Central nervous system detail power point

Central nervous system

1. ArbaMinch
College of Health Science
Department of Pharmacology
Human Physiology
Neurophysiology
By Zelalem K. (MSc in Medical Physiology)
The Nervous System

2. Outlines
Introduction
Organization & function of the CNS
Sensory & motor functions of CNS
Cerebrum
Basal ganglia
Cerebellum
Brain steam
Limbic system
Neurophysiology

3. Introduction
oCentral nervous system (brain & spinal cord)
A system devoted to information processing
Protected by bony structures, membranes & fluid.
Heir, skin, skull, meninges and CSF protect brain.
oBrain is held in the cranial cavity of the skull and it consists of:
Cerebrum, cerebellum& brain stem.
oThe peripheral nerves involved are:
12 cranial nerves & 31 spinal nerves.
Neurophysiology

4. NS:a system that controls all of the activities of the body.
oIt is made up of: brain, spinal cord, nerves & senses.
The brain
The spinal cord
The nerves
The senses
Neurophysiology

5. Nervous System
CNS
PNS
Spinal Cord
Whitemater (myelin sheath)
Graymater (Cell bodies)
Brain
Myelencephalon: Medulla oblongata
Metencephalon
Pons
Cerebellum
Mesencephalon: Mid-brain
Diencephalon
Thalamus
Hypothalamus
Telencephalon
Basal ganglia
Cerebral Cortex
Frontal
Parietal
Temporal
Occipital
Dorsal root ganglia
Peripheral nerves
Cranial nerves = 12 pairs
Spinal nerves
Cervical = 8x2
Thoracic = 12x2
Lumbar =5x2
Sacral = 5x2
Coccygeal = 1x1
31 pairs
Organization of the CNS
SNS
PaNS
Autonomic NS

6. Organization of the NS…
Central nervous system[brain &SC]
Integrative & control centers
Peripheral nervous system [CN &spinal nerves]
Communicates between CNS & rest of body
Sensory division
Impulse from receptor to CNS
Motor division
Impulse from CNS to effector
ANS
To visceral organs.
SNS
To skeletal muscles.
Sympathetic Division
“Excites”
Parasympathetic Division
“Retards”
Neurophysiology

7. Spinal cord
oExtend from brain stem
oHas central grey & peripheral white
portion.
oHere, sensory and motor nerve fibers
separate into dorsaland ventralroot.
oSpinal nerves are 31 pairs:
8 … Cervical
12 … Thoracic
5 … Lumbar
5 … Sacral
1 … Coccygeal
Neurophysiology

8. Neurophysiology

9. oThespinalcordhastwo-functions:
1.Commonpassagewayforascending&descendingtracts.
oNeuronsinthewhitematteroftheSCtransmit:
i.Sensorysignalsfromperipheralregionstothebrain
ii.Motorsignalsfromthebraintoperipheralregions
2.Centerforreflexes.
oNeuronsinthegraymatteroftheSC:
Integrateincomingsensoryinformation&respondwithmotor
impulsesthatcontrolmusclesorglands.
Neurophysiology

10. Spinal cord
Gray matter
Contains nerve cell bodies.
Divided into dorsal + ventral horns.
Dorsal horn
oOrderlyarrangementofsensoryrelay
neuronsthatreceiveinputfromthe
periphery.
Ventralhorn
oContainsgroupsofmotorneurons+
interneurons.
Whitematter
oAscending+descendingtractsof
myelinatedaxons.
oAscendingpathwayscarrysensory
informationtothebrain.
oDescendingpathwayscarrymotor
commands+modulatorysignalsfromthe
braintothemuscles.
Neuroscience
Organization of the central nervous system

11. Spinal cord tracts …
Ascending tracts
oCarry information related to: touch, pain,
temperature, 2 point discrimination, position &
vibration
oGracile tract: below T6
oCuneat tract: above T7
oExample
Spinothalamic tracts: fast pain, temperature & crude
touch
Dorsal column tracts: position & vibration
Descending tracts
oCarry information associated with
motor activity like:
Posture
Balance
Muscle tone
Somatic reflex
Visceral reflex
oExample
Lateral column tracts
Ventromidial column
Ventral column tracts
Neurophysiology

12. Reticulospinaltract/Pontine
Controlofbreathing.
Emotionalmotorsystem(monoaminergicNT:5-HT,
NA,DA).
Controlthelateralhorncellsvisceral
functions/ANS;increaseautonomicsensitivity
Neurophysiology

