take place in the infe-
for temporal cortex, located on the ventral part of the
temporal lobe, This region of visual asociaron cortex s
located atthe end of the ventral stream, I is here that
analyses of form and color ae put together and percep
tions of Ihreedimensional objects and backgrounds are
achieved. Damage 0 the inferior temporal cortex cases
Severe defichs in visual discriminacion (Mishkin, 1966:
Gross, 1973; Dean, 1976) (See Figure 6.25)
Neurons in the inferior temporal cortex respond best
to threedimensional objects (or photographs of them).
hey respond poor to sin such as spas ines
er ainewave gr we to respond
‘cen when these stimuli are moved toa diferent location,
fare changed in size, are placed against a different back xo %
ground, oF are partially cluded by another object Rolls
nd Baylis, 1986; Koes, Vogels and Orban, 1995), Thus, es amp
they appear to participate inthe recognition of objets
rather than the analyst of specifi Features, ee een
Like other regions ofthe sisal corte, the inferior
temporal cortex arranged in columns Neurons in adj
‘ent regions tually respond vo ight diferent versions ofthe same stimuli, For exe
ample, several studies (for example, Desimone e al, 1981) have Fond newton
the temporal lobe of the rhesus monkey that are specifically excited by the sight of
another fice—either tha of another monkey or that of human. Some ofthese neu
ronerespond ofllface views, and others respondo profiles, Most ofthese facer
lear located in arca TE and inthe cortex that lies the anterior Bank af the
or temporal ulcu (arca STS). (See For 625),

Studies with Humans

Damage to the human visual asocition cortex can cause a category of deficits
‘know as visual agnosia. Agnes (aire to Know”) refer to an inability to perceivo
or identify a stimulus by means of a particular sensory modality, even (hou is
‘etal can be detected by means ofthat modality andthe person retains rela
normal intellectual capacity. Apt visual aguosias ae failures in high evel
perception, whereas aviat visual agnosasate disconnection between these per.
‘eptionsand verbal ystems, The disinction willbe described

rast le

section. on conne on vee
Apperceptive Visual Agnes. People with apperceptive visual agnosia cannot | vil agnosia ne

dent common objets b sight, even though they mas have relaivch normalisal | Deets morron a he

acuity. However, they normally can sl read--even small Saver ars eas

mit to hold an object that they cannot recognize vial, hey can normally | Te" Sri

recognize it right away by touch and say what tis This abi demonstrates sppeceptve vus agnosis

fave no Tot her memory fr the abject or have simply Yorgten how so sy lo | epica o
— BEIDEN BEMESSEN Sr a

pea von hngne
Are Paes Spee? common emp of appecep vial agnosia lo | mame mh

prosopagnosia, inability to recognize particular faces (pom is Greek or ace”). | y pop argo per
Thats, patents with this disorder can recogniz that they are looking at a fac, but | ces

194. tuto te an Ant
Coin a ete

sw ablongmancon/caronée

they cannot say whose face it even iit belongs o a relative or close friend. They
sce jes cam, a noxe, a mouth—but cannot recognize the particular configuration
‘Of these features that identifies an individual fee. They sl remember who these
people are and will all recognire them when they hear thei vice. As one par
tient ak, have rouble recognizing people from just faces alone. 1 Look at ther
hair color, sn to ther voices... se elothing voice, and hair. ry to asociate
something wih a person one way or another... hat they wea, hw their hai is
sworn” (Busbaum, Glower, and Cote, 1999, p.49).
investigators believe hat facial recognition is mediated by special circuits
in the brain that are devoted to the specific analysis of facial features, The most re
‘ent evidence suggests that Faces are ined recognize by special circus in the vi
sal awociation corte, but that these circuit are not genetically programmed ana
Tacerecognizing device” Instead, they develop through experience, and can be
cd for learning o recognie other spero! vs sim
recognize particular perso
bie difiere
al the other Features that distinguish one
imaged people and functional imaging stds suggest that these pe
‘al facerecogoizing circuits are found in he fusiform face are, a region of vial
sociation cortex located in the extrastiate cortex at the base ofthe rain. (See
Kanwishen MeDermot,
Is more important than the let (See Figure 626)
Perhaps the strangest piece of evidence fora special facerecogniton region
comes rom report by Moncontch, Winocur and Behrman (1997), ho studied
“vial agnoni for objecis bu no for faces. For example, he recognized.

