Cerebral Cortex 1

Forebrain 1: Telencephalo n Bill Truitt Office: MS 513 278.9050 [email protected]

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Forebrain 1: Telencephalon  Forebrain (prosencephalon) =

??? + ???  Telencephalon  Largest Brain division  Major Components:

 ??? structures of the Telencephalon  e.g. Basal Forebrain, Amygdala, Basal Ganglia,

Striatum

 ??? tracks  e.g. corona radiata, internal capsule

 ????  e.g. primary motor cortex, Broca’s area…

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Forebrain 1: Telencephalon  Forebrain (prosencephalon) =

telencephalon + diencephalon Telencephalon  Largest Brain division  Major Components:  Subcortical structures of the

Telencephalon

 e.g. Basal Forebrain, Amygdala, Basal Ganglia,

Striatum

 White matter tracks  e.g. corona radiata, internal capsule

 Cerebral Cortex

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Overview  Cortical organization (lamina)  Cell types/ Layers/ Connections  vertical organization  Types of cortex  Brodmann’s Areas  Cytoarchitecture and relation to function  Key Brodmann’s Areas  Major White Matter tracts of the Cerebral

cortex

 Internal Capsule 4

Descriptive Anatomy to function  Histological staining (Cell (overview) Bodies)  Discovered ??? arrangement of

the cortex  ??? are defined by cell type, size and density

 Broadman’s areas  Regions of the cortex have unique ???  Gave numbers to each of these ??? (Broadman’s areas)  Broadman’s areas and cortical

function

 Laminar layers have ???

correlates  Size of these layers are related

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Descriptive Anatomy to function  Histological staining (Cell (overview) Bodies)  Discovered laminar

arrangement of the cortex  Lamina are defined by cell type, size and density  Broadman’s areas  Regions of the cortex have unique laminar patterns  Gave numbers to each of these laminar patterns (Broadman’s areas)  Broadman’s areas and cortical

function

 Laminar layers have functional

correlates

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Cerebral Cortex – the Basic Ins and Outs  Afferent fibers

enter ???

 ??? process the

afferent information

 ??? fibers convey

the processed information to another site

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Cerebral Cortex – the Basic Ins and Outs  Afferent fibers

enter cortex

 Local circuits

process the afferent information

 Efferent fibers

convey the processed information to another site

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Cell Types and laminar locations: Local Circuit (interneurons) Local circuit neurons – AKA

Interneurons



interneurons, intrinsic neurons

???

???

 ??? do not leave the immediate

region of cell body, can cross into different laminar layers  Inhibitory, contain ??? (1 exception)

 Function – ???  Formulate rhythms, coordinate outputs  Interneurons classified by ???  ??? - Laver IV  ??? (have spines)  Receptive field II – IV  Excitatory (Glutamate)  ???(lack spines)  Receptive field mainly IV

 ??? –Layers III And V  Receptive field (all layers)  ???– Layer III

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output Aspiny

Spiny

???

Cell Types and laminar locations: Local Circuit (interneurons) Local circuit neurons – AKA 

Interneurons

interneurons, intrinsic neurons  Axons do not leave the

immediate region of cell body, can cross into different laminar layers  Inhibitory, contain GABA (1 exception)

Chandelie r cells

Stellate (granule) cells

 Function – regulate inputs to

and from pyramidal cells (cortical output cells)

 Formulate rhythms, coordinate

outputs

 Interneurons classified by

morphology

 Stellate (granule) - Laver IV  Spiny (have spines)  

Receptive field II – IV Excitatory (Glutamate)

 Aspiny (lack spines)  Receptive field mainly IV

 Basket –Layers III And V  Receptive field (all layers)

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output Aspiny

Spiny

Basket cells

Cell Types and laminar locations: Pyramidal (output neurons) Pyramidal cells: most inputs

 Pyramidal cells size by loci  Layer VI – ???; layer II&III – ???; layer V – ???  Layer VI pyramidal cells

inputs

???