13. Rubrospinaltract
Facilitatesflexormotorneuronsinupperlimbs
Neurophysiology

14. Lateraltectospinaltract
Responsiblefororientingtheheadandneckduringeye
movements.
Concernedwithdirectingtheeyeandturningthehead
towardsalightsource(visuospinalreflexes).
Neurophysiology

15. Ventral tectospinal tract
Concernedwithturningthehead
todirecttheearstowardsasound
source(audiospinalreflexes).
Neurophysiology

16. Medialvestibulospinaltract
oFacilitate stretch reflex and skeletal
muscle tone.
oMediate some postural reflexes.
(Corticonuclear tract)
Neurophysiology

17. Neurophysiology

18. Brain regions
1.Cerebrum
Four lobes, BG and LS
2. Diencephalon
Thalamus
Hypothalamus
Epithalamus
Mammillary body
OC
3. Brainstem
Midbrain
Pons
Medulla oblongata
4. Cerebellum
Cerebellum
Neurophysiology

19. Cerebrum
oLargestportionofthebrain(80%bymass).
oResponsibleforhighermentalfunctionsconcerning:
Perceptionoffinesensation
Learning
Memory
Speech
Judgment
Planning
oCorpuscallosum:
Majortractofaxonsthatfunctionallyinterconnectsright&left
cerebralhemispheres.
Neurophysiology

20. Commissural Fibers
Corpus callosum
Commissural fibers
Motorfunctions
Cerebralcortex
Commissuralfibers

21. Cerebral Cortex
o3 functional areas:
1.Motor: control voluntary motor
functions.
2.Sensory:allow for conscious
recognition of stimuli.
3.Association: integration.
Neurophysiology

22. Motorcortex
Sensory cortex
Auditory cortex
Visual cortex
Motorfunctions
Cerebralcortex
Cerebralcortex…

23. Cerebral cortex…
IIINeurophysiology

24. Motorfunctions
Cerebralcortex
Prefrontalcortex
Lateral orbitofrontal
Ventromedial

25. Cerebral cortex …
oEach hemisphere contains 4 lobes:
Frontal, parietal, occipital, temporal and
limbic
oHas an outer cortex of gray matter
surrounding an interiorthat is mostly white
matter.
oThe surface is marked by ridgescalled gyrus
separated by groovescalled sulcus.
Each gyruscontains one or more
functional areas called Brodmann´s areas.
Neurophysiology

26. Sensory, motor & association map
Neurophysiology

27. Functions of lobes of the brain
1.Frontal lobe =conscious thought
2.Parietal lobe =plays important roles in
integrating sensory information from
various senses
3.Occipital lobe =sense of sight; lesions
can produce visual hallucinations.
4.Temporal lobe =senses of smell and
sound.
Neurophysiology

28. Temporal lobe
1. Auditory areas
Areas-41 & 42
Receive sensory fibers from Cochlea
o1
ry
auditory center
2. Auditory association
Areas 20, 21 & 22
Interpretation of auditory information.
Neurophysiology

29. Occipital lobe
1.Visual sensory area (area-17)
Primary visual area responsible for
visionand coordination of eye
movements.
2.Visual association(area-18)
It is concerned with interpretation
of visual impulses into meaningful
written words.
Neurophysiology

30. Motor function of the cerebral cortex
oLocated in the frontal lobe, in front of
the central sulcus.
oHave 3 functional areas:
1. Primary motor area: area 4
2. Premotorarea: areas 6, 8, 44, & 45
3. Prefrontal motor association area:
areas 9, 10 & 11
Neurophysiology

31. The primary motor cortex
oLocation:
Precentral gyrus in the frontal lobe.
oBody representation:
Inverted (head-down) & crossed (opposite side) manner.
The face area is bilaterally represented.
oThe area of representationis proportional to the degree of fine
movement of the part.
e.g. large areas for heads and muscles of speech and small area for trunk
Neurophysiology

32. Neurophysiology

33. Motorfunctions
Cerebralcortex
MotorHomunculus:whythehand&faceareover-represented???

34. Function of area-4
1. Initiation of voluntary, fine, discrete movement of limbs (hands, fingers)
on opposite side.
2. Facilitation of stretch reflex
i.e. Facilitation of skeletal muscle tone & tendon jerk
Effect of lesion to area-4
1. Flaccid paralysisin the opposite side of the body.
Neurophysiology

35. The premotor cortex (area-6, 8, 44 & 45)
Area –6
oLocation:lies anterior to area 4
oBody representation:crossed &
inverted
oConnections
To area-4
Sensory areasvia sub cortical fibers
Thalamic nuclei
Neurophysiology