AFIGUTEG 26 sncrpuponc oecerecogiion crete were dam

pa abe an the base of he ban

inthe entation te ae bu

sitorm face region was not.
So there seems to be a special region devoted to
recognition of faces But must we conclude that the de
‘lopment ofthis region is a result of natural selection?
Several Kinds of evidence sige that the answer in no-—
thatthe facerecogniton ccs develop asa rel ofthe
extensie experience we have seing peoples aces Be.
‘cause of ths experien, we:

faces, What about people ‘experts at
recognising other spes of objects? appears that eco
nition of speciic complex stimuli by expert, 00, le di
‘pte by lesions that cause prosopagnosi:inabiliy ola
Farmer o recognize his coms, inability ofa bird experto.
recognize ter

ser to recognize
plate (Bornsc .
Damasio, and Van Hocsen, 1082)

. 1960: Damasio,

Gauthier et al (2000)
foun bird or car experts (but nat nonexpers)
viewed pictures of birds or ar, he Form ace area was
acikated. Another study (Gauthier etal, 1999) found
that when people had spent Tong time becoming fai
ar with computer generated objects they called “rec.
bles” viewing the grechles activated the fusiform face
area (See Figure 628)

Aa me wil se in Chapt
order fa

people with autistic dis
oral social relationships with

196. 100 cuarren 6: von ov ablongman cometen

PT ER SE DT

Arte val agro) Medel) Patient cent temp to copy mode)
Pan untl temp 0m witha equ “aan an ant”

LL

rm aa. nm ml GR EY
AE don ee es 8,

perceive the shape ofthe anchor, However. he did not mengnisechher the sample or
the copy that he ad jt raw as being an anchor: When asked on another occ
¡ion to draw a piture ofan anchor from memory (not from a picture), he could not
00. Even though he conld eopya rel image ofan anchor, ie word anchor filed
to produce a mental image of one. (See Figure 629) When asked on yt another oc

o define ancho be sad, a brake for ships "so we can conclude that he ket

that the word

Associative vis

sonia appears to involve a deficit in the bio transfer in
formation between the ial association cortex and brain mechanisms involved in
language. That is the person pereches the object wel enough to dra, ut his or
her verbal mechaniane do not receive dhe necessary information to produce the ap
propriate word or to think abou what the object In the prologue to thi
1 described Me M. a man who was unable o recognize u picture of co u
observed himself making milking movements wiih his hands, We might speculate
ereepial mechanisms inthe ial association cortex were rclathely nor
at connections between these mechanisms and the pose nisms of
the left hemisphere were darupted. However, the connections between the percep
tual mechanisms andthe motor mechanisms of the frontal lobe were spared per.
iting him to make appropriate hen looking at some pictures

Perception of Movement

We need to know not only what things ae, ut also where they are and where they
are going. Without the ability to perce the direction and vloity of monement of
‘Objects we would have no way to predic where they wil be. We would be unable to

them (or avoid letting hem catch us), This section examines the perception
‘of movement he final section examines the perception of location

Studies with Laboratory Animals

One ofthe regions ofthe extrastiatecortex—area VS, also known as arca MT
or medial emporal—contans neurone that respond to moxement. Damage o this
region severely drupe a monkeys ability to percciv moving mul (Siegel and
Andersen, 1985). Area V3 receive input direc rom the miagnocellular sate va

197. ‘tennis play must be able to perce the eco and ic of eon alto
roe rd nece wh hat Prapio moto dpi

the strate cortex and from several regions of the extrsrate come also receives
input From the superior colliculus

À region adjacent to rca V3 (sometimes ale Va but more often referred o
as MSF, for mea! superior omporal) receives information about movement from VS
and performs further ab. MST neurone respond o complex paternsof move
‘ment, inching radial, circula, and spiral motion (ce Vaina, 1988, ora review),
‘One important function of this egion-—in particular, the donalateal MST, or
MSTd—appears to be analysis of opt
‘ras objects in our environment move in relation tous, the sizes, shapes, and loca

tions of environmental features on our retinas change. Imagine the image scen by à
‘ico camera as you walk along a street, pong the lens of the camera straight in
front of you, Suppose your path wl pass jus to he right ofa mailbox. The image of
the mailbox wil slowly get tanger: Final, you pasch, will ert he lt and ie
"appear Points onthe slewalk wll mone downward and branches of tres hat you
Das er wil ene up. al of he eae cme of he al ie

thw fit you are approaching difevent tem in font Of you, and whether you wi
pss tothe left or right (or under or over) these ems. The pont toward whieh yo
are moring docs nat move. but all other point inthe vial scene move away rom
it Therefore, ths point ls called the euler of expansion, I you keep moving in the
same direction, you vil eventually bump into an object that es atthe center of ex
pansion We can also use optic flow io determine whether an object approaching us
Fal hi us or pas by. Neurons in MS

Mo and disruption of the activity of MSTA ncurons disrups monkey abit to
perceive direction of heading (Bradley et al, 1996 Brien and van Weel, 199),

