Lec 54 Cerebral Cortex

Question 1

What is the allocortex?

Answer 1

division of cerebral cortex containing:

• archicortex [hippocampus]
• paleocortex [parahippocampal]

Question 2

What is isocortex?

Answer 2

division of cerebral cortex = the neocortex

Question 3

What are the 5 major neocortical afferents?

Answer 3

• thalamus
• neocortex
• amygdala
• parahippocampal areas
• diffuse NT projects [extrathalamic]

Question 4

What is the function of neocortical afferents from the thalamus? where do efferents back to thalamus come from?

Answer 4

afferents from thalamus: initial representation of topographic maps, nuclei linked to regions

efferents to thalamus: reciprocal projects from layer 6

Question 5

What is the function of neocortical afferents from the neocortex? what about efferent back to neocortex?

Answer 5

afferents from neocortex: cortico-cortical circuits

efferents to neocortex: reciprocal cortico-cortical circuits

Question 6

What is the function of neocortical afferents from the amygdala? where do efferents back to amygdala come from?

Answer 6

afferents from amygdala: emotional tone to neocortex function

efferents to amygdala: from primary prefrontal and cortex

Question 7

What is the function of neocortical afferents from the parahippocampal areas? where do efferents back to parahippocampal areas come from?

Answer 7

afferents from parahippocampal areas: role in memory

efferents to parahippocampal areas: from association cortex

Question 8

What is the function of neocortical afferents from the extrathalamic diffuse projectiosn?

Answer 8

MOA/ACh neurons, regulate mood, attention

Question 9

Where do amygdala afferents project to in neocortex?

Answer 9

project to prefrontal cortex [PFC], temporal lobe

Question 10

What are the major neocortical efferents?

Answer 10

1. to thalamus: reciprocal from layer 6
2. to neocortex: reciprocal
3. to amygdala: from primarily prefrontal + temporal
4. to parahippocampal from association cortex
5. to brainstem: pons, motor nuclei, tectum
6. spinal cord

Question 11

Which layer of neocortex receives input from thalamus? which projects back?

Answer 11

layer 4 = receives input

layer 6 = projects back

Question 12

What is unique about laminar structure of V1?

Answer 12

• highly elaborated layer IV for thalamic input [3 sublayers]
• small V that projects to brainstem

Question 13

What is unique about laminar structure of V2?

Answer 13

• extra layer of pyramidal cells that V1 doesn’t have = characteristic of an association cortex

Question 14

What is unique about laminar structure of M1?

Answer 14

• elaborated layer V with betz cells = motor output to distal digits
• no layer IV

Question 15

What are the classic output layers? classic input layers?

Answer 15

classic output = 5, 6

classic input = 4

Question 16

What is structure of 3 layer 4 sublayers in V1?

Answer 16

4a and 4c = stellate, receive thalamic input

4b = pyramidal cells

Question 17

What is function of pyramidal neuonrs?

Answer 17

• principle output neurons
• excitatory [glutamate]
• regulated by interneurons
• spiny

Question 18

What output pyramidal neurons in each of layers 2, 3, 5, and 6?

Answer 18

layer 2/3 = cortical-cortical
layer 5 = to striatum, brainstem, spinal cord
layer 6 = to thalamus

Question 19

What are 3 types of inhibitory interneurons in cerebral cortex?

Answer 19

double bouquet = modulating, synapse distally
basket cells = wrap cell body, implicated in epilepsy
chandelier = most powerful, wrap axon hillock

Question 20

What are spiny stellate interneurons?

Answer 20

excitatory interneurons

• only in layer IV of S1 V1
• receive input from thalamus

Question 21

Where are the pyramidal neurons associated with ALS?

Answer 21

loss of brainstem and spinal cord pyramidal neurons in layer 5

Question 22

Where are the pyramidal neurons associated with Alzheimer’s?

Answer 22

loss of cortical cortical projections in layers 2, 3, 5

Question 23

What are the 4 types of extrathalamic subcortical afferents to the neocortex?

Answer 23

1. NA from locus coerulues in pons
2. 5HT from dorsal raphe in midbrain
3. DA from VTA in midbrain
4. ACh from nucleus basalis

*go to all layers of neocortex

Question 24

What types of circuits are glutamate neurons linked to?

Answer 24

corticocoritcospinal and cortex-thalamic circuits

Question 25

What circuits are GABA neurons linked to?

Answer 25

local interneurons

Question 26

What circuits are MOA/ACh linked to?

Answer 26

global, diffuse modulation throughout cortex