Cerebral Cortex

Question 1

three types of cerebral cortex

Answer 1

neocortex: most of cortex, 6 layers (isocortex, homogenic cortex)
paleocortex: 3 layers, uncus, olfaction
archiocortex: 3 layers, most of hippocampus (allocortex, heterogenic cortex)

Question 2

cell types of neocortical neurons

Answer 2

1. pyramidal cells: long axons

2. nonpyramidal cells: short axons, remain in cortex

Question 3

pyramidal cells

Answer 3

1. apical dendrite: one/cell, extend to top layer of cortex
2. basal dendrites: several/cell, extend horizontally in respective layer (axons have recurrent brs, excite neighboring pyramidal cells)

Question 4

pyramidal cell synapses

Answer 4

• excitatory (glutamate) synapses
• principle projection neurons of cortex
• dendritic spines: preferential site of excitatory synapses

Question 5

nonpyramidal cells

Answer 5

• diverse
• mostly inhibitory (GABA) synapses
• principle interneurons of cortex
• 3 cell types

Question 6

cell types of nonpyramidal cells

Answer 6

1. spiny stellate cells: excitatory, synapse w/ pyramidal cells
2. smooth stellate cells: receive recurrent collateral brs from pyramidal cells, inhibitory
3. bipolar cells: located in outer layers, contain peptides co-released with GABA

Question 7

cortical laminar organization

Answer 7

(apical)
1. molecular
2. outer granular
3. outer pyramidal
4. inner granular
5. inner pyramidal
6. fusiform 
(basal)

Question 8

how is granular and agranular cortex distributed?

Answer 8

irregularly

Question 9

afferents to cortex

Answer 9

1. association fibers: from small/med pyramidal cells in other parts of ipsilateral cortex
2. commissural fibers: med pyram cells cia corpus callosum or ant comm from same contralat cortex
3. thalamocortical fibers: from relay or assoc nuclei
4. non-specific thalamocortical fibers: from intralaminar nuc
5. cholinergic and aminergic: from basal forebrain, hypothalamus, BS

Question 10

efferents from cortex

Answer 10

• all are pyramidal cell axons and all are excitatory
  1. short assoc: sensory cortex->motor cortex
  2. long assoc: prefrontal cortex->motor cortex
  3. commissural fibers: prefrontal cortex->motor cortex

Question 11

fibers from where make up largest input to BG

Answer 11

primary sensory and motor cortex

Question 12

where does thalamus receive input from

Answer 12

all of cortex

Question 13

commissures

Answer 13

• interconnect cerebral hemispheres
  1. corpus callosum: predominant interconnection btwn hemis, largest bundle of fibers in brain
  2. ant commissure: interconnects temporal lobes, ant olfactory nuc

Question 14

disconnection syndromes

Answer 14

• can result from white matter damage
• alexia w/o agraphia (can write but not read)
• L visual cortex damaged, speech uneffected

Question 15

association bundles

Answer 15

• interconnect areas of 1 hemi
• short: U shaped fibers
• long: travel to diff lobes
  1. sup long (arcuate) fasciculus)
  2. sup occipitofrontal fasciculus
  3. inf occipitofrontal fasciculus
  4. cingulum, uncinate fasciculus

Question 16

neocortical regional specialization

Answer 16

• agranular primary motor cortex precentral gyrus (more pyramidal cells)
• granular somatosensory cortex post central gyrus

Question 17

types of cortical regions

Answer 17

1. primary motor areas: give rise to much of corticospinal tract
2. primary sensory areas: receive info from thalamic sensory relay nuclei
3. assoc areas: pulvinar and dorsomedial
4. limbic areas

Question 18

homonculus

Answer 18

sensory areas have topographical organization where body surface, range or frequencies, and visual world are mapped on cortical surface

Question 19

parietal lobe fnctns

Answer 19

-primary somatosensory cortex: post central gyrus (initial processing of tactile and proprioceptive info)

Question 20

occipital lobe fnctns

Answer 20

• primary visual cortex, in banks of calcarine sulcus
• visual assoc cortex: higher order visual processing
• visual fields

Question 21

what does a bilateral injury to inf occipital lobe cause

Answer 21

color blind

Question 22

what does a bilateral injury to occ-temp jnctn cause

Answer 22

motion blind

Question 23

visual fields

Answer 23

fibers from: nasal 1/2 of retina cross to contralat optic tract, temp 1/2 enter ipsilat optic tract

Question 24

LGN structure

Answer 24

• 6 layered, precise retinoptic arrangement, pattern same in each layer
• each layer gets input from 1 eye, 1, 4, 6=contralat
• layers 1-2:magnocellular (movement and contrast)
• layers 3-6: parvocellular (color and form)
• projects to primary visual cortex

Question 25

role of cortex in vision

Answer 25

• primary visual cortex
  1. breaks visual info into component parts
  2. distributes this info into specialized parts of extrastriate cortex
• simultaneous, parallel processing

Question 26

dorsal and ventral streams of visual info

Answer 26

• process starts in LGN
• parvocellular layers (ventral stream): color, form
• magnocellular layers (dorsal stream): location, movement

Question 27

temp lobe fnctns

Answer 27

• primary audotory cortex (transverse temp gyri sup surface of sup temp gyrus)
• auditory assoc cortex
• lang comprehension (wernickes area: post aspect of L hemi)
• higher order visual processing

Question 28

gustatory and vestib cortex

Answer 28

• gustatory: frontal lobe, operculum and insula

vestib: sup temp gyrus and post insula

Question 29

olfactory cortex

Answer 29

-primary olfactory cortex is paleocortical

Question 30

frontal lobe

Answer 30

• brocas areas: inf frontal gyrus of usually L hemi->spoken and written lang
• prefrontal cortex: rest of frontal lobe, executive fnctns
• primary motor cortex in precentral gyrus

Question 31

association areas

Answer 31

• mediate higher mental fnctns (lang, art, music)
• 2 types
  1. unimodal: adjacent to primary area, devoted to elaborating on business of primary area
  2. multimodal: high level of intellectual fnctns (inf parietal lobe, much of frontal and temp lobes)

Question 32

2 types of aphasia

Answer 32

1. nonfluent: few written/spoken words, get by with phrases, can comprehend lang-> brocas aphasia
2. fluent: can write and speak words, but difficulty in language comprehension->wernickes aphasia

Question 33

damage to brocas area

Answer 33

• deprive motor areas and ability to generate language

- comprehension of lang uneffected

Question 34

damage to wernickes area

Answer 34

words are generated but no meaning

Question 35

language in R hemi

Answer 35

• emotional content
• prosody (inf frontal gyrus)
• R post temporoparietal region comprehends prosody

Question 36

parietal cortex

Answer 36

• assoc areas post to primary somatosensory cortex
• unimodal areas: visual accos cortex, auditory assoc areas, somatosensory
• multimodal areas: centered on intraparietal sulcus

Question 37

R parietal lobe damage

Answer 37

• pt has trouble w/ L 1/2 of body

- many deny anything is wrong

Question 38

L parietal lobe damage

Answer 38

• imp for taking sensory info needed to plan a movement accurately
• apraxias (lack of action)

Question 39

prefrontal cortex

Answer 39

• controls activities on other cortical areas, underlies executive fnctns
• interconnected with DM nucleus of thalamus

Question 40

2 types of prefrontal cortex

Answer 40

1. DL (over lat convexity)
   - imp role in working mem, problem planning, solving problems
2. VM (extends to orbitofrontal and ant cingulate areas)
   - damage make people impulsive, cant suppress inappropriate responses/emotions