Studies with Humans

Bilateral damage to parts of the via sociation cortex ofthe human brain can
produce an inabilay o perecive monement—alónctopaa. For example, Zl eta.
(1901) reported the ase of a woman wih lateral lesions fe lateral occipital cor

ex and area VB
Patient LM. had an alo
Lo ro street without trai ight became she could ot judge the speed at which

tons 0

movement perception, She was unable

into by to pro

198. cars were moning. Although she could perceive moxements, she found moving
‘ery unpleasant to look at. For example, while talking wth another perso
vod looking atthe person's month because she Found is mosements very die
tubing, When the inves
ein the laboratory she sid, Fra the target iscompleich at rest Then i
Jimps upwards and downvards”(p. 2244). She wae able
‘constantly changing its postion, bit she was unaware of any sensacion of movement
Ay we sarin the previous subsecion, neuronsin arca MST of the n
respond to optic flow. an important source of information about the direction in
‘nll the animal is heading. À functional imaging study by Peseta (2001)
that dhe same region Became ative when subjects jciged their heading while
sewing display showing opie low. In addon, Vana and her colleagues (Jornaes
‘tal, 1097; Vana, 1998) found that people with lesions that included ths region
‘were able to perceive motion but could wot perceive heading from optic flow. (A
mation 6.3, Motion free rates monementrelated phenomena)
Perception of movement can even help us perceive thtcedimensonalforms—
meron known as form from motion Johanson (1978) demonstrated jus how
formation we can dere from mene

asked her o try to detect movements of val tar

ven

onkey brain

He dresed actors in black and a
Tight to several points on Aci bodies, such as their rss, bons
shoulders, hips knees, and feet, He made movies ofthe actors in a darkened room
hill hey were performing various blasons, such as walking. running, jumping
limping, doing puatreps, and dancing wih u partner «ho was alo equipped vi
Tights Even though observers eho wate the fis coul ec nb a pattern of mos
ing ight against a dark background, they coul readily perccive the pater a be
Tonging to a mening human and could identi the behavior the actor was
performing. Subnequent studies (Kovlowski and Cutting, 1977 Barclay, Cating, amd

ki, 1978) showed that people could even tell, wich reasonable accuracy, the

sexof the actor wearing the lights, The cues appeared o be supplied by the relative
amounts of mosement ofthe shoulder and ips the person walked
À functional imaging study by Grossman e al, (2000) Found that when people
ewe ideo that showed form from motion, small region on the ventral Bank of
the posterior end ofthe superior temporal cu became active, More acthiy ws
‘cen in the right hemisphere, whether the images were
presented 1 the let or right vial Rl. (or a demon
Station of this phenomenon, sce Animation 6, Form

the potros enol he super tempor cs pac the

from Motion) Grossman and Blake (2001) found that is
region became active even when people imagined that
they were wating points of Hight representing &
fom motion. (See Figure 630)

Perception of Spatial Location

tare af the extract cortex

rior temporal cortex. the region
in which object perception appears 10 take place In ad
dion, dive subareas of the extrasrite cortex —thowe

information to the i

involved with color orientation, and movement—send
information through arca V3 to the parietal cote, (Re
{er to Figure 6.25) The parcial lobe moe in spatial
vere, iit ee onto at
event sisal input. Damage tothe parietal lobes di.
‘ups performance on à variety of tks that require
percciving and remembering the locations of objects
(Ungerteder and Mishkin, 1982) and funcional image

Studies have revealed increased activation ofthe dor

199. ‘primers ndice caen of ane ld.) An em) proce y e flowing
ne mapnan cocinada med Hoi NR

Front N
sa rea when people perform tisk that require them o remember the pata lo
Cation of visual inl (Han et a, 1994),

‘functional imaging study by Melle tal (1906) showed that the dora stream

ring to verbal it ne an asernbly
‘of cubeshaped block, put together one by one. For example the asembly in Figure
581 begins with the block shown in blue, The second block goes tothe right ofthe
fin, the thie goes below the second, he forth goes below the ir, and won. (See
Figure 6310) Functional MRI images that were taken while the subjects were
structing the mental images of these object (ound increased aıhiy in a bi
‘ccipitoparictalfrontal network that included the superior extrastiate
‘occipital oe, inferior pare ral premotor cortex

uctions The investigators asked people oi

Ati as als sen in
imagining the conaruc
(where spatial perception ta frontal lbes (where pla
mens takes place). The imolrement of the Yea the ig
‘ay reflect the people's recognition of the imaginary shape dey had consructed.