36. Function of area-6
1.Cooperates with area-4 in control of coordinated voluntary movement.
Isolated stimulation of area-6 initiates coordinated gross(not fine)
movementin the opposite side of the body (flexion, extension).
2.Contains the following functional areas:
Broca´s area
Frontal eye field area
Head rotation area
Hand skill area
Neurophysiology

37. oBroca´s area (areas-44 & 45)
Word formation area(speech center).
Lesionresults in aphasia(condition in which someone is unable to speak)
oFrontal eye field area (area-8)
Located above the Broca´s area connected to the visual center in the
occipital lobe.
Controls movementof eye& eyelid.
Lesion:fixation(locking) of the eye on specific objects
oHead rotation area = directs the head to objects.
oHand skill area = controls skilled movements.
Neurophysiology

38. Function of area-6 ...
3. Inhibitionof stretch reflex (suppresses muscle tone) and grasp reflex.
4. Controls complex movement like
Facial expression, jaws, tongue, larynx, pharynx & respiratory
muscles.
5. Initiates automatic (involuntary) movement performed subconsciously
(swinging movement of arms during walking).
6. Involved in the control of the ANS
Neurophysiology

39. The prefrontal motor association cortex (areas 9, 10, 11)
Location
Anterior part of the frontal lobe
It is called the organ of mind
Prefrontal cortex
Connections with
HT
Thalamus
Limbic system
Motor areas
Temporal
Occipital lobes
Neurophysiology

40. Function of area 9,10,11
1.Involvedinhigherintellectualfunctionsofthebrain;
Planning,intelligence&elaborationofthought.
2.Duetoitsconnectionwithhippocampus,itisinvolvedinthestorage
ofrecentmemory.
3.Duetoitsconnectionwithhypothalamus,itisinvolvedinthecontrol
oftheANS.
4.Duetoitsconnectionwiththelimbicsystem,itisinvolvedincontrol
ofemotionalbehaviors.
Neurophysiology

41. Frontal/Temporal/Amygdaloid Lobotomy
•Kluver-Bucy Syndrome
Altered emotions (placid):
Reduced fear & aggressiveness
Difficulty of planning and
working towards goals
Oral tendencies to identify
object
Hypemetamorphosis:
irresistible urge to run around
objects touch and taste them
Psychic blindness to choose
food
Altered sexual behavior:
masturbations, heterosexual
and homosexual (low moral
standard)
Phineas Gage…1848

42. Cortical areas controlling autonomic function
1.Limbic system
2.Premotor area (area 6): micturition,
salivation
3.Frontal eye field area (area 8):
lacrimation, pupillary changes
4.Prefrontal areas: through their
connections with hypothalamus
control autonomic functions.
Neurophysiology

43. oSensory function of the cerebral cortex
Thehighest center fortheperception offine sensations.
Somatic sensations (touch, pain, T
o
, pressure, 2 point discrimination,
position, vibration, proprioception and …) perceived in the parietal lobe
Visual sensation in the occipital lobe.
Auditory sensations in the temporal lobe.
Gustatory sensation in cingulate cortex
Olfaction in olfactory bulb
Neurophysiology

44. Somatosensory areas
oTwosomatosensoryareasare:
1.The primary somatosensory
areas (S
I)
2.The secondary somatosensory
areas (S
II)
Neurophysiology

45. Primary somatosensory areas (S
I)
Location:
Postcentralgyrusofthe
parietallobe.
IdentifiedbyBrodmann´s
areas3,1&2
Finalterminationoffine
somatosensorypathways
projectedfromthalamic
nuclei.
1
23
Neurophysiology

46. Body representation:
Crossed & inverted
Each half of the body represented in the
contra lateral cortex.
Upper half of the face is bilaterally
represented.
Area of representation in each part is
proportional to the number of receptors
in the partnot with its size.
Neurophysiology

47. Sensoryhomunculus:verysensitivearearepresentedinmorearea
Neurophysiology

48. Functionof S
I
oPerception of the following sensations:
1. Fine touch, tactile localization & discrimination.
2. Localization of pain & temperature.
3. Texture of materials differentiation.
4. Properioception.
5. Transmits sensory information to areaS
II &
somatosensory association areafor farther elaboration of sensory
information.
Neurophysiology

49. Secondary somatosensory areas (S
II)
Location: behind S
I.
Represented by Brodmann´sarea-40
S
IIreceives signal inputs from S
I, thalamic nuclei, visual andauditory
sensory areas.
Function:
Potentiates the function of S
I, but not essential for these functions.
S
Ican work without S
II, but the other way round is not true.
Neurophysiology

