cerebral cortex 1

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1.Forebrain1.Forebrain : Telencephalon: Telencephalon1

NEUROLOGY

Dr.G.Bhanu Prakash


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Forebrain (prosencephalon) =Forebrain (prosencephalon) =??? + ?????? + ???

TelencephalonTelencephalon Largest Brain divisionLargest Brain division

Major Components:Major Components:

??? structures??? structures of the Telencephalonof the Telencephalon

e.g. Basal Forebrain, Amygdala, Basal Ganglia, Striatume.g. Basal Forebrain, Amygdala, Basal Ganglia, Striatum

?????? trackstracks

e.g.e.g. corona radiata, internal capsulecorona radiata, internal capsule

????????

e.g.e.g. primary motor cortex, Brocas areaprimary motor cortex, Brocas area2

Forebrain 1: TelencephalonForebrain 1: Telencephalon


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Forebrain (prosencephalon) =Forebrain (prosencephalon) =telencephalon + diencephalontelencephalon + diencephalonTelencephalonTelencephalon

Largest Brain divisionLargest Brain division Major Components:Major Components:

Subcortical structuresSubcortical structures of the Telencephalonof the Telencephalon

e.g. Basal Forebrain, Amygdala, Basal Ganglia, Striatume.g. Basal Forebrain, Amygdala, Basal Ganglia, Striatum

White matterWhite matter trackstracks e.g. corona radiata, internal capsulee.g. corona radiata, internal capsule

Cerebral CortexCerebral Cortex

e.g. primary motor cortex, Brocas areae.g. primary motor cortex, Brocas area

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Forebrain 1: TelencephalonForebrain 1: Telencephalon


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OverviewOverview

Cortical organization (lamina)Cortical organization (lamina)

Cell types/ Layers/ ConnectionsCell types/ Layers/ Connections

vertical organizationvertical organization Types of cortexTypes of cortex

Brodmanns AreasBrodmanns Areas

Cytoarchitecture and relation to functionCytoarchitecture and relation to function

Key Brodmanns AreasKey Brodmanns Areas

Major White Matter tracts of the Cerebral cortexMajor White Matter tracts of the Cerebral cortex

Internal CapsuleInternal Capsule

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Descriptive AnatomyDescriptive Anatomy

to function (overview)to function (overview) Histological staining (Cell Bodies)Histological staining (Cell Bodies)

DiscoveredDiscovered ?????? arrangement of the cortexarrangement of the cortex

?????? are defined byare defined by cell type, size andcell type, size anddensitydensity

Broadmans areasBroadmans areas Regions of the cortex haveRegions of the cortex have unique ???unique ???

GaveGave numbersnumbers to each of theseto each of these ??????(Broadmans areas)(Broadmans areas)

Broadmans areas and cortical functionBroadmans areas and cortical function Laminar layers haveLaminar layers have ?????? correlatescorrelates

Size of these layers are related to theSize of these layers are related to the ??????

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Descriptive AnatomyDescriptive Anatomy

to function (overview)to function (overview) Histological staining (Cell Bodies)Histological staining (Cell Bodies)

DiscoveredDiscovered laminarlaminar arrangement of thearrangement of thecortexcortex

LaminaLamina are defined by cell type, size andare defined by cell type, size and

densitydensity Broadmans areasBroadmans areas

Regions of the cortex haveRegions of the cortex have unique laminarunique laminarpatternspatterns

GaveGave numbersnumbers to each of theseto each of these laminarlaminar

patternspatterns (Broadmans areas)(Broadmans areas) Broadmans areas and cortical functionBroadmans areas and cortical function

Laminar layers haveLaminar layers have functionalfunctional correlatescorrelates

Size of these layers are related to theSize of these layers are related to theareas functionareas function

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Cerebral CortexCerebral Cortex the Basic Insthe Basic Ins

andO

utsandO

uts Afferent fibers enterAfferent fibers enter ??????