INTERIM SUMMARY

‘Analysis of Visual Information:

Role of the Visual Association Cortex

‘Te vial cortex cons of the state cote, the extrait corey, and the vil sch
rent fe different subregions of the wa corte aranged in a irarchcal fasion. The

200. or ablongman conversan

Colorsenstve ells in the CO blobs in the svat certe send information areas V4 and VE
ofthe exrasviate cortex. Damage tothe ara Va abolishes color constancy (ncurte per
(option of oor under iffren lighting conditions, and damage to ara VE causes co:
matos, los of color vin but not of form perception, A condition opposite to
Sohromatopia can ao be sen: A patient with extensive damage tothe extrestrat cortex
vs functionally lind but could sul recognie colors. His brain damage apparent} de
Soyed regions ofthe vival association cortex that ae responsible fr fm perception but
not tote fr color perception,

‘The sual orton organize into two steams The ventral stream, which end with the
Inferior temporal cortex, involved wth perception of object Lion oft region dirupt
sal object perception. As, single neurons inthe interior temporal cortex respond best
to comple stimul and continue todo so even the objets moved to a diferent cation,
‘changed in size, placed against a diferent background, or parti hidden. The dorsal
stream, which ends with the posterior parietal corte, volved with perception spatial
location and movement

Functional imaging studies indicate that specific regions ofthe cortex re involved in
perception o form, movement, and colo and these studies re enabling sto discover the
Corespondences between th anatomy ofthe human visual stem and tat of abortory
“animals Studies of humans who have utined damage to te sa! moin core have
‘Secovered two base forms of vun agnosia, Apperceptive visual agnosia involves fit
in perceiving the shapes of objets, even though fine details can often be detected
Prosopagnosia—falure to recognize faces “appears to be cause damage tothe uf
{ace are, a region on the medal surface lt right octal cortex The development of
his egin appears to bea result of extensive experienc looking a faces espere with
‘other comple stimuli such as cows, Dir, cas, oF even artical ratures (rele) causes
‘the development o circuits devoted tthe perception ofthese stimula wl The Alm
{ace region fais to develo in people with atm, presumably because of insffien mot
‘ation o Become expert insecognzng other people faces

"The second basic orm of vial agro, asociativo visual agnosia, caracteied by
‘elavely good obje perception Gown by the fact that the patients can copy drawings
‘objects but the inability to recognize whats perceived. This order probably caved by
‘damage to axons that connect the visual asocation cortex with regions of the brain that
ar importan fo verbalzaton and thinkin in words. Some patients with Wis disorder an
describe or mime actions appropriate tothe objects they see but cannot recognize

Damage to area VS (ao called area MT) disupts an animals aby to perceive move-
‘ment, and damage tothe posterior parietal cortex erupts perception o the spatial loa
tion of object. Damage tothe human visal association cortex corresponding to ara VS
rps perception of movement producing à dorer known a akinetopl, In addition.
{funcional imaging studies show tht perception of moving Small acte th region. In
both monkeys and humans ares MST, a region o extasat cortex that receives infor
‘mation fom area VS, appears tobe specialize for perceiving opti low, one ofthe cots we
‘eto perceive the drectionin which we are heading. The ability to perceive form rom mo:
tion—recogniton of complex movements of peopl indicated by ight attached to parts of
‘their body probabiy related tothe ability to recognize people by the way they walk This
ability apparent depends on à region of cerebral cortex on te venta bank ofthe poste:
ior end ofthe superior temporal ulus.

THOUGHT QUESTIONS

Some psychologists ae interested in “top-down” processes in vial perception —
thats the effets of coment on perceiving ambiguous stimuli For example if you
are na dimly lighted kitchen and se a shape that could be either a oa of bread or
county mbox, you willbe more likely to perceive the object ta loa of bread.
‘Wherein he brain might contextual Information affect perception?

‘neurologist end once told me about a patient he saw who had such severe
prosopagrosia that he could not even recognize his wie by ight. One day while

201. Aras! vst infmston leo te Vu Acton Core ME

ny fend was examining the patient, the patents wife entered the hospital oom.
Can you tel me who that? he aked, wanting to determine whether the pa
tient Symptoms had improved. "1 do’ now” he sad “butt certainly ant be my
dear Lucie” Butt was. What typeof prosepagnosia di the man have, apperceptive
a associative? How might we explain his Behavior?