50. Somatosensory association area
oLocation:(areas 5 & 7)
oConnections:receive sensory impulse from S
I , S
II , thalamus, visual
cortex &auditory cortex.
oFunctions:
1. Combines all sensory signals to give meanings to the sensory input.
2. It is important for stereognosis.
Effect of lesion to this areas ; astereognosis; failure to identify objects by
their touch, shape, weight & texture.
Neurophysiology

51. Sensory areas
oFound in the parietal,
occipital & temporal lobes.
1.Somatosensory cortex.
2.Somatosensory association
cortex.
3.Visual areas.
4.Auditory areas.
5.Olfactory cortex.
6.Gustatory cortex.
7.Vestibular cortex
Neurophysiology

52. Language areas
oWernicke’s area
Understanding oral
& written words.
oBroca’sarea
Speech production.
Neurophysiology

53. Language areas …
oBroca’s area (area 44,45)
Involves articulation of speech.
In damage, (aphasia) but comprehension of
speech is unimpaired.
oWernicke’s area (area 39,40)
Involves language comprehension.
In damage, language comprehension is destroyed
andspeech is rapid without any meaning.
Neurophysiology

54. Language areas …
oAngular gyrus:
Center of integration of auditory, visual
information.
Damage produces aphasias.
oArcuate fasciculus (neural pathway)
oTo speak intelligibly, words originating in
Wernicke’s areamust be sent to Broca’s area.
oBroca’s area sends fibers to the motor cortex which
directly controls the musculature of speech.
Neurophysiology

55. Arcuate fasciculus
Motorfunctions
Cerebralcortex

56. Lateralization
oThe fact that certain activities
are almost exclusively dominant
on 1 of the 2 hemispheres.
In most people, theleft hemispherehas a more control overlanguage,
math, &logic.
While the right hemisphereis geared towards musical, artistic &
othercreative endeavors.
oMost individuals with left cerebral dominance are right-handed.
Neurophysiology
LA
TE
RA
LI
ZA
TI
ON

57. Thalamus
o80% of the diencephalon.
oForms most of the walls of the 3
rd
ventricle.
oOvoid mass of gray matter/egg-shaped
structure
oPaired structures, located on both sides of the
third ventricle.
oConnected by interthalamic adhesion
oEach thalamus has 4 groups of nuclei (>50
nuclei).
Neurophysiology

58. Significance
Relaystation/‘gatekeeper’,‘secretaryofthecerebralcortex’
MediatesALLtypesofsensationstothecerebralcortex…
(exceptolfaction).
Connectscorticalareaswitheachother(integrating,modulating+gating,
bidirectionalflowofinformation,finetuning…).
Motorintegration(inputsfromcortex,cerebellum+basalganglia).
Painmodulation(allnociceptiveinformation…).
Arousal(partofRAS).
Neuroscience

59. Thalamus as relay…
Linkbetweensensoryreceptorsand
cerebralcortexforallmodalitiesexcept
olfaction.
Neuroscience

60. Thalamic nuclei
MGN
LGN
/LP
/DM
/ANT
/VA
/LD
/VL
VPL
VPM
Neuroscience

61. oThehypothalamus
Formsthefloor+lateralwallof
thirdventricle
Inferiortothalamus.
Componentofthelimbicsystem.
Weighs4gm.
Connectedtothepituitaryglandby
thepituitarystalk.
Neuroscience

62. Function of hypothalamus
1. ControlstheANS
Anterior nuclei acts as a parasympathetic center.
Posterior nuclei acts as a sympathetic center.
2.Endocrine function
oControls:
Adenohypophyseal hormones.
Neurohypophyseal hormones.
Neuroscience

63. 3.Regulationofbodytemperature
Heatlosingcenter(anteriorHT)
Heatgainingcenter(posteriorHT)
Thermostatcenter(anteriorpreopticarea)
4.Regulationofsleep,wakefulness,emotions,sexualarousal,anger,
fear,pain&pleasure.
5.Controlsfoodintake(hungersensation):
Feedingcenter(lateralHT)
Satietycenter(ventromedialHT)
Neuroscience

64. 6. Control of water-electrolyte balance
Thirst center (lateral HT)
Osmoreceptors(anterior HT)
7. Control of sexual behavior: libido, sexual activities are controlled by
cerebral cortex, limbic system & HT.
8. Regulates sleep: lesion to posterior HT-Somnolence.
Neuroscience