?????? process the afferentprocess the afferent

informationinformation

?????? fibers convey thefibers convey theprocessed information toprocessed information toanother siteanother site

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Cerebral CortexCerebral Cortex the Basic Insthe Basic Ins

andO

utsandO

uts Afferent fibers enterAfferent fibers enter

cortexcortex

Local circuitsLocal circuits process theprocess theafferent informationafferent information

EfferentEfferent fibers convey thefibers convey theprocessed information toprocessed information to

another siteanother site

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Interneurons???

output

Cell Types and laminar locationsCell Types and laminar locations: Local: LocalCircuit (interneurons)Circuit (interneurons) Local circuit neuronsLocal circuit neurons AKAAKA

interneurons, intrinsic neuronsinterneurons, intrinsic neurons

?????? do not leave the immediate region ofdo not leave the immediate region ofcell body, can cross into different laminarcell body, can cross into different laminarlayerslayers

Inhibitory, containInhibitory, contain ??? (1 exception)??? (1 exception)

FunctionFunction ?????? FormulateFormulate rhythms, coordinate outputsrhythms, coordinate outputs

InterneuronsInterneurons classified byclassified by ??????

?????? -- Laver IVLaver IV

?????? (have spines)(have spines) Receptive field IIReceptive field II IVIV

Excitatory (Glutamate)Excitatory (Glutamate) ??????(lack spines)(lack spines)

Receptive field mainly IVReceptive field mainly IV

?????? Layers III And VLayers III And V

Receptive field (all layers)Receptive field (all layers)

?????? Layer IIILayer III

Receptive field mostly layer IIIReceptive field mostly layer III

Aspiny Spiny

??????


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InterneuronsStellate

(granule) cells

output

Cell Types and laminar locationsCell Types and laminar locations: Local: LocalCircuit (interneurons)Circuit (interneurons) Local circuit neuronsLocal circuit neurons AKAAKA

interneurons, intrinsic neuronsinterneurons, intrinsic neurons AxonsAxons do not leave the immediate regiondo not leave the immediate region

of cell body, can cross into differentof cell body, can cross into differentlaminar layerslaminar layers

Inhibitory, containInhibitory, contain GABA (1 exception)GABA (1 exception)

FunctionFunction regulate inputs to and fromregulate inputs to and from

pyramidal cells (cortical output cells)pyramidal cells (cortical output cells) FormulateFormulate rhythms, coordinate outputsrhythms, coordinate outputs

InterneuronsInterneurons classified byclassified by morphologymorphology Stellate (granule)Stellate (granule) -- Laver IVLaver IV

SpinySpiny (have spines)(have spines) Receptive field IIReceptive field II IVIV

Excitatory (Glutamate)Excitatory (Glutamate)

AspinyAspiny (lack spines)(lack spines) Receptive field mainly IVReceptive field mainly IV

BasketBasket Layers III And VLayers III And V Receptive field (all layers)Receptive field (all layers)

ChandelierChandelier Layer IIILayer III Receptive field mostly layer IIIReceptive field mostly layer III

Aspiny Spiny

Basket

cellsChandelier

cells


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inputs

output

Pyramidal cells: most

???

???

???

inputs

output

inputs

output

Cell Types and laminar locations:Cell Types and laminar locations: PyramidalPyramidal

(output neurons)(output neurons)

Cortico-

cortical

terminas

Pyramidal cells size by lociPyramidal cells size by loci Layer VILayer VI ??????; layer II&III; layer II&III ??????; layer V; layer V ??????

Layer VI pyramidal cellsLayer VI pyramidal cells

InputsInputs --DendritesDendrites span layersspan layers ??????

O

utputsO

utputs ?????? Layer II & III pyramidal cellsLayer II & III pyramidal cells

InputsInputs DendritesDendrites span layersspan layers ??????

OutputsOutputs ??????

Layer V pyramidal cellsLayer V pyramidal cells

?????? (largest pyramidal neurons)(largest pyramidal neurons) primary ???primary ???(upper motor neurons)(upper motor neurons)

InputsInputs ??????

OutputsOutputs ??????,, ???, ???, ??????, ???, ???


