Cortex

Question 1

how many layers in the isocortex? allocortex?

Answer 1

6 (neocortex), 3 layers (paleocortex and archicortex)

Question 2

molecular layer

Answer 2

layer 1. not many cell bodies, mostly axon/dendrite

Question 3

external granular layer

Answer 3

layer 2

Question 4

external pyramidal layer

Answer 4

layer 3

Question 5

supregranular layers

Answer 5

layers 1 2 3

Question 6

granular layer

Answer 6

layer 4- 3 distinct sub bands

Question 7

internal pyramidal layer

Answer 7

layer 5

Question 8

fusiform layer

Answer 8

layer 6

Question 9

infragranular layer

Answer 9

layets 5/6

Question 10

3 groups of neurons

Answer 10

spiny stellate- central cell body w/ dendrites radiating in all directions. found in layer 4. excitatory- use glutamate. project to layer 2/3 primarily

pyramidal- triangular soma. have basal and oblique dendrites. pointing towards 1st layer. excitatory- use glutamate. found in layers 2/3, 5, 6. relative output is down

nonpyramidal- inhibitory. all layers. 20% of cortical neurons. use GABA. non-spiny dendrites

Question 11

not all pyramidal cells project to the same cell types

Answer 11

ok

Question 12

feed forward inhibition vs feedback inhibition

Answer 12

excitatory cell activates inhibitory cell, which inhibits downstream

excitatory cell is inhibited by the inhibitory cell it is exciting

Question 13

cortical circuit

Answer 13

1. thalamic input to layer 4 SS cells
2. SS cells project to P cells in layer 2/3

3 P cells in layer 2/3 are highly connected to layers 5/6

4 layers 5/6 P cells provide majority of cortical output

5 feedforward and feedback inhibition shape the flow of excitatory activity

Question 14

cost/benefit of excitatory synapse

Answer 14

benefit- extensive connectivity and plasticity- learning, memory, cognition

cost- excitotoxicity

Question 15

how to protect vs excitotoxicity

Answer 15

block excitation, enhance inhibition, limit APs

Question 16

expectation vs reality

Answer 16

2 groups of dendrites- apical tufts vs oblique and basal dendrites- receive input from different places

“bottom up” sensory info arrives from thalamus to middle layers- new data- causes steady, low frequency bursts

top down info from association cortex to apicl tufts- predictions- causes very infrequent high frequency busrsts

both together create sustained bursts

Question 17

columnar structure of cortex

Answer 17

vertical arrangements of neurons processing similar types of info form functional modules