Case Studies
The dscasion of M Min he prologue matins semves asthe basis forthe bi stea could be that behavior X's im
es an se about research at Iso ls and remember) pares by damage to mode A and be.
‘woul ie to addres he e of mak Wet toundertandhow the hair V impares by domage to mod.
Ing general rom the stay ofan bain wo, e harto know what tele Band jo happens that modules A
Indra potent Some exce indhidal module do.Aparcuur apd wer both damaged y e bain
fave pue hat beau no two peo- modules not response for beh lion. However, we can conde that if
ls ak, ve cannot make general arisen, performs ane of the mary a bain lesion cuss sof Behavior X
[extent m ade ind! Me. functions that ae necesa for aseo! but otf Behav the the ane
They ay tata infrenes an be bain For example, are y an performed bythe damaged mad-
‘made ony from tudes tatimoe _ ingihseplogue.lam wing modules are not require to perform bea
Grau of people so at main at perform funcio relate to por. ler. The tay ange patient
rence canbe accounted for atts tre and banc, ote conolofeye rt ut mate conca.
al crim vale? Movement to memories rested tothe The condon might seem rather
The careful detalednesigntan ot opi om wring abou to memories of modest but an aduce our under
‘he bi and buts sauge Engin and the spelings to ang ofthe types of bain funcions
perioncang a cate study Inmo — conta finger movements. wel, ivoved in parular behavior. For x
Fon cv studies of people with ran” ou getthe de woud rarely ty to ample Me M could not tl shat a
‘damage can provide very wet infor. analy such complex tc assiting pure he was looking at showed a com,
maton. inte fst place evene and tiago eplogu: but we mt the could mate Mand movements
ere not be to make fm condusors to analyze how we ela falar tata person would make on wih re

om the study of one person careful Eng word. Pos. we ue modules spect toa com. Therefore, we ancan-
ana of te pattern of deft shown at perform uncon normaly related ce with certainty tat bran domage

by an indias patient mightge sr _tohearing We a thee modulesto that prevents porn rom verbal
‘ome sa ino fr further rene "has thewerdinourheadandthen denying a parar val mage il
douce goodies or rent moter modules to convert the sounds ot nee prevent he peon am
‘oud nat be neglects. Butunder note appropriate pate often. making hand movements appropri o
some crcumstances we an daw cnc Alternative; we may picture the word that image, Perhaps the brain suo.
Sons rom single case ant to spel whch would we mode percptul tems, each with an inde
tore describa kins fin- les at perform functions elated to” pendent set of modules devoted an
ferences wecanandcannotmake Hom von [donot want go int the de. ing al image: on percept ys
cae suis let me review what we tal speling and wing here hey em connected to veal mechan
hope to accomplish by studying the be- alle covered in Copter 13, but >and he he connected to mechanisms
Pair af people with bon damage. ant out ee why important te involed wth hand movement A
Thebrainseemstobe rgaizedin ry tounderstand the functions per though we cannot ule ot ths posi

modes À gen module recover ifor- Tormes by group of moduler latent. seems unie tat he organs
Imation fom other modules performs para parts of the brain In practice, ton of the rain wasteful of

‘ome indsofanai,andsendsthere- means studying an alg the resources instead it seers more Ike
Au on to tr males with hi _ pattemofdefiishoum byproplewith trat no et ol module devoted
Communicates some aves the wing sin damage. to anayang vel image andthe
fof the module may change That What Kids of cochons cn me formation salted re set sr
ati comectors moy be modi make y studying angle india? callen pars ofthe rain Poss
6 Matin the tue the model Wecannotcondude that eco two hy then Mr Ms brain eon dupted
‘pond ferent to isinpus. syou behavior are mired the eis the pathy binging vial formation.
se in Chapter 2 heal ol eausedby damage toaset of common te modules med in verbal med

modesto modi her rap on. made needed tor both behavior in. am Du nt pee pa

202. ETI carrer 6: vison

ini it modes nae incon:

stances we can roper daw fm it

solo hand movements (Y thisconc- potes we ned to make further ob» mest oncsons that help sto un.
Sion were vue we mou sy that so. nations on athe patents. estan the organization ofthe bain
Catv vival pros sadcannecten Youcanseethaathough case studs and suggest hypothee test wth fr
‘Syndromes syndrome caused by à de. es do not permis to make sweeping ther nr
‘Connection between partir ses of cochons under the ight rem

‘THE STIMULUS

1. Light, form of electromagnetic radiation, can vary
in wavelength, intensity and pts it can ths give
rise to differences in perceptions of hue, brightness,

ANATOMY OF THE VISUAL SYSTEM

2. The eyes are complex sensory organs that focus an
image ofthe environment on the retina. The retina
«consists of three ayers dhe photoreceptor layer
(ors and cones), he bipolar cell layer

son cll ver
3. Information from the eye is sent tothe parsocelo
hara steral
ge eus and then to the primary visual

CODING OF VISUAL INFORMATION
INTHE RETINA

When ight strikes a molecule ofp
photoreceptor the molecule sp
Eeptor potential

Ganglion cell ofthe retina respond in an opposing
center/surrvin Bion

Colors are detected by
code is changed

otopigment ina

ANALYSIS OF VISUAL INFORMATION:
ROLE OF THE STRIATE CORTEX

7. Neurons in the rate cortex ae organized in mod:
tls, ach containing two blobs. Newrons within the
blobs respond to color; those outside the blobs re
spond won spatial frequency,
and retinal dopa

8. Visual information is processed by two

ANALYSIS OF VISUAL INFORMATION:
ROLE OF THE VISUAL ASSOCIATION CORTEX

9 Specific regions of rate cortex receive
formation about specific feature ofthe val scene
from the wre cortex, anale and send their
Formation on o higher levels of asociation cortex.

