Introduction To Neuroscience

1. Introduction to Neuroscience
The Search for Consciousness and
the Anatomical Basis of the Soul

2. History of Neuroscience
•Prehistory
–10,000 years ago, early hominids
–Trepanation - making a therapeutic hole in the
skull
•Ancient Egypt –
–5000 years ago; aware of symptoms of brain
damage
–Heart, not the brain believed to be the storehouse
of memories and location of the soul

3. Ancient Greece
•4th C. B.C.
–Brain is the organ of sensation
•Hippocrates (460-379 BC)
–Brain is the seat of intelligence
•Aristotle (384-322 BC)
–Heart is the center of intellect
–the brain serves to cool blood.

4. The Romans
•Galen (130-200 AD) –
–A Greek, chief physician in Rome
–As physician to gladiators, saw spinal cord &
brain injuries
–Dissected sheep to study brain
–Tried to deduce functions:
•Cerebrum is soft - recipient of sensations;
•Cerebellum is rather firm - must command the
muscles;
•Ventricles served to receive the vital humors via the
nerves, which were hollow tubes like blood vessels.
–These ideas prevailed for the next 1500 years.

5. Renaissance to the 19
th
Century
•Andreas Vesalius (1514-1564 AD)
–Outstanding anatomist and medical illustrator
–Made detailed studies of the bodies of criminals
–Paid particular attention to the ventricles
–Hydraulic view of brain function: Prevailing notion was
that fluids forced out from the ventricles could "pump
you up"
•White matter/Gray matter
–since white matter was continuous with the nerves, it
carried information to and from the gray matter
•The bumps (gyri) and grooves (sulci and fissures)
on the surface of the cerebral cortex have a
repeatable pattern from individual to individual

6. Renee Descartes
•17th C. French philosopher
•First to suggest substance dualism: material stuff & thinking
stuff
•Brain, ventricles, and nerves are tools of human behavior
shared by higher animals
•The mind is a uniquely human thing - a spiritual entity (soul)
that communicates with the brain via the pineal gland
•How do we perceive self - what creates brain consciousness?
–Descartes thought it was the pineal gland.
•Cartesian theater (Daniel Dennet)
–idea that there is a place in the brain where it all comes
together - center of consciousness or soul.
–100 billion neurons in the brain - not one center, but the
way neurons are massively interconnected (parallel
processing networks) = consciousness

7. Major Developments of the 19
th
Century
•Starting point of modern neuroscience
•Injury to the brain disrupts sensations,
movement, thought; causes death.
•Brain communicates with the body via the
nerves
•Brain has substructures which probably
perform different tasks
•Brain operates like a machine and follows
laws of nature (but the mind?)

8. Four Key 19
th
C. Observations
•Major insight #1:
• - Nerves as wires
•Major insight #2:
• - Localization of brain function
•Major insight #3:
•- The nervous system (and thus behavior) is
governed by the principles of evolution by
natural selection
•Major insight #4:
• - The neuron is the basic functional unit of the
nervous system

9. Nerves as Wires
•Benjamin Franklin - Experiments and
Observations on Electricity – 1751
•Luigi Galvani & Emil du Bois-Reymond -
1800
–Electricity to nerves can make muscles twitch
–Brain generates electricity
•Charles Bell & Francois Magendie – 1810
–Dorsal roots carry sensory information
–Ventral roots carry motor information
–Nerve trunks are mixtures of fibers going in
both directions

10. Localization of Brain Function
•Charles Bell - 1811
–proposed that motor
fibers (ventral roots)
originate in the
cerebellum and sensory
fibers (dorsal roots) in the
cerebrum
•Marie-Jean-Pierre Flourens –
–used selective removal
(ablation) to provide
experimental evidence
(largely from birds) that
Galen and Bell were right.
•Franz Joseph Gall –
–Phrenology - behavior
could be correlated with
the size of different parts
of the skull
–Foreshadowed the
localization of function to
the cerebral cortex
•Paul Broca – neurologist
–Studied patient who could
understand language, but
not speak.
–After patient’s death,
found lesion in left frontal
lobe (Broca's area)

11. Evolution of Nervous Systems
•Charles Darwin - On the Origin of Species, 1859
–Evolution by natural selection included behavior and the
nervous system
•More advanced animals have same basic nervous
system core as lower animals
–Basis of using animal models
•Nervous system is specialized for niche
–e.g. monkeys have well developed vision for their
arboreal life and rats have poorly developed vision, but
well developed vibrissae (whiskers)

12. The Neuron
•The Neuron is the basic
functional unit of the nervous
system
•Theodore Schwann –
–proposed cell theory in 1839
•The major problem was to
determine whether the
network of nerve fibers in the
brain were interconnected
like a plumbing system or
made up of distinct neurons.

13. Contemporary Neuroscience
•Molecular Neuroscience –
–biochemistry of the nervous system
•Cellular Neuroscience –
–cell biology of the nervous system
–Structure/function at the level of individual neurons
•Systems Neuroscience –
–how do neural circuits work?
–Sensory systems, motor systems, etc.
•Behavioral Neuroscience –
–how do systems of the brain interact to produce behavior?
–Source of dreams? Mind altering drugs (foods)?
•Cognitive Neuroscience –
–How does the activity of the brain create the mind?
–Descartes' Problem - self-awareness, mental imagery,
language

14. Nervous System Disorders
•The driving force behind neuroscience
•More Americans are hospitalized with neurological
and mental disorders than with any other disease
group including heart disease and cancer
•Alzheimer’s, Parkinson’s, Huntington’s :
–all caused by progressive degeneration of specific brain
areas
•Parkinson’s– cripples voluntary movements
–afflicts 500,000 Americans
•Alzheimer’s – dementia
–affects over 3 x 10
6
Americans
•Stroke – the 3rd leading cause of death in the U.S.
– annual cost $25 billion

15. Nervous System Disorders - Mood
•Mental disorders cost the U.S. $130 billion
yearly
•Depression & Schizophrenia –
–disorders of mood & thought
–15 x 10
6
Americans will experience a major
depressive illness in their lifetime
–leading cause of suicide
•Schizophrenia – delusions, hallucinations –
–affects 2 x10
6
Americans
•Alcohol and drug addiction affect virtually
every family – cost $150 billion/year

16. The Basics of Neuroscience
•The basic function of all nervous systems:
•Stimulus and response
•Example: Doorbell rings (stimulus)
–Receptors in the ear receive the stimulus
–Conductors (nerves) carry the message to the brain
– The brain interprets the message
–Conductors (nerves) carry the message from brain to
muscles
–Effectors (muscles) are stimulated and you walk to the
door!

17. Picturing Stimulus & Response

18. Structures of Stimulus & Response
•3 types of structures are required :
•Receptors
–a group of cells or an organ that detects a
stimulus and generates impulses that travel along
conductors.
•Conductors
–nerve cells that carry the message to and from the
brain and/or spinal cord
•Effectors
–structures that react to the original stimulus;
muscles or glands