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inputs

output

Pyramidal cells: most

small

Medium

large

inputs

output

inputs

output

Cell Types and laminar locations:Cell Types and laminar locations: PyramidalPyramidal

(output neurons)(output neurons)

Cortico-

cortical

terminas

Pyramidal cells size by lociPyramidal cells size by loci Layer VILayer VI smallsmall; layer II&III; layer II&III small tosmall to

mediummedium; layer V; layer V LargeLarge

Layer VI pyramidal cellsLayer VI pyramidal cells

InputsInputs --DendritesDendrites span layersspan layers IVIV VIVI

OutputsOutputs Thalamus, cortex, claustrumThalamus, cortex, claustrum Layer II & III pyramidal cellsLayer II & III pyramidal cells

InputsInputs DendritesDendrites span layersspan layers II IVIV

OutputsOutputs Cortex opposite hemisphereCortex opposite hemisphere(callosal)(callosal)

Layer V pyramidal cellsLayer V pyramidal cells Betz cellsBetz cells (largest pyramidal neurons)(largest pyramidal neurons)

primary motor cortexprimary motor cortex (upper motor neurons)(upper motor neurons)

InputsInputs all cortical layersall cortical layers

OutputsOutputs Spinal cord (lower motor neurons),Spinal cord (lower motor neurons),

thalamus, striatum cortex, brain stemthalamus, striatum cortex, brain stem


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Pia

surface

WM

???? organization of cortex???? organization of cortex

Cortex is arranged inCortex is arranged in ??????

Run verticallyRun vertically(perpendicular to surface)(perpendicular to surface)

~ 1 mm in diameter,~ 1 mm in diameter,

containing 300containing 300 600 cells600 cells Neurons in a columnNeurons in a column

synapse mostly withsynapse mostly with ??????

?????? do connect near bydo connect near bycolumnscolumns

?????? is comprised of billions ofis comprised of billions of

columnscolumns Cortical columns are quasiCortical columns are quasi--

independent processingindependent processingunits that canunits that can ??????


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Pia

surface

WM

Vertical organization of cortexVertical organization of cortex

Cortex is arranged inCortex is arranged infunctional columnsfunctional columns Run vertically (perpendicularRun vertically (perpendicular

to surface)to surface) ~ 1 mm in diameter,~ 1 mm in diameter,

containing 300containing 300 600 cells600 cells Neurons in a columnNeurons in a columnsynapse mostly withsynapse mostly with otherothercells in the columncells in the column

Axon collateralsAxon collaterals dodoconnect near by columnsconnect near by columns

CortexCortex is comprised ofis comprised ofbillions of columnsbillions of columns

Cortical columns are quasiCortical columns are quasi--independent processingindependent processingunits that canunits that can act in parallelact in parallel


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Radial Glia and formation of ????Radial Glia and formation of ????

corticocortical

bundles (CC)

thalamic

radiation (TR)nucleus

basalis (NB)

monoamine

centers (MA)

Radial Glia

marginal

zone

cortical

place

subplate

zone

intermediate zone

ventricular

zone

Migration

neuron


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Radial Glia and formation ofRadial Glia and formation of

Functional ColumnsFunctional Columns

corticocortical

bundles (CC)

thalamic

radiation (TR)nucleus

basalis (NB)

monoamine

centers (MA)

Radial Glia

marginal

zone

cortical

place

subplate

zone

intermediate zone

ventricular

zone

Migration

neuron


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Each column is aEach column is a ?????? ?????? specificity for each columnspecificity for each column

i.e. a column may receive sensoryi.e. a column may receive sensoryinput from rapidly adaptinginput from rapidly adaptingmechanoreceptor receptive fieldmechanoreceptor receptive field

from the middle left fingertip (viafrom the middle left fingertip (viaspinal and thalamic pathways)spinal and thalamic pathways)

Adjacent columns may pertain toAdjacent columns may pertain to ??????from the same regionfrom the same region

i.e. a column adjacent to the onei.e. a column adjacent to the one

mentioned above may receive inputmentioned above may receive inputfrom slowly adaptingfrom slowly adaptingmechanoreceptor receptive fieldmechanoreceptor receptive fieldfromfrom the same fingertipthe same fingertip

Columns and receptive fieldsColumns and receptive fields

C

olumn contains the ???