10. The astociation cortex of the inferior temporal
gras (ventral stream) recognizes the shape of ob-
jects wherea the parietal comen dorsal steam) ree
‘izes their location.

11. Damage othe visual asociaño
appereepihe or ac agi in humans.
The fasform gyrus on the base ofthe occipital lobe
isimvolved in perception of faces and other particu-
Lars complex stim. region located inthe ex-
rare cortex (U8)icimokved in color vision, The
region corresponding o area VS is involved in per

pion of movement and a nearby region (MST)
perception of optic flow

cortex can produce

(Gregory BL Be und Bin: The cig of Singh
Princeton, N} Princeton University Pres, 107

(Oper, W The human Er: Saco and Panton, Sader
Tan: MA: Sina Awe, 19

Rick, RW, The Ft Sp in Sing Sunderland, MA: Sin
er Actes BA,

in Nam 196,19 10-190
an BA. Frundatens of Vision. Sunderland MA: Saver
eA, SA Von oh ain, Oxfords Blick Scenic Pub-
Tian, 12

203. Irala anatomy pen edu-Jancoreunaetna ht

Pcp An nc oh eval Thor y Kun Kaha
a
m yorku.aiepupnchcnicsKofkaercepion!
perception him
“Thee contain a and of pons
poopie

took ar

Tatoik in Serien and Perception
Le Ponce ut Me
ho and rep Bel

Blndigh Demonstration
rend brad bin dgh hum

This roles am oie demon othe plcnome-
on kn a bing

204. Audition, the Body MTazmımma
Senses, and the
Chemical Senses

205. Allin Her Head?

Mets, jie athe sate university, lated he tot again. tino response. "Td When an innocuous sub
Iadvolnteredtobe a nbjectin an Heturned he ul gain, and tNstime, sance such asan nection of st water
sprint atthe Grtalscocl she thesimuaton made her gop and. orasuga phar anf Ike that we
ad een told ate might feat wane We recorded the voltage setting ca Ra pacto eet”
tlepombutthateveything werunder_nhisnotebook “ou mean that twas alo my
‘medial supenion andraharm woud "Okay now weknow how sets mind? That only thought that the
ame toner She Gén partly tke tot sto pin Now Fmgoing to shock hat ess
Ke des of pain buse mou be well gheyoua.drugwe ate testing Naked No Wel hati was necessary
paid and she sin ne experenean decrease the pain gute abit" Mein for youto think that you had received a
opportunity ta me up er own sel. td the dog aná air a shart whle paie But he eet wos physio:
image as bein as brave as anyone fut "Les yt tooth again. The legal one We know that becas the
‘Se entered the recapton rom, drug apparently worked: he Rati Seton injection contained a drug that
where she snd consent forms saying crue the votage considerably before counteracts th efecto opiates.”
"at sort paris nthe ex she felt any pin. “opiates? You mean Ike morphine
einen and tne ht pcan “Now sai, want ge you. orheroin™
Wald be gingers drug nd her smemereofthedugtoseitwcn Yen" Hesaw er start to proto,
Fescionto pun ould e messed. make you en evene pin” He gave shook Na Ped, andi, "No Fm sure

The experiments greeted ledherto another mean and after a te wat, you dont take dug But our brain
‘room andaikedhertobesestedinateteder again Bt the Grog had not make them For reson we sti donot

‘eval chu hein a neediest lucarne her pin any, Understand your lirio tat You had
tached to a pl be nto a enn her intended mas no reve palo cused some els
nm 30 Date ou nc gr asus he haben before to our aitor chemical tat
he aid “we want tofindout fit jection. cs te ay opiate do. he chemical
how sensitive you are to pan” He ‘After the experiment was ne the con other euros in your bai and
Showed her device thet locked some: experinente wold with Melua into cres your sami) to pan. When
thongtke anelecctothinah wih slounge“Twanttotellyousboutthe are you the second ction the
‘metal probe onthe end "Tse eperimentyouwerein,butfälke up that countras ope your

lime nerves in the pulp of your ok jou nat tak aboutitwith Sens to pin came bad”