65. 9. Regulates MR
By stimulating calorigenic hormones such as
oT
3/T
4, AD, NA, glucocorticoids.
10. Controls milk letdown and utrine contraction.
oEffect of HT lesion:
Diabetes inspidus
Hypo/hyperthermia
Sleep, emotional & hormonal disturbance
Hyperphagia
Neuroscience

66. Thehypothalamicnuclei
Hypothalamicnucleiareclassifiedintofivegroups:
1.Anteriorgroup
Preoptic
Supraoptic Regulateshormonereleasefromposteriorpituitary
Paraventricular
Suprachiasmatic
Anterior
2.Middlegroup
Arcuatenuclei
Ventromedial
Dorsomedialnuclei
(Regulates ANS)
Neuroscience

67. 3.Posteriorgroup
Posteriorn
Premammillaryn.
Medial
Lateraln
4.Lateralzone
Lateralhypothalamicnucleu(limbicsystemstructures,emotion
control)
5.Periventricularnucleus
Graymatteradjacenttothirdventricle.
(Releaseofendocrinehormonesfromanteriorpituitarygland).
Neuroscience

68. Are deep nuclei of the cerebrum
(masses of graymatter).
Aid the motor cortex in planning +
generating motor actions.
Kick starter of the voluntary
movement
Neuroscience
BasalGanglia

69. Motorfunctions
Basalganglia
Basal ganglia and the major components of the motor system…

70. Motorfunctions
Basalganglia
Anatomical relations of the basal ganglia to the cerebral cortex + thalamus

71. Motorfunctions
Basalganglia
•Cortico–BasalGanglia–
ThalamocorticalMotor
Circuit
VI
Connections between the cerebral cortex, thalamus, basal
ganglia, cerebellum, brainstem, & spinal cord.

72. Rolesofthebasalgangliainthemotorcontrol
Neuroscience

73. oBG:4principalstructures:
i.Striatum(caudate+
putamen)
ii.Globuspallidus(GPe+GPi).
iii.Substantianigra
iv.Subthalamicnucleus.
Basalganglia
Neuroscience

74. oThreelargenuclearmasses
Caudatenucleus
Striatum/neostriatum/corpusstriatum
Putamen
Lentiformnucleus
Globuspallidus/GPi+Gpe
(paleostriatum)
oTwofunctionallyrelatednuclei:
Subthalamicnucleus(STN).
Substantianigra(SN)
•Pars compacta(SNc)
•Pars reticulata(SNr)
Neuroscience

75. Caudatenucleus
oAtadpole-shapednucleus
oItsheadliesinthefloorofthelateral
ventricle.
oItsbodyarchesoverthethalamusasaC
shape.
oTaillyingintheroofoftheinferiorhornof
thelateralventricle.
oControlofeyemovement+cognitive+
affectivebehavior.
oGABAergicneurons
Neuroscience

76. Putamen
oMostlateraloftheBG.
oAnteriorlimboftheinternalcapsule
separatescaudateandputamen.
oPutamen+caudatenuclei:inputnuclei
totheBG.
oReceivemainlyexcitatoryinputfrom
cortical+subcorticalstructures
oGABAergicneurons
Neuroscience

77. Globuspallidus/GP
oGP:medialtotheputamen+lateraltothe
thalamus.
oGPe+GPi
oGPistheoutputnucleus(inhibitory
projectionstothethalamus,GABAergic).
oGPi:majoroutputstructuresoftheBG
Neuroscience

78. Subthalamicnucleus/STN
oAbiconvexnucleus,liesinferiortothethalamus+superiortotegmentumofthe
midbrain,caudaltothehypothalamus
oReceivesafferentsfromboththecortex+GPe.
oOutputisexcitatorythruglutamatergicprojectionstotheGPi+SN
o‘Clock’ofbasalganglia/definestheoutputrhythm.
Nucleusaccumbens
•Theanterior+ventralpartofthestriatumwheretheheadofthecaudateand
putamenarecontinuouswitheachother.
•Receivesextensivedopaminergicinput+anintegralpartofthelimbicsystemand
rewardcircuitry.
Neuroscience

79. Substantianigra
oLocatedintherostralmidbrainwithin
thecerebralpeduncleatthelevelof
thesuperiorcolliculi.
oContainsdopaminergicneuronsthat
projecttotheputamen+caudate+
STN.
oSNc(dopaminergiccells)
oSNr(GABAergic).
Neuroscience

