Cerebral Cortex

Question 1

What is the average thickness of the gray matter of the cortex?

Where is it thickest and thinnest?

Answer 1

2.5mm

Range:

1. 5mm at the occipital cortex
2. 5mm at the primary motor cortex

Question 2

What are the 3 types of cortices?

Answer 2

1. Isocortex: 6 layers– primary sensory and motor cortex
2. Mesocortex (Paleocortex, Archicortex): Intermediate– cingulate gyrus, parahippocampal cortex
3. Allocortex: 3 layers– primary olfactory cortex and hippocampal formation

Question 3

What is the only cortical layer without pyramidal neruons?

Answer 3

1

Question 4

What are the types of principal neurons?

How about interneurons?

Answer 4

Pyramidal and Fusiform

Stellate or granule cells, Horizontal Cells of Cajal, Cells of Martinotti

Question 5

What is the only excitatory interneuron?

Answer 5

Stellate or granule neuron– Secretes glutamate

ALL OTHERS ARE GABA SECRETING

Question 6

The neurons of all six layers of the cortex develop in waves from?

When are they first recognizable?

Answer 6

The periventricular germinal matrix

All six layers are recognizable by 7 months of intrauterine life

Question 7

What cortical layer?

1. Are the stripes of Kaes-Bekhterev found
2. Stripe of Gennari and band of baillarger
3. Main recepient of the thalamocortical fibers
4. Lowest cell packing density and location of the BEtz cells
5. Internal band of Baillarger
6. Cells of Martinotti are prominent here

Answer 7

1. Layer 3 External pyramidal
2. Layer 4 IN THE VISUAL CORTEX– hence the name striate cortex!
3. Layer 4 Internal Granular
4. Layer 5 Internal Pyramidal
5. Layer 5 Internal pyramidal layer– these are form thalamic sensory nuclei thus the band IS MOST PROMINENT IN PRIMARY CORTICAL SENSORY AREAS
6. Layer 6 Multiform layer

Question 8

What cortical layer/s?

7. Present in all types of cortex
8. Present in neocortex
9. Mainly receptive
10. Mainly efferent

Answer 8

7. 1 5 6
8. 2 3 4
9. 1 2 3 4
10. 5 6

Question 9

Where do these monoaminergic inputs mainly come from

1. Serotonergic
2. Dopaminergic:
3. Noradrenergic input
4. Cholinergic input

Answer 9

1. Serotonergic: Raphe nuclei in them midbrain and pons– role in pain control, sleep and emotion
2. Dopaminergic: Ventral tegmental area of tsai and the substantia nigra of the mesencephalon– role in orienting behavior
3. Noradrenergic input: Locus ceruleus in the rostral pons– arousal state
4. Cholinergic input: Nucleus basalis of Meynert– arousal and motivation

Question 10

Which association fiber is being described?

1. Connects the atnerior perforated substance with the parahippocampal gyrus
2. Connects the frontal lobe with the parietal occipital and temporal lobes
3. Sweeps around the insula to connect the inferior frontal area (broca) with the superior temporal gyrus (wernicke)
4. Connects adjacent regions of the occipital and temporal areas
5. Connects the inferior frontal gyrus with the anterior temporal lobe

Answer 10

1. Cingulate fasciculus: Connects the atnerior perforated substance with the parahippocampal gyrus
2. Superior longitudinal fasciculus: Connects the frontal lobe with the parietal occipital and temporal lobes
3. Arcuate fasciculus: Sweeps around the insula to connect the inferior frontal area (broca) with the superior temporal gyrus (wernicke)
4. U fibers: Connects adjacent regions of the occipital and temporal areas
5. Uncinate fasciculus: Connects the inferior frontal gyrus with the anterior temporal lobe

Question 11

What are the commisural fiber systems?

Answer 11

Corpus callosum
Anterior commissure
Hippocampal commissure

Question 12

Which areas of the cortex innervate the lower subnucleus of the nuclei of CN7 of the contralateral side?