 Inputs - Dendrites span layers ???  Outputs – ???

 Layer II & III pyramidal cells  Inputs – Dendrites span layers ???  Outputs – ???  Layer V pyramidal cells

inputs

???

???

 ??? (largest pyramidal neurons)

primary ??? (upper motor neurons)  Inputs – ???  Outputs –???, ???, ???, ??? 11

Corticocortical terminas

output

output output

Cell Types and laminar locations: Pyramidal (output neurons) Pyramidal cells: most  Pyramidal cells size by loci  Layer VI – small; layer II&III – small to medium; layer V – Large  Layer VI pyramidal cells

inputs

inputs

 Inputs - Dendrites span layers IV –

Medium

VI  Outputs – Thalamus, cortex, claustrum

 Layer II & III pyramidal cells  Inputs – Dendrites span layers I – IV  Outputs – Cortex opposite hemisphere (callosal)  Layer V pyramidal cells  Betz cells (largest pyramidal

neurons) primary motor cortex (upper motor neurons) 12

inputs

large

smal l Corticocortical terminas

output

output output

???? organization of cortex  Cortex is arranged

in ???  Run vertically (perpendicular to surface)  ~ 1 mm in diameter, containing 300 – 600 cells  Neurons in a column

synapse mostly with ???  ??? do connect near by columns

Pia surface

WM

 ??? is comprised of

billions of columns  Cortical columns are

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Vertical organization of cortex  Cortex is arranged in

functional columns  Run vertically

Pia surface

(perpendicular to surface)  ~ 1 mm in diameter, containing 300 – 600 cells

 Neurons in a column

synapse mostly with other cells in the column  Axon collaterals do connect near by columns

WM

 Cortex is comprised

of billions of columns  Cortical columns are quasi-independent processing units that

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Radial Glia and formation of ???? marginal zone cortical place

corticocorti cal bundles (CC) thalamic radiation (TR) nucleus basalis (NB) monoamine centers

subplate zone

Radial Glia Migration neuron

intermedi ate zone

ventricula r zone 15

Radial Glia and formation of Functional Columns marginal zone cortical place

corticocorti cal bundles (CC) thalamic radiation (TR) nucleus basalis (NB) monoamine centers

subplate zone

Radial Glia Migration neuron

intermedi ate zone

ventricula r zone 16

Columns and receptive fields  Each column is a ???  ??? specificity for each

column  i.e. a column may receive sensory input from rapidly adapting mechanoreceptor receptive field from the middle left fingertip (via spinal and thalamic pathways)  Adjacent columns may

pertain to ??? from the same region  i.e. a column adjacent to

RA = rapidly adapting receptive field i.e. epicritic(small filled circles) SA = slowly adapting receptive field i.e. protopathic (large open circles)

the one mentioned above may receive input fromcontains the ??? Column slowly adapting

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Columns and receptive fields  Each column is a single receptive field – single modality  Regional functional

specificity for each column  i.e. a column may receive sensory input from rapidly adapting mechanoreceptor receptive field from the middle left fingertip (via spinal and thalamic pathways)  Adjacent columns may

pertain to different modality from the same region

 i.e. a column adjacent to

RA = rapidly adapting receptive field i.e. epicritic(small filled circles) SA = slowly adapting receptive field i.e. protopathic (large open circles)

the one mentioned above may receive input from Column contains the microcircuitry for representing a single slowly adapting receptive field mechanoreceptor receptive

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???

Laminar organization: AfferentConnections

Glutamatergic Predominantly terminate in layer IV ???

???

Glutamatergic axons from

cortical regions outside of local circuit Terminate in layers I – VI, within a single cortical column

???