80. CategoriesofBGnuclei
oInputnuclei/zones
CaudatenucleiAch,GABA
PutamenAch,GABA
oIntrinsicnuclei
Globuspallidus(Gpe)GABASTN
Subthalamicnucleus(STN)GlutamateGpi,SNc
Substantianigra(SNc)DAStriatum
oOutputnuclei
Globuspallidus(Gpi)GABAVA,VL&DM
Substanianigra(SNr)GABASTN,VA,VL&DM
Neuroscience

81. oFiberstoandfromBG
Corticostriatalfibersfibersfromthecortextothestriatum
NigrostriatalpathwaytheconnectionbetweentheSNandthe
striatum
SubthalamicfasciculustheconnectionbetweentheSTNandthe
Gpi
ThalamicfasciculusistheprojectionfromtheGpitothethalamus
StriatopalidalfibersfibersfromthestriatumtotheGp
Neuroscience

82. Neurotransmitters in the basal ganglia…
FibersfromthecerebralcortexGlucorpusstriatum.
FibersfromthesubstantianigraDAcorpusstriatum.
FibersfromthecorpusstriatumGABAGP.
FibersfromthecorpusstriatumGABASNr.
FibersfromthebrainstemNA+serotonin+enkephalinBG
NB
ExcitatoryNT:Glu + Ach + NA + DA (D
1).
InhibitoryNT: DA (D
2), GABA, serotonin + enkephalin.
Neuroscience

83. Motorfunctions
Basalganglia
Red:Excitatorypathways
Gray:Inhibitorypathways
Inputs:striatum(putamen+caudate)+STN
Outputs:GPi+SNr
oThalamicnuclei(VL,VA,CM)
Thebasalganglia–thalamocorticalcircuitry.

84. Neuronalconnectionsofthebasalganglia
oInternalcircuits
•Inputiswellintegrated+theoutputhighlyregulated.
•Balanceofinhibitory+excitatorypathwaysthalamuscortex.
•Thalamusisundertonicinhibition(unlessinhibitionisremoved,thereisno
signalingtothecortex).
•StriatumGP+SNr.
•Outputcaneitherdecreaseorincreasethetonicinhibitionofthethalamusvia
twointernalpathways(direct+indirectpathways).
Motorfunctions
Basalganglia

85. 1.Directpathway
oExcitatoryprojectionsfromthecortexStriatum
oInhibitoryneuronsfromstriatumGPi.
oGPiinhibitoryneuronsthalamus.
oInhibitionoftheinhibitionreleasesthetonicinhibitionofthethalamus
oThethalamusthensendsexcitatoryfiberstothecortex.
oMorecorticaloutputresultsfromincreasedexcitationofthecortex.
oAtthesametime,thestriatumisalsoinfluencedbyinputfromtheSN.
oDAneuronsprojecttothestriatumwheretheyexcite(viaD
1receptors)inhibitory
neurons,whichprojecttotheGPi.
oTheSNenhancestheexcitatoryinputfromthecortex.
Neuroscience

86. The direct pathway
Neuroscience
DA
Glu
Glu
GABA
GABA
GABA
Glu

87. 1.Direct pathway…
oFacilitates target-oriented + efficient behavior.
oDisinhibits thalamus from tonic inhibition thalamocortical
activity.
oMore excitation of the cortex and in turn more cortical output,
facilitates movement (positive feedback).
Neuroscience

88. 2.Indirectpathway
oThiscircuitinhibitstheoutputfromthethalamus
oLeadingtolessexcitationofthemotorcortexandlessmotoroutput
oPuts“brakes”onthedirectpathway
oInhibitsthethalamocorticalactivity(excitationofthemotorcortex+
lessmotoroutput(negativefeedback).
oInhibitsmovement.
Neuroscience

89. Theindirectpathway
Neuroscience

90. Connections of BG
1.Cerebral cortex via
I.Caudate circuit
II.Putamen circuit
2.Brainstem via
I.Extrapyramidal tracts
Vestibular nuclei
Reticular formation
Tectum
Red nucleus
Olivary nucleus
Neuroscience

91. Connection of BG to cerebrum
Caudate circuit
oFrom association area +M1 + M2+
sensory association area
Caudate nucleus
Globus pallidus
VLNT
Motor association area
Neuroscience

92. Role of caudate circuit
oConvert motor thoughts, ideas and plans to motor action
What pattern of movement will be used
oDetermines the time and scale movement
To what extent the movement will be fast
For how long the movement will last
oDamage to caudate circuit
Disorganized motor activity; wearing neck tie before a shirt
Failure to scale a contra lateral side (when drawing)
Neuroscience