RA = rapidly adapting receptive fieldi.e. epicritic(small filled circles)

SA = slowly adapting receptive field

i.e. protopathic

(largeopen circles)


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Each column is aEach column is a single receptivesingle receptivefieldfield single modalitysingle modality Regional functionalRegional functional specificity forspecificity for

each columneach column i.e. a column may receive sensoryi.e. a column may receive sensory

input from rapidly adaptinginput from rapidly adapting

mechanoreceptor receptive fieldmechanoreceptor receptive fieldfrom the middle left fingertip (viafrom the middle left fingertip (viaspinal and thalamic pathways)spinal and thalamic pathways)

Adjacent columnsAdjacent columns may pertain tomay pertain todifferent modalitydifferent modality fromfrom the samethe sameregionregion i.e. a column adjacent to the onei.e. a column adjacent to the one

mentioned above may receive inputmentioned above may receive inputfrom slowly adaptingfrom slowly adaptingmechanoreceptor receptive fieldmechanoreceptor receptive fieldfromfrom the same fingertipthe same fingertip

Columns and receptive fieldsColumns and receptive fields

C

olumn contains the microcircuitry for representing a single receptive field

RA = rapidly adapting receptive fieldi.e. epicritic(small filled circles)

SA = slowly adapting receptive field

i.e. protopathic

(largeopen circles)


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Haines

Laminar organization:Laminar organization: AfferentConnectionsAfferentConnections??????GlutamatergicGlutamatergic

Predominantly terminate inPredominantly terminate in layer IVlayer IV??????

??????Glutamatergic axons from corticalGlutamatergic axons from corticalregions outside of local circuitregions outside of local circuitTerminate in layersTerminate in layers II VIVI, within a, within a

single cortical columnsingle cortical column??????Origins: NonOrigins: Non--specific thalamicspecific thalamicnuclei, basal nucleus of Meynert,nuclei, basal nucleus of Meynert,Brain stem nucleiBrain stem nucleiSubstrates: glutamatergic,Substrates: glutamatergic,

cholinergic, serotonergic,cholinergic, serotonergic,noradrogergicnoradrogergicTerminates inTerminates in layers Ilayers I VIVI, across, acrossmultiple cortical columnsmultiple cortical columnsRegulates overal level of corticalRegulates overal level of corticalexcitability, arousal, sleep,excitability, arousal, sleep,

wakefulnesswakefulness


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Haines

Laminar organization:Laminar organization: AfferentConnectionsAfferentConnectionsThalamocortical afferentsThalamocortical afferentsGlutamatergicGlutamatergic

Predominantly terminate inPredominantly terminate in layer IVlayer IV((thalamothalamo--receptive layer)receptive layer)Corticocortical afferentsCorticocortical afferentsGlutamatergic axons from corticalGlutamatergic axons from corticalregions outside of local circuitregions outside of local circuitTerminate in layersTerminate in layers II VIVI, within a, within asingle cortical columnsingle cortical columnDiffuse cortical afferentsDiffuse cortical afferentsOrigins: NonOrigins: Non--specific thalamicspecific thalamicnuclei, basal nucleus of Meynert,nuclei, basal nucleus of Meynert,Brain stem nucleiBrain stem nucleiSubstrates: glutamatergic,Substrates: glutamatergic,cholinergic, serotonergic,cholinergic, serotonergic,noradrogergicnoradrogergicTerminates inTerminates in layers Ilayers I VIVI, across, acrossmultiple cortical columnsmultiple cortical columnsRegulates overal level of corticalRegulates overal level of corticalexcitability, arousal, sleep,excitability, arousal, sleep,

wakefulnesswakefulness


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Laminar EfferentOrganization:Laminar EfferentOrganization:

Corticofugal/Corticothalamic EfferentsCorticofugal/Corticothalamic Efferents

Haines

Cortico-thalamic

Corticofugal EfferentsCorticofugal Efferents

Pyramidal cells ofPyramidal cells of??????