Tooth Do you have some ings” he te people who might seve as But then, my min. y bain
node “have jou ee bite an some Subjects” She nodded he hai mate the placebo ect happen”
minar it She winced andnos. agreement wel hin about Your mind an
‘Sed agin “Good, then you wilknow "Actually, youd nat rece Your bain ar ot ely separe =
Sahat to expect” Headstedsdialon pine The fist injection mos pure Hanes can change the way you ban
simo, touted the of eat" functions and thee changes can ae
{woth and pres the button. Nove: “as? But thought made me your epics Mind and brain have
‘pone etait duels essence op” Bestie together ot senate

share a chapter. This unequal allocation of space reflects the relative impor
tance of vision tour species and the relative amount of research that has been
devoted tout. Th

chapter dde
the vestibular tem, thes

five major sections, which discuss audio
oxensesgustaton, and ofaction

For mos people

ition is the second most important sense. The value of verbal
unieation makes it even more important than vision in some respects; For ex
“Ample, blind person an join oxhersin conversation far more asl dana deat per
Son can. (Ofcourse, deaf people can se sign language o converse) Acoustic im

109

206. III cHArten >: aun in o See snd he Chr Sres rr ablorgman comieron

pan peel mero ot
ea Cs o on
loudness poeta desen
Sena comedo o er
mbr mr tam) à
cs mann oa
tympanic membrane Tie

stapes stays) The sen
ae teense

coches coke wh) Te ma.
Eos ote mr

ration about thing that are hidden from sew, and our cars work
dark. This ction describes

physiology of auditory perception.

‘The Stimulus

We hear sounds, which are produced by objects that sibrate and e
into motion. When an objet vibrate, its movements cams molecules of air sur
rounding it alternately to condense and ray (pull apar, producing waves that
travel aay from the object at approximately 700 miles per hour he vibration
‘ages beween approximately 0 and 20,000 tines per second, these waves il stir
late receptor cells in our car and wil be percehed as sound, (See Figure 7.1.)

In Chapter 6 we sie that light has shee perce bright

loue and timbre. The perceived piteh fan
frequency of bration, which is measured in hertz

(ia), or eels per second. (The ter honors Heinrich Hera ni

German physics) Loudness isa function of intensity

densations and raefactions of ai differ from each other. More vigorous vibrations

‘ofan object produce more intense sound wavesand en louer ones Timbre pro:

‘ides formation

‘of an oboe ora train whistle, Mos natural acoustic tinal are complex, consisting

fof several diferen frequencies of vibration. The particular misture determines the

sounds timbre. (See Figure 2.2.)

Anatomy of the Ear

Figure 73 shoves section through the ear and auditory anal and illustrates the ap

le and inner ext. (See Figure 73, Sound funneled va the pinta

(external ext through the ear canal 1 the Qmpanie membrane (eardrum). which
brates withthe sound.

The mide rar consis of a hollo region behind the tmpanie membrane, ap-

ne. e contains the bones of the mide car, called the oat

es soli from pat of
connects wth the panic membrane

and stapes (sierup) tothe cochlea, the truc

1x) The malleus (hammer)
vibro ia he incas (ui)
that contains the receptors The

AeA apg:

Sound waves Changes in ir peur rom sound wove move he The pyc and pect nens of ound wave,
drum and ov Ar melee ae coer together region of
ips and father spain elon allan pre. Pa!

di

aia age
press

fram mes NEN NANO
cm me AR AAA

207. Pascplte ofthe tapes press against the membrane behind the oval window, the
‘pening in the bony proces surrounding the cochlea. (See Figure 7.3)
vith fui therefore, soun

ferred ino a liquid medium. This process nor.
cent of the energy of airborne sound would be
feflected away if the ar impinged directly agains the oval window of the cochlea
‘The chain ofoncles serves san extremely efficient means of energy transmision
The bones pronide a mechanical advantage, with the baseplate ofthe tapes making
smaller but more foreful excursion against the oval window than the gmpanic
‘membrane makes aginst the malus

“The name se comes from the Greck word bh or “and sai
silshaped,conssing of wo and threequarers turns ofa grad
der

isindeed
tapering a

seal tmpanó Cirmpan 7), as shown in Figure 73. The receptive organ,

Snow ash organ of Cort, consist ofthe basilar membrane the hai, an

ral membrane. The audivory receptor cells are called hair cell, and they are a

cored, a rodike Deters cells the basilar membrane The a ofthe hai ells

Pass through the ricer monbvane, and he ends of some of them attach tothe fail

Figid teetorial membrane, which projects overhead like a shell. See Figure 7.4)

