cerebral cortex 4/1

PI: which of the following cortical layers will be expanded if the sections as from the primary visual cortex?

1. layer I

2. layer II

3. layer III

4. layer IV

5. layer V

6. layer VI

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PI: which of the following layers chiefly gives rise to association and commissural fibers?

1. layer I

2. layer II

3. layer III

4. layer IV

5. layer V

6. layer VI

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association fibers

connect gyri within same hemisphere

PI: axons of this structure originate chiefly from which cortical layer?

1. layer I

2. layer II

3. layer III

4. layer IV

5. layer V

6. layer VI

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PI: which cortical area commands voluntary movements of the left forearm and shoulder?

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PI: which area is associated with voluntary movements of the right lower limb?

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PI: which area when damaged is associated with impairment of graphesthesia in the left hand?

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commissural fibers

connects gyri between two hemisphere (crosses midline)

PI: which area when damaged results in the following visual defect?

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PI: a 72 y/o woman is brought to the ER by her daughter. the history of the current event, provided by the daughter, reveals that the woman complained of a sudden headache and, after lying down for a period of time, seemed very confused. the examination reveals an otherwise healthy woman who can see but is unable to recognize what she sees, which is probably contributing to her apparent confusion. this woman is most likely suffering from which of the following?

1. aphasia

2. anopsia

3. agnosia

4. apraxia

5. akinesia

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PI: which area when damaged results in the ability to recognize someone else’s or one’s own face?

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PI: which area is associated with programming the production of spoken words?

3

PI: which area when damaged is associated with impaired ability to concentrate, easily distracted, loss of initiative, apathy, cannot make decisions?

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cerebral cortex

“highest center”

perceives sensations, commands skilled movements (UMNs), provides awareness of emotions and behavior (limbic system), necessary for memory and thinking (cognition), language abilities

older parts of the cerebrum

archicortex (found in hippocampus)

paleocortex (pyriform cortex) anterior to ^

neocortex

makes up 90% of cerebral cortex

6 histological layers

ex. primary motor cortex, primary visual cortex

layer 1 of neocortex

molecular layer

just deep to surface of cerebral cortex is (meningeal layer)

mostly devoid of neurons

some left to right myelinated axons

neighboring cortical columns have synapses

layer 2 of neocortex

external granular cell layer

interneurons with short axons

layer 3 of neocortex

external pyramidal cell layer

large pyramidal neurons

association fibers to white matter within same hemisphere, synapse on a cortical column in layers 2 & 3

commissural fibers to white matter, cross midline, synapse on cortical columns in layers 2-4

layer 4 of neocortex

internal granular cell layer

receptive in nature

input primarily from thalamus (corticopetal axons)

very thick in sensory cortex

layer 5 of neocortex

internal pyramidal cell layer

output layer

axons projects away from cortex (corticofugal)

thick in motor cortex, thin in sensory cortex

layer 6 of neocortex

multiform layer

various interneurons of various shapes

output layer (projection fibers to thalamus)

granule cells

chief input neurons of cortex

pyramidal cells

chief output neurons of cortex

functional/physiological arrangement of cerebral cortex

cortical columns

0.5-1mm wide

all neurons within a column work collectively for one particular function

cortical columns with the same function may not be adjacent to one another

frontal lobe

anterior to central sulcus

deep to frontal bone

parietal lobe

posterior to central sulcus

temporal lobe

inferior to lateral fissure

occipital lobe

posterior part of brain

brodman’s cortical areas

based on the thickness of different areas of the cerebral cortex

primary (unimodal) areas

processes single functions—primary motor cortex commands movements

association (polymodal) areas

integrates more than 1 function—parietal association integrates somatosensory, visual, hearing

PI: a 72 y/o man presents with severe weakness of his R lower limb but has age-appropriate strength in both of his upper limbs. which of the following (pictured) might be the location of the lesion?

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PI: a 67 y/o female patient is brought to the ER after her daughter noticed she has been having meaningless speech. when assessing the patient, she calls the chair a table, and at times would make up new words. she does not appear to be aware of her deficit and is carrying on an empty conversation. her speech is fluent, but with paraphasic errors. her repetition is impaired. on physical examination, a right upper quadrant field-cut is appreciated, with impairment in comprehension and repetition. which of the following (pictured) structures is most likely involved int his patient’s presentation?

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PI: a 66 y/o retired cartoonist with some reluctance was brought to the family physician by his wife who was “terribly concerned” about his recent behavior. she stated that her husband didn’t seem to know what to do with himself anymore. although his wife found this behavior tolerable since he was “getting old”, she became frightened by another peculiarity of his which was to go to bed leaving on his left shoe and sock. he would also leave on half of his shirt and trousers (left side). his left arm and leg were always seen to be hanging off the side of the bed. one night, she undressed his left side after he went to sleep only to discover that he refused to redress his left side when he got up the next morning. a scan reveals a cortical infarct. which of the following (pictured) structures is most likely involved in this patient’s presentation?

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