Cerebrum Flashcards

1
Q

Define the three types of mammalian cortex

A
  1. Archicortex (3 layers, hippocampus)
  2. paleocortex (3-5 layers, olfactory/pyriform cortex)
  3. neocortex (6 layers, everything else)
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2
Q
A
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3
Q

What are the major principle cells of cerebral cortex?

A
  1. Pyramidal cells (excitatory, 2/3 of all neurons, glutamatergic)
  2. Fusiform cells (atypical, irrgular, elliptical)
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4
Q

What are the major interneurons in the cerebral cortex?

A
  1. Stellate (excitatory, layer IV, star)
  2. Basket cell (inhibitory, lateral branching axons)
  3. Retzius-cajal cells (aka horizontal cells, molecular layer)
  4. Cells of martinotti (deep layers, axons project up to plial layer)
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5
Q

What are the 6 layers of cortex & the cells found in each

A
  1. Molecular
    * synaptic layer, retzius-cajal cell bodies, terminal dendrites/axons, pyramidal dendritic branches)
  2. External Granular
    * small pyramidal & interneurons
  3. External Pyramidal
    * small/medium pyramidal (forms association & commissural fibres)
  4. Internal Granular
    * stellate, some other interneurons & pyramidal
  5. Internal Pyramidal
    * large pyramidal (form projection fibres)
  6. Multiform
    * cells of martinotti, fusiform, few interneurons, pyramidal cells that project to thalamis/claustrom
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6
Q

Describe some of the variations in cytoarchitecture and how they can be used to identify different regions of the cerebrum

A
  • primary visual, auditory and somatosensory cortex (layers 2-5 merge into one)
  • Primary motor & premotor (layers 2-6 merge into one)
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7
Q

Describe the organisation of intracortical circuits.

A
  • Cortical cell axons excite pyramidal apical dendrite
  • input from thalamus excites pyramidal basal dendrites & stellate cells
  • stellate cells excite pyramidal cells
  • input from thalamus & pyramidal cells excite basket cells
  • basket cells inhibit currounding pyramidal cells
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8
Q

Describe and identify the cerebral localisation and circuitry of general somatic sensation

A

Primary somatic = Brodman 1,2,3 (postcentral gyrus)
* input from ventral posterior thalamus
* homunculus (localisation of sensation)

Somatic association = Areas 5&7 (superior parietal lobule & precuneus)
* input from primary somatic, lateral posterior thalamus and pulvinar
* allows object recognition without visual aid

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9
Q

Describe and identify the cerebral localisation and circuitry of vision

A

Primary visual = area 17 (surrounding calcarine sulcus)
* input form lateral geniculate thalamus via geniculocalcarine tract
* LHS visual field represented in RHS brain (and vice versa)

Visual association = areas 18 & 19 (occipital surrounding primary area)
* input from contralateral area 17, thalamus & pulvinar
* complex visual processing, recognition & significance

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10
Q

Describe and identify the cerebral localisation and circuitry of hearing

A

Primary auditory = areas 41 & 42 (ventral wall of lateral sulcus, herschl’s convolutions)
* input from medial geniculate thalamus

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11
Q

Describe and identify the cerebral localisation and circuitry of taste

A

Taste = Area 43 (inferior postcentral gyrus)
* input from medial ventral posterior thalamus

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12
Q

Describe and identify the cerebral localisation and circuitry of olfaction

A

Olfactory = Area 34 (limen insulae & uncus)
* input from olfactory tubercle & medial dorsal thalamus

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13
Q

Describe and identify the cerebral localisation and circuitry of vestibular

A

No defined cortical area.
* intraparietal sulcus (in somatosensory cortex) & posterior insular
* integrates vestibular & proprioceptive signals

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14
Q

Describe and identify the cerebral localisation and circuitry of motor systems

A

Primary moto = area 4 (precentral gyrus)
* input from other motor cortex, posterior ventral lateral thalamus

Supplementary/cingulate motor
* area 6 (PMA/SMA) & anterior cingulate
* Area 8 frontal eye fields for control of eye movements.
* input from many cortical areas, ventral anterior thalamus & ventral lateral thalamus

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15
Q

Identify the localisation of language areas that control both comprehension of language and motor speech areas.

A

Wernicke’s Area
* Area 22 - Left posterior superior temporal gyrus
* receptive language area - comprehension of spoken and written language

Broca’s area
* Areas 44 & 45 - inferior frontal gyrus
* expressive speech area - motor speech

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16
Q

What are the 3 types of cerebral fibre tract?

A
  1. Association tracts (within 1 hemisphere)
  2. Commissural tracts (between 2 hemispheres
  3. Projection tracts (between cortical & subcortical, ie internal capsule)
17
Q

Identify the major association fasciculi and their connections.

A
  1. Cingulum - cingulate gyrus, parahippocampal gyrus & septum
  2. superior longitudinal fasciculus - parietal, temporal, occipital lobes to frontal lobe
  3. superior occipitofrontal fasciculus - anterior frontal and posterior frontal cortex
  4. inferior occipitofrontal fasciculus - orbital frontal cortex and temporal lobe
18
Q

Identify the major commissural tracts and their connections.

A
  1. Corpus callosum (enourmous, majority of neocortical fibres)
  2. anterior commissure (additional comms between paleocortical temporal lobes)
19
Q

Identify the major projection fibres and their connections.

A

all travel along internal capsule
1. thalamic radiations (between thalamus and cortex)
2. motor (corticofugal) - (from motor cortex to basal ganglia, cerebellum & spinal tracts)

20
Q
A