Sound waves cane the haar membrane to mone relative tothe tectoral membrane,

ich othe li of he a cli This ending produce eer pea
Georg von Bébé a cn

animal, rom human cada

Because of the physical charac
‘ends the moat determined by the frequency ofthe sun

igh frequency sounds
cease the end nearest the oval window to bed

rg of Con The nor
Iai ct Teepe cet be
Det calé Aue
rat and tpn
ne ates he oy at
Sci beset
‘et ap encre ct

208. BIE chan 7: ston Sy Sessa the Chee sense or ablongmancom/earbonte

co tn rough the cos showing the organ of art

rem SL Ee

shows this process in a cochlea that hasbeen partial straightened. If

the cochlea were a closed stem no vibration would be transmite through the mal

ind because liquids are csentillincompresible, However Ihre ia membrane:
ng the round window I enchleno,

pes ibang

transmited vo the mem-

id underneah the basar me
‘brane of the round window, which moves à manner opposite tothe
monements ofthe ex window. That, when the baseplate ofthe stapes pases i,
themembeane behind the round window bulges out. swe will se in a ater subse
tion diferent frequencies of sound vibrations can different portions ofthe haar
membrane wo Mex. (See Figur 7.5)
im people ser from a middle car disease that eases bone to grow ener the
nbrane cannot easly Mex back and forth,
aring an be revured by

changes

te one sumi veis | sona window. Beca Unir basar m
een date. | these people have a severe hearing los. However, their
3 sal procedure called fonsi window making) in which a ny hole de

eee ‘ “ill in the bone where the round window should be

209. ton
A ER TEE.

Regen 0 ou waves. When the tapes pues agaist the membrane bein the oa
‘endow the membrane etna the sound window bales outward event hgh query and

im requeny sound vernos cause ung o ren ori of the baa membrane.
‘Sra tow reguero sound raton cate ipo! he Dur membrane tx yor)

Ay

> —

Enron Bons pair ren fe bar
‘now nora lados sc a orth
[response sound parlar

Auditory Hair Cells and the Transduction
of Auditory Information

Two pes of auditory receptors, ine and outer auditory hai else on the inside
and outside ofthe cochlear col respectively. Hair cells contain ella eyelashes)

e appendages, arranged in row according to height. The human co
approximately 3300 inver hair cell, arranged in a single ro and 1
‘outer hair ell arranged in three rows The har cell form synapses with dendri
‘whose axons bring auditory information to the Bran, (Refer 10

re andthe tcctoril membras
‘rection
ice | lim Atari

anes causes the uid | Mae de mete dese
them bend back and forth too. Son are apt

dal membra
within the cochlea to How: past them, maki

210. III carrer: ston, ne 900, Sens, an me Chem sees rar alongman con/earsonte

core of actin laments surrounded by

— the insertional plaques. (See Figure 7.6.)

als opens all the ion channch, the flow of
cations into the lun increases, and he membrane de-

polarize. Asa rest, the release of ncurotransmite by the hair el increases, W
the bundle moxes in the opposite direction, toward the shortest cli, he rela

on ofthe tip ink allows the opened on channels to close. The inl of cations
eases, the membrane hyperpolarizs, and the reese of neurotranamiter de

reses (See Fire 2.7)

The Auditory Pathway
Connections with the Cochlear Nerve

The organ of Cont sends audiory information tothe brain by means of the
«cochlear nerve, a branch ofthe auditory nerve (eighth cranial ner). The neurons

that give rise tothe afferent axons that travel through this nerve are ofthe bipolar
‘ype. Their cell bodies reside in the cock nerve ganglion. (This ganglion i lso
Called the spin ganglio because it consists of lumps of cell bodies aranged in ai

‘al caused bythe curling ofthe cochlea) These neurons have axonal processes cr
Publ of weaning cion potenti, that protrude from bath ends of te oma The
End fone proces acts lite a dendrite, sponding wih exchatory postgnapti po:
‘cons wh she neurotranumitr i rlemed by the auditory hai cell: The exc
pink Ae ame | ch form mapaes wth meuronsk the medalla. (Refer to Figure 24)

aches he po one clam Each cochles I approximately 50,000 afferent axons. The den
ab sem nae drives of approximately 95 percent of these axons > hair
imertentpage er | cel Mon afferent ies ak contact wth ny one ins ha cel but cl inner
danse faste | a cell forms syapses wth approximately twenty fibers (alos, 1992) The axons
n. that receive information from the inner hir ells are thick and mycinatcd. The
ri | Saher 3 percent ofthe sensor Hers inthe cochlear nerve form amps with he
manne | much more numerous ower hair cell, at ara of approximately one Aber per

as Ay one hal cell In addin, es axons are thin and unmyelinated Th

n synapees with the fi