Cerebral Cortex

Question 1

Neocortex

Answer 1

6-layered cortex, most extensive subtype of cortex

Question 2

Agranular cortex

Answer 2

motor (BA 4) and premotor (BA 6) cortex. poorly developed granule cell layers, prominent pyramidal cell layers –> OUTput

Question 3

granular cortex

Answer 3

sensory. receive INputs

Question 4

Layer 4

Answer 4

sensory signals. info traveling TO the cortex

Question 5

Layers 5 and 6

Answer 5

efferent cortical signals

Question 6

Layers 2 and 3

Answer 6

internal relay centers

Question 7

Distance rule

Answer 7

connections adhere more tightly to ascending-descending laminar pattern the more hierarchical levels they traverse

Question 8

Ascending pathway

Answer 8

first-order relay nucleus in thalamus –> layer 4 of primary cortical area

Bottom-up processing

Question 9

Descending pathway

Answer 9

feedback pathway. Layers 5 and 6 –> layers 6, 5 and 1 of lower area

Top-down processing

Question 10

mirror neurons

Answer 10

activated by the sight of an action performed by another individual, when it is congruent with the neuron’s own specificity in the production of that body movement

Question 11

premotor activity on primary motor cortex

Answer 11

represents motor concepts that might be translated into action by descending/modulatory input on M1

Question 12

output from motor cortex

Answer 12

layer 5 pyramidal cells

Question 13

outgoing component of thalamo-cortical loop

Answer 13

layer 6 neurons. does not directly influence behavior

Question 14

What produces electrical potential fluctuations measured by EEG?

Answer 14

temporal and spatial summation of electrical currents caused by the relatively slow postsynaptic potentials (EPSPs/IPSPs) induced in neurons of the cerebral cortex

Question 15

Where does the summation of electrical potential changes occur?

Answer 15

vertically oriented pyramidal cells

Question 16

Model of local field potential

Answer 16

synaptic excitation of vertically oriented layer 5 pyramidal cells –> inward cation flux –> relative negativity at the surface of skull

Question 17

Delta wave frequency

Answer 17

below 3.5 Hz

Question 18

Theta wave frequency

Answer 18

4-7.5 Hz

Question 19

Alpha wave frequency

Answer 19

8-13 Hz

Question 20

Beta wave frequency

Answer 20

14-30 Hz

Question 21

Gamma wave frequency

Answer 21

30-100 Hz

Question 22

What gives the oscillatory pattern seen in EEG waveforms?

Answer 22

synchronized activty of a large number of neurons in a given location

Question 23

Two methods of synchronicity in neuron firing

Answer 23

orchestra analogy:
conductor (thalamic reticular nucleus’ control over thalamocortical information flow) –> synchronized play;
group of musicians play the same melody (group of inhibitory interneurons discharging at the same time) –> other members join in (Self-organizing ensemble)

Question 24

Effect of Ach on thalamus

Answer 24

depolarizes thalamic relay neurons, inhibits thalamic reticular neurons –> opening of thalamocortical gate to sensory info

Question 25

What is the result of groups of inhibitory interneurons discharging at the same time

Answer 25

stronger inhibition on their targets --> more neurons silenced simultaneously --> increased probability of silenced neurons dicharging together upon recovery --> silence an even larger portion of population --> increased probability to fire together once inhibition stops

Question 26

What determines the frequency of oscillation with inhibitory neuron-induced synchrony?

Answer 26

duration of inhibition. fast-acting GABAa receptors --> gamma frequency oscillation

Question 27

neurons that fire together...

Answer 27

...wire together

Question 28

Effective connectivity

Answer 28

distant areas with synchronous oscillations may possess temporary windows in which they may communicate to a greater degree than other areas. Can be constructed based on synchrony observed in EEG, MEG, or fMRI