93. Putamen circuit
Motor Association +M1+ M2
Putamen
Globus pallidus
VLNT
M1 + M2
Accessory circuit that involve STN
and SN
Neuroscience

94. Role of putamen circuit
oStorage of motor circuit of familiar actions
Signature, writing, lighting candle
oDamage to this circuit
Motor apraxia;inability to carry out familial movements in the absence
of motor paralysis
Inabilityto writeor draw figures with a fixed scale
oExcluding the contralateral side of the body from any motor plans.
Neuroscience

95. Cerebellum
oLies inferior to the cerebrum &
occupies the posterior cranial
fossa.
o2
nd
largest regionof the brain
10%of the brain by volume,
but contains 50%of neurons.
Neuroscience

96. The cerebellum controls your
Balance Posture
Motor Skill
Neuroscience

97. Cerebellum...
Neuroscience

98. Cerebellum: functional parts
oVestibulocerebellum[archicerebellum]
It is the oldestpart of the cerebellum.
It consists of flocculonodularlobe.
It is mainly connected to the vestibular apparatus.
Function: controls equilibrium& posture
oSpinocerebellum[paleocerebellum]
It comprises vemis& paravermalparts.
It receives signal from muscle spindle & golgitendon organs.
Function: concerned mainly with control of muscle tone.
Neuroscience

99. oCerebrocerebellum(neocerebellum]
It includes the lateral cerebellarhemispheres.
It is the newestpart
Connected to cerebrum.
Function: control of skilled voluntary movements initiated by
cerebral cortex.
Ex playing piano, writing, driving…
Neuroscience

100. Cerebellar connections
oTractsthat link the cerebellumwith the brain
stem, cerebrum, & spinal cord leave the
cerebellar hemispheres as the superior, middle, &
inferior cerebellar peduncles.
1.SCPcarries instructions from cerebellar
nuclei to the cerebral cortex.
2.MCPconnects pontin nuclei to the
cerebellum.
3.ICPconnects the cerebellum& the medulla
oblongata
Neuroscience

101. Cerebellar connections …
Neuroscience

102. Functions of cerebellum
1.Controlofposture&equilibrium.
2.Controlofmuscletone
3. Control of voluntary movement
a. Planning
Cerebrocerebellumis concerned with the intention& planof movement.
b. Timing of movement
Cerebellum determines the start& terminationof sequential movement.
c. Damping of movement
Ending of movement without oscillation.
d. Ballistic movement
Rapid & short movement such as typing.
Neuroscience

103. The Brain Stem [Mid brain; Pons; Medulla]
•Extended between the spinal
cord & sub cortical structures
(thalamus, HT, BG).
•Connected with cerebellum by
cerebellar peduncles.
•Contents:
–Ascending & descending
tracts
–Vital controlling centres
–Reticular formation
–Nuclei of cranial nerves
Neuroscience

104. Midbrain
oContains both sensory& motor tracts &
important nuclei
1. Superior colliculi: involved invisual reflexes.
The reflex center for the movement of eyes
& head in response to visual stimuli.
2. Inferior colliculi: relay centers for auditory
information.
oThe reflex center for the movement of head
& neck in response to auditory stimuli.
3. Red nucleus: works with BG& cerebellumto
coordinatemuscle movement
Neuroscience

105. Pons
oContains: tracts & several nuclei
of CN V, VI, VII.
oPontin nucleus: which is a relay
stationfor impulses discharged
from the cerebral cortex to the
cerebellum via cortico-ponto-
cerebellar tract.
oApneustic & pneumotaxic
respiratory centers.
Neuroscience

106. Medulla oblongataoContains ascending & descending tracts &
vital controlling centres:
Cardiovascular , respiratory,
swallowing, vomiting center and
salivatory nuclei.
oIs the origin of cranial nerves (CN VIII to XII)
oOther nuclei with specific functions are:
oOlivatory nuclei: regulation of muscle
tone
oVestibular nuclei: regulation of muscle
tone, posture & equilibrium.
Neuroscience
Midial lemniscus

107. The Limbic system
Forebrainnuclei & fiber tracts that
form a ring around thebrain stem.
Center for basic emotional drives.
Consists of structures that make
the border between neocortex&
BS.
Has 2 components
Neuroscience

108. Components of the Limbic system
1.The limbic lobe: (lower, older
part of the cerebral cortex):
Subcallosal gyrus
Cingulate gyrus
Hippocampus
Fornix
Entorhinal cortex
Olfactory bulb.
2.A group of deep structures:
intimately associated with the limbic
lobe:
Hypothalamus
Amygdala
Anterior nucleus of the thalamus
Septal nuclei in the upper midbrain
also called septal midbrain area
(SMA).
Neuroscience