How about those that go to both upper subnuclei?

Answer 12

1. Primary motor cortex, caudal cingulate gyrus

2. Supplementary motor cortex, rostral cingulate gyrus

Question 13

Which parts of the cortex subserve EMOTIONAL expresssion?

Answer 13

Cingulate gyrus

Question 14

Identify the Brodmann area:
Post central gyrus
Precentral gyrus
Primary visual cortex
Superior temporal gyrus, auditory association area (Wernicke’s)
Heschl’s gyrus, primary auditory cortex
Pars opercularis of the inferior frontal gyrus
Pars triangularis of the inferior frontal gyrus
BOTH form the Broca’s area
Dorsal entorhinal area for olfaction, medial most temporal lobe
Insular cortex Island of Reil, frontoparietal rolandic operculum, gustatory cortex

Answer 14

Post central gyrus 1,2,3
Precentral gyrus 4
Primary visual cortex 17
Superior temporal gyrus, auditory association area (Wernicke’s) 22
Heschl’s gyrus, primary auditory cortex 41 42
Pars opercularis of the inferior frontal gyrus
Pars triangularis of the inferior frontal gyrus
BOTH form the Broca’s area 44 45
Dorsal entorhinal area for olfaction, medial most temporal lobe 34
Insular cortex Island of Reil, frontoparietal rolandic operculum, gustatory cortex 43

Question 15

What is the most medial representation in the sensory homunculus

Answer 15

Anal and genital regions

Question 16

Which brodmann areas are activated by different sensory stimuli?

Answer 16

1 both cutaneous or proprioreceptive
2 and 3a Proprioreceptive
3b cutaneous

Question 17

What do lesions in the primary somatosensory association areas in the the superior parietal lobule B5 and 7 do?

Answer 17

Bilateral: Optic ataxia– unable to move hand toward an object that is seen
Unilateral: Neglect of the opposite side of the body

Question 18

Why would a PCA infarct still have macular sparing?

Answer 18

Because of the collateral supply from the MCA to the macular area of the cortex

Question 19

What are the dorsal and ventral stream outputs from the visual cortex?

Where do they go and what are they for?

Answer 19

Dorsal to the occipitoparietal cortex for the “where” pathway– lesion Balint Holmes syndrome inability to direct eyes ta certain point despite having intact eoms

Ventral to the occipitotemporal cortex for the “what” pathway– lesion visual agnosia inability to comprehend the meaning of nonverbal visual stimuli

ADD: Bilateral lesion in the inferior parietal lobule will cause Balint syndrome (Optic ataxia, oculomotor ataxia and psychic paralysis of visual fixation)

Question 20

Stimulation of the primary auditory cortex results in?

Lesions there result in?

Answer 20

Tinnitus

Impairment in sound localization in space with diminution of hearing bilaterally

Question 21

What is the function of Area 22 on the non-dominant hemisphere? Wernicke’s on the dominant side

Answer 21

Specializes in non speech auditory information: prosody– tonal qualities of sound, musical melodies

Question 22

Where is the primary vestibular cortex?

Answer 22

lateral cortical temporoparietal area
B40 Supramarginal gyrus
B21 Middle temporal gyrus
B22 Superior temporal gyrus

Question 23

What percentage of fibers in the corticospinal pyramidal tract is from the primary motor cortex? Originate directly from the giant motor neurons of Betz?

Answer 23

40%

3%

Question 24

What is the function of the supplementary motor are? What percentage contributes to the pyramidal tract?

Answer 24

Sequential performance of multiple movements

5%

Question 25

What apraxia results from destruction of the premotor area?