Origins: Non-specific

thalamic nuclei, basal nucleus of Meynert, Brain stem nuclei Substrates: glutamatergic, cholinergic, serotonergic, noradrogergic Terminates in layers I – VI, across multiple cortical columns

Haines

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Laminar organization: AfferentConnections Thalamocortical afferents

Glutamatergic Predominantly terminate in layer IV (thalamo-

receptive layer) Corticocortical afferents

Glutamatergic axons from

cortical regions outside of local circuit Terminate in layers I – VI, within a single cortical column

Diffuse cortical afferents

Origins: Non-specific

thalamic nuclei, basal nucleus of Meynert, Brain stem nuclei Substrates: glutamatergic,

Haines

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Laminar EfferentOrganization: Corticofugal/Corticothalamic Efferents Corticofugal Efferents  Pyramidal cells of ???  ??? targets  i.e. Corticospinal,

corticostriate, corticobulbar, cortico-tectal, corticopontine, etc.

Corticothalamic Efferents  ??? cells mainly in

layer ???

Corticothalamic

Haines

Laminar EfferentOrganization: Corticofugal/Corticothalamic Efferents Corticofugal Efferents  Pyramidal cells of layer V  Non-cortical

(subcortical) targets  i.e. Corticospinal, corticostriate, corticobulbar, cortico-tectal, corticopontine, etc.

Corticothalamic Efferents  Pyramidals cells

mainly in layer VI and V

Corticothalamic

Haines

Laminar EfferentOrganization: Corticocortical Efferents  Pyramidals cells mostly

located in layers ???  Axons project to distal cortical targets not ???  Terminate in layers ??? of a single cortical column  Cortical Targets in contralateral hemisphere are ??? connections  Tend to project to homologous

area in opposite hemisphere

 Cortical targets within same

hemisphere (ipsilateral)

Haines

Cortico-cortical: callosal & association

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Laminar EfferentOrganization: Corticocortical Efferents  Pyramidals cells mostly

located in layers II & II  Axons project to distal cortical targets (not local projections)  Terminate in layers I – VI of a single cortical column  Cortical Targets in contralateral hemisphere are Collosal (commissural) connections  Tend to project to homologous

area in opposite hemisphere

 Cortical targets within same

hemisphere (ipsilateral) are Association Connections

Haines

Cortico-cortical: callosal & association

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Major cortical connection from a gyrus

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Major cortical connection from a gyrus

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Cerebral Cortex Contains Regions Differing in Phylogenetic Development •??? (95%) • 6 layers • 1o sensory/motor, association area •Cognition, reasoning, perception, speech/language

•??? (5%) •??? •Up to 3 layers •Memory (e.g., hippocampus)

6 3

•??? • 4-5 layers • Smell/Emotion (e.g., olfactory ctx)

•??? function

Martin

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Cerebral Cortex Contains Regions Differing in Phylogenetic Development •Neocortex (95%) • 6 layers • 1o sensory/motor, association area •Cognition, reasoning, perception, speech/language

•Allocortex (5%) •Archicortex •Up to 3 layers •Memory (e.g., hippocampus)

6 3

•Paleocortex • 4-5 layers • Smell/Emotion (e.g., olfactory ctx)

•Limbic function

Martin

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Allocortex

Martin

6 layers

< 6 layers

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Allocortex

Martin

??? layers

< ??? layers

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Hippocampus – Allocortex structure R superior

Coronal section

L

Midsagitt al plane

inferi or

Parahippocampal gyrus of medial temporal lobe 31

???? – Allocortex structure

superior

Coronal section

R

L

Midsagitt al plane

inferi or

Parahippocampal gyrus of medial temporal lobe 32

Types of Neocortex: Homo- v Heterotypical Cortex  ??? Cortex  Each layer has about the same thickness  Representativ e of ??? cortex  ??? Cortex  Aberrant

thickness of one or more layers  Specific layers are over or under represented

Haines

IV: prominent V: narrow

V: prominent IV: narrow 33

Types of Neocortex: Homo- v Heterotypical Cortex  Homotypical

Cortex

 Each layer has

about the same thickness  Representativ e of association cortex  Heterotypical

Cortex

 Aberrant

thickness of one or more layers  Specific layers are over or

Haines

IV: prominent V: narrow

V: prominent IV: narrow 34

Cortical Cytoarchitecture: Brodann’s Areas Cortical divisions baseddiffering ? ??, defined by patterns of Nissl staining