?????? targetstargets

i.e. Corticospinal,i.e. Corticospinal,corticostriate,corticostriate,

corticobulbar, corticocorticobulbar, cortico--

tectal, corticopontine, etc.tectal, corticopontine, etc.

Corticothalamic EfferentsCorticothalamic Efferents

?????? cells mainly in layercells mainly in layer ??????

Large projections in someLarge projections in somesensory systemssensory systems


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Corticofugal/Corticothalamic EfferentsCorticofugal/Corticothalamic Efferents

Haines

Cortico-thalamic

Corticofugal EfferentsCorticofugal Efferents

Pyramidal cells ofPyramidal cells oflayer Vlayer V

NonNon--cortical (subcortical)cortical (subcortical)targetstargets

i.e. Corticospinal,i.e. Corticospinal,corticostriate,corticostriate,corticobulbar, corticocorticobulbar, cortico--tectal, corticopontine, etc.tectal, corticopontine, etc.

Corticothalamic EfferentsCorticothalamic Efferents

PyramidalsPyramidals cells mainly incells mainly inlayerlayer VI and VVI and V

Large projections in someLarge projections in somesensory systemssensory systems


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Corticocortical EfferentsCorticocortical Efferents

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Haines

Cortico-cortical:

callosal &

association

Pyramidals cells mostly located in layersPyramidals cells mostly located in layers

??????

Axons project to distal cortical targetsAxons project to distal cortical targets

notnot ?????? Terminate in layersTerminate in layers ?????? of a singleof a single

cortical columncortical column

Cortical Targets in contralateralCortical Targets in contralateralhemisphere arehemisphere are ?????? connectionsconnections

Tend to project to homologous area inTend to project to homologous area inopposite hemisphereopposite hemisphere

Cortical targets within same hemisphereCortical targets within same hemisphere(ipsilateral) are(ipsilateral) are ??????


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Corticocortical EfferentsCorticocortical Efferents

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Haines

Cortico-cortical:

callosal &

association

Pyramidals cells mostly located in layersPyramidals cells mostly located in layersII & IIII & II

Axons project to distal cortical targetsAxons project to distal cortical targets(not local projections)(not local projections)

Terminate in layersTerminate in layers II VIVI of a singleof a singlecortical columncortical column

Cortical Targets in contralateralCortical Targets in contralateralhemisphere arehemisphere are Collosal (commissural)Collosal (commissural)connectionsconnections

Tend to project to homologous area inTend to project to homologous area inopposite hemisphereopposite hemisphere

Cortical targets within same hemisphereCortical targets within same hemisphere(ipsilateral) are(ipsilateral) are Association ConnectionsAssociation Connections


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Majorcortical connection from a gyrusMajorcortical connection from a gyrus


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Majorcortical connection from a gyrusMajorcortical connection from a gyrus


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Martin

??? (95%)

??? (5%)

???

???

Up to3 layers

4-5 layers

???function

6 layers

1o sensory/motor, association area

Cognition, reasoning, perception,

speech/language

Memory (e.g., hippocampus)

Smell/Emotion (e.g., olfactory ctx)

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Cerebral Cortex Contains Regions Differing inCerebral Cortex Contains Regions Differing inPhylogenetic DevelopmentPhylogenetic Development

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Martin

Neocortex (95%)

Allocortex (5%)

Archicortex

Paleocortex

Up to3 layers

4-5 layers

Limbic function

6 layers

1o sensory/motor, association area

Cognition, reasoning, perception,

speech/language

Memory (e.g., hippocampus)

Smell/Emotion (e.g., olfactory ctx)

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Cerebral Cortex Contains Regions Differing inCerebral Cortex Contains Regions Differing inPhylogenetic DevelopmentPhylogenetic Development

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Martin

6 layers < 6 layers

AllocortexAllocortex


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Martin

???layers

cerebral cortex 1

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