Cerebral cortex

Question 1

why do neurons have channels that spontaneously open

consequences

Answer 1

so they can respond when needed

may create aberrant AP

thus cells may discharge in absnece of stim or not fire with stim

Question 2

trade off between fidelity and energy consumptom

Answer 2

neuron = decr fidelity because decr energy consumptom

decr energy because so small

therefore signal must be boosted above general background noise

Question 3

how to distinguish signals from noise

Answer 3

multiple neurons encode signal

top down inference = using previous experience to determine what signal means (if noisy input, higher neurons will weigh signal appropriately)

Question 4

what is bottom up flow

Answer 4

feed forward

layer 3 –> higher layer 4 response to obsrvations

Question 5

what is top down flow

Answer 5

feedback layers 2, 5, 6 –> lower layers

1, 5, 6 is predicted or habitual response

Question 6

how many layers in neocortex

Answer 6

6 layers

Question 7

describe structure of cerebral cortex

Answer 7

general uniformity of architecture with varying input and output

same cortical function everywhere varies only by input and output

ex = if destroy inf collicus, LGN wires into auditory cortex and reorganize inf colliculus for vision

Question 8

what are outbox, interoffice mail, and inbox for cortex

Answer 8

outbox = 5-6
interoffice mail = 1-3

inbox = 4a, b, c

Question 9

___ neurons in cortex are GABAergic inhib interneruons

Answer 9

20%

Question 10

EEG represents

Answer 10

summation through layers as measured at surface

Question 11

describe directions of flows of info

Answer 11

local + distant horiz and vertical flows of info

interoffice interoffice horiz

Question 12

describe basic classification of EEG rhythms

EEG measure

Answer 12

EEG measure bulk electrical potential from scalp surface

diff freq and patterns relate to diff states of being

Question 13

what does higher freq EEG mean

what does waves of activity mean

Answer 13

higher freq = more active
lower freq = less active

suggests neurons in area are doing roughly same thing

Question 14

what rhythms when not doing much

what rhythms in alert REM sleep

rhythm 
below 3.5
4-7.5
8-13
14-30
30-100

Answer 14

1) alpha
2) beta

3)
4)
5)
6)
7) gamma

Question 15

how does rhythmically bursting and randomly discharging families of brainstem and thalamic neurons appear to select and stabilize specific EEG patterns for arousal and attention

Answer 15

thalamic reticular nucleus’ control over thalamocortical info flow = conductor entraining diverse cortical members into concerted rhythm

rhythmic burst in thalamus during slow wave sleep, deep anesth, absence seizure (temporary detachment of thalamic relay from sensory input)

Question 16

how does rhythmically bursting and randomly discharging families of brainstem and thalamic neurons appear to select and stabilize specific EEG patterns for arousal and attention

how does cholinergic input impact system

Answer 16

1) ACh depol thalamic relay neurons
ACh inhib thalamic reticular nucleus

2) promote steady train of thalamic relay activity
3) opens thalamocortical gate to sensory info for attention and arousal