Answer 25

Ideomotor apraxia Ideomotor apraxia: These patients have deficits in their ability to plan or complete motor actions that rely on semantic memory. They are able to explain how to perform an action, but unable to "imagine" or act out a movement such as "pretend to brush your teeth" or "pucker as though you bit into a sour lemon." Contrast with ideational apraxia: Ideational/conceptual apraxia: Patients have an inability to conceptualize a task and impaired ability to complete multistep actions. Consists of an inability to select and carry out an appropriate motor program. For example, the patient may complete actions in incorrect orders, such as buttering bread before putting it in the toaster, or putting on shoes before putting on socks. There is also a loss of ability to voluntarily perform a learned task when given the necessary objects or tools.

Question 26

Besides the FEF what other cortical area is concerned with smooth pursuit?

Answer 26

Temporooccipitoparietal cortex

Question 27

What percentage of left handed people will be left dominant?

Answer 27

2/3

Question 28

Besides the posterior portion of the superior temporal gyrus what is the other part of Wernicke's area not originally described by the founder?

Answer 28

Angular gyrus B39 While 22 is for comprehension of spoken language 39 is for written language

Question 29

What connects the Broca's and Wernicke's areas?

Answer 29

Arcuate fasciculus

Question 30

Where is Broca's area?

Answer 30

Posterior part of the triangular gyrus B45 and the opercular gyrus B44 in the inferior frontal gyrus

Question 31

Lesion of "Broca" B44 in right will result in? "Wernicke" B22 in right?

Answer 31

Dull monotonous speech Unable to detect inflections in speech

Question 32

The lesioned area in patients with the Gerstmann sydnrome is in the major association cortex. Where is this?

Answer 32

Inferior parietal gyrus on the dominant side Supramarginal gyrus B40 Angular gyrus B39

Question 33

What are the five major branches of the anterior cerebral artery?

Answer 33

``` Oribitofrontal branch Frontopolar branch Pericallosal branch --Callosomarginal branch --Paracentral branch ``` -- branches of the pericallosal branch

Question 34

What connects the vein of Trolard and the vein of Labbe?

Answer 34

The middle cerebral vein

Question 35

Broca's aphasia patients speak in 10 words or less per minute with paraphasia. What are paraphasias?

Answer 35

Ommission of phonenmes or substitution of incorrect phonemes. Pem for pen Ha for hall NOTE THAT PARAPHASIA ALSO OCCURS IN WERNICKE'S

Question 36

Differentiate transocortical sensory from Wernicke's.

Answer 36

TS can repeat! But both have problems with auditory comprehension

Question 37

Where is the lesion in conduction aphasia?

Answer 37

Posterior perisylvian area-- can understand and speak but CANNOT REPEAT Interrupts the arcuate fasciculus

Question 38

Where is the lesion in anomic aphasia?

Answer 38

Inferior or anterior temporal

Question 39

Thalamic lesions have what type of aphasia?

Answer 39

Similar to broca's While left basal ganglia have fluent, paraphasic and dysarthric speech-- similar to Wernicke's

Question 40

What are the three anatomic locations of ideomotor apraxia?

Answer 40

Parietal Sympathetic Callosal

Question 41

What is ideational apraxia?

Answer 41

Abnormality in the conception of movement so that the patient may have difficulty sequencing the different components of a complex motor act-- such as in mailing a letter

Question 42

What is alexia and where are the lesions?

Answer 42

Inability to comprehend written language Without agraphia-- left PCA infarcts With agraphia-- dominant angular gyrus

Question 43

What are the three findings in Balint syndrome?

Answer 43

Ocular apraxia Ocular ataxia Simultagnosia

Question 44

What are the 6 elements of Kluver Blucy Syndrome? (With temporal lobectomy)

Answer 44

1. Blunted affect 2. Psychich blindness or visual agnosia 3. Hypermetamorphosis: Urge to notice everything in sight 4. Hyperorality 5. Bulimia 6. Alteration in sexual behaviour

Question 45

How to test for simultagnosia? A component of Balint's syndrome

Answer 45

Show them a detailed picture. They will get the details right but they will be unable to get the meaning of the entire picture

Question 46

Lesion in alien hand syndrome?

Answer 46

1. Corpus callosum | 2. Medial frontal lesion including the supplementary motor area