37-Sleep

Question 1

defining criteria of sleep (x4)

Answer 1

• reduced motor activity
• reduced response to stimulation
• stereotypic postures (lying down in humans)
• relatively easy reversibility (as opposed to coma)

Question 2

possible purposes of sleep (x4)

Answer 2

• glycogen replacement
• restorative (heart rate, respiration, body temp, O2 use)
• neural development
• learning? (possibly confounded by effects of stress on learning)

Question 3

inherent circadian rhythm period in humans

Answer 3

about 25 hours

Question 4

Stages of sleep primarily determined with ___

Answer 4

EEG

Question 5

SWS

Answer 5

slow wave sleep

Question 6

In SWS, ___ waves are dominant in EEG

Answer 6

delta (high amplitude, 0.5-4 Hz)

Question 7

First few hours of sleep dominated by ___

Answer 7

slow wave sleep

Question 8

Later few hours of sleep show increased ___

Answer 8

REM sleep

Question 9

Fast EEG is [more/less] in REM over SWS

Answer 9

more

Question 10

Muscle activity is [more/less] in REM over SWS

Answer 10

more

Question 11

Dreaming is [more/less] in REM over SWS

Answer 11

more

Question 12

Eye movements are [more/less] in REM over SWS

Answer 12

more

Question 13

Brain metabolism is [more/less] in REM over SWS

Answer 13

more

Question 14

Delta (and other sleep) waves result from changes in ___

Answer 14

activity of thalamocortical neurons

Question 15

Thalamic neurons are [depolarized/hyperpolarized] during wakefullness

Answer 15

depolarized, for sensory transmission

Question 16

Thalamic neurons are [depolarized/hyperpolarized] during sleep

Answer 16

hyperpolarized, to filter input

Question 17

Mechanism of slow oscillations seen in SWS

Answer 17

1. most thalamic neurons hyperpolarized so that external stimuli do not reach cortex
2. hyperpolarization triggers depolarizing currents
3. activation of I_h Na+ channels and action potentials in thalamic neurons
4. synchronous PSPs and action potentials in cortical neurons
5. GABA neurons in reticular nucleus of thalamus activation
6. release of GABA causes re-hyperpolarization in thalamus, cycling

Question 18

melatonin [incr./decr.] SWS duration by ___

Answer 18

increases duration b/c reticular nucleus neurons express melatonin receptors, so melatonin induces bursts of firing that inhibits thalamus and prolongs SWS duration, and possibly helps trigger SWS

Question 19

REM-on neurons are located in ___

Answer 19

pontine reticular formation (aka pontine tegmentum?)

Question 20

REM-on neurons release ___ onto ___ neurons, causing [hyperpolarization/depolarization]

Answer 20

Ach, thalamic, depolarization

Question 21

Areas that change in activity during dreaming

Answer 21

• limbic system active (emotion)
• prefrontal cortex decreased (reduced inhibition of ‘social innapropriate though’?
• decreased working memory (forgeting dreams)

Question 22

To reduce movement, REM-on neurons send [excitatory/inhibitory] projects to neurons in ___

Answer 22

excitatory, lower brainstem

Question 23

Mechanism of reduced movement during sleep

Answer 23

REM-on pontinue reticular neurons send excitatory projects to neurons in lower brainstem
-> These project to motor neurons, where they release inhibitory GABA or glycine
-> This produces ‘active paralysis’

Question 24

Lesioning ___ causes animals to appear to act out dreams

Answer 24

pontine reticular formation

Question 25

catalepsy

Answer 25

sudden paralysis

Question 26

REM-off neurons located in ___ and ___ (?)

Answer 26

raphe nuclei and locus ceruleus

Question 27

Mechanism of exiting REM sleep

Answer 27

REM-off neurons project from raphe nucleus and locus ceruleus to REM-on neurons in pontine reticular formation -> 5-HT and NE inhibit REM-on cells -> REM is turned off

Question 28

Arousal involves which systems (x4)

Answer 28

- midbrain reticular formation - posterior hypothalamic neurons - nucleus basalis - locus ceruleus

Question 29

Characteristics of narcolepsy (x5)

Answer 29

- sudden sleep attacks, often during emotion - loss of muscle tone - hallucinations - abnormal sleep/wake cycles - relation to hypocretin