109. Neuroscience
Thelimbicsystem

110. Function of the limbic system
1.Olfaction
Oldest function of the limbic system.
It is concerned with perception, discrimination & coordination of olfactory
sensation.
2.Emotion
Amygdala& HTcontrol the somatic, autonomic, endocrine & behavioral responses
in state of emotion.
Stimulation of amygdaloid nuclei produces anger, fearor rage.
Destruction of amygdaloid nuclei abolishesfearand aggression.
Neuroscience

111. 3.Memory
Itplaysanimportantroleinsortingouttheinformation&deciding
whichinfotobestoredinmemoryaswellasforencoding&
consolidationofmemory.
Particularly,hippocampus&amygdalaplaycrucialroleinmemory&
learning.
4.Motivation:
Itcontainsthereward&punishmentcenterswhichareresponsiblefor
motivationtotakeoravoidcertainactions.
Neuroscience

112. 5. Control of feeding behavior
LS, particularly the amygdala is concerned with sorting out the type of food into
edible& inedibletype.
Lesion to amygdaloid nuclei results in hyperphagia.
The subject with amygdaloid lesion tries to eat any available unlike lesion to the
hypothalamic satiety center.
6. Control of the ANS
Neuroscience

113. 7. Control of sexual behavior:
Sexual behavior in human is largely controlled by the cerebral cortex.
But the instinctual desire & reaction are the function of LS & HT.
Lesion to piriformcortex in the periamygdaloidarea produces
hypersexuality.
8. Control of the maternal behavior
Neuroscience

114. Memory
oThe ability of the brain to storeinformation & recallit at a later time.
oStorage capacity of human brain 3x10
8
bit
The unit of information is `bit`
The simplest form of sensory experience
e.g. A figure, a sound, smell.
Neuroscience

115. Memory…
oInfo flow to the brain.
During quite reading, the rate of info flow to the brain is 40 bits/sec
During mental calculation, it is 12 bits/ sec
During countingit is 3 bits/sec
oAn averagerate of info flow is 20 bits/sec .
Neuroscience

116. Types of memory
oThere are 4 types of memories
1.Sensory memory (immediate memory)
2.Primary memory (short-term memory)
3.Secondary memory (long-term memory)
4.Tertiary memory (permanent memory)
Neuroscience

117. 1.Sensory memory[immediate memory]
oStorage of sensory info for few seconds.
oForgetting starts immediately after the info is acquired.
oInfo in sensory memory can be transferred into primary or secondary
memory.
Neuroscience

118. 2.Primary memory[short-term memory]
Memory that lasts from a few minutes to few Hrs.
Info enters this memory by verbalization.
Primary memory is not stored in infants &animals.
The capacityof primary memory is small,but rate of retrieval is rapid.
Neuroscience

119. 3.Secondary memory[long-term memory]
Memory that lasts for hours, days or years.
Info is introduced into this memory by two means:
1.From the sensory memory, through stimulation of reward or
punishment system.
2.From the sensory and primary memories by practiceor rehearsal.
Neuroscience

120. 4.Tertiary memory[permanent memory]
The info stored never forgotten.
e.g. One´s name, ability to read & write.
Info in the tertiary memory comes from secondary memory by years of
practice, which consolidatesmemory.
Can not be erased by brain injury and diseases.
Access to retrievetertiary memory is rapid.
Neuroscience

121. Consolidation of memory
oThetransfer of info from the primary short -term memory intothe
secondary long -term memory.
oThis process takes from 5 min -2 hrs.
Neuroscience

122. Memory encoding
oClassification&placingofmemoryitemsintheirpropermemorystores
inthebrainaspartofconsolidationprocess.
oHippocampusplaysacentralroleinmemoryencoding.
Neuroscience

123. Characteristics of different typesof memories
CharactersSensory Primary Secondary Tertiary
Capacity: Very small Small Very large Large
Duration: Few secondsSeveral min-hrsSeveral hrs-yrsPermanent
Entry intoAutomatic duringVerbalizationPractice, rewardFrequent
Storge: perception punishment practice
Rate of retrieval:Very rapid Rapid Slow Very rapid
Type of Info:Sensory Verbal All forms All forms
Mechanis ofSynaptic Long-term Structural and functional
Storage: potentiation potentiation modification of memory traces
Mehanism ofFading & New info Proactive or retro-No forgett-
Forgetting extinction replaces the oldactive inhibition ing
Neuroscience