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Cortical Cytoarchitecture: Brodann’s Areas Cortical divisions baseddiffering cytoarchitecture , defined by patterns of Nissl staining

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Brodmann's Areas •1ocortex

•2ocortex (sensory, motor)

•Unimodal 37

Brodmann's Areas •1ocortex

•2ocortex (sensory, motor)

•Unimodal 38

Brodmann's Areas •Higher motor cortex

•Association cortex

•Multi-modal

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Brodmann's Areas •Higher motor cortex

•Association cortex

•Multi-modal

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Brodmann’s Area (BA) of Cerebral Cortex

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Organization within Brodmann’s Areas Sensory and Motor homunculi ??? within primary cortex map body (M1, S1) ??? may represent different modalities from the same area (i.e. same

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Organization within Brodmann’s Areas Sensory and Motor homunculi Cortical columns within primary cortex map body (M1, S1) Adjacent cortical columns may represent different modalities from the same area (i.e. same receptive field on skin)

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Functional hemisheric ???of Higher cortical function •Speech: ??? hemisphere •Aphasia: speech disorders with ??? lesion

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Functional hemisheric asymmetry of Higher cortical function •Speech: left hemisphere •Aphasia: speech disorders with Left Hemisphere lesion (Frontal or Temporal/Parietal cortex)

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Right Parietal Association Cortex

???? Right (nondominant) parietal lesion  ??? syndrome: unaware of objects/events in left visual field  ??? – inability to draw maps – remember how they got to work  ??? – inability to duplicate spatial relations of individual parts of models  ??? – lack of •Neglect syndrome:with RH (parietal) lesion humor,

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Right Parietal Association Cortex Space and Attention Right (nondominant) parietal lesion  Neglect syndrome: unaware of objects/events in left visual field  Spatial surroundings deficits – inability to draw maps – remember how they got to work  Constructional apraxia – inability to duplicate spatial relations of individual parts of models •Neglect syndrome:with RH (parietal) lesion  Loss of affect –

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Major White Matter Tracts of Cerebral Cortex

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associationconnections: •Association connections •??? projections •Same lobe: adjacent regions •??? •??? •Different lobes •??? • WM tract interconnecting limbic lobe •??? •??? •Important in speech processing 49

associationconnections: •Association connections •Ipsilateral projections •Same lobe: adjacent regions •1o& 2o sensory cortex •Association regions •Different lobes •Cingulum (deep to cing. gyrus) • WM tract interconnecting limbic lobe •Uncinate fasciculus •Arcuate fasciculus •Important in speech processing 50

Digital Anatomist:Arcuate Fasciculus – Language coordination

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Digital Anatomist:Arcuate Fasciculus – Language coordination

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Internal Capsule Internal capsule

???

???

axial

???

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Internal Capsule Internal capsule

Thalamolenticular

Sublenticular

axial

Retrolenticular 54

InternalCapsule: Genu and Posterior limb descending projections

Thalamolenticular

axial

InternalCapsule: Genu and Posterior limb descending projections

Thalamolenticular

axial

Digital Anatomist: Corticobulbar/spinal

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Digital Anatomist: Corticobulbar/spinal

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InternalCapsule: Genu and Posterior limb ascending projections (Superior Thalamic Radiation)

Thalamolenticular

axial

InternalCapsule: Genu and Posterior limb ascending projections (Superior Thalamic Radiation)

Thalamolenticular

axial

InternalCapsule and Auditory radiations

Sublenticular

axial

Digital Anatomist: Somatosensory radiations

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Digital Anatomist: Somatosensory radiations

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Digital Anatomist: Auditory radiations

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Digital Anatomist: Auditory radiations

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InternalCapsule and Optic radiations

axial

Retrolenticular 66

InternalCapsule and Optic radiations

axial

Retrolenticular 67

Digital Anatomist: Optic radiations

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Digital Anatomist: Optic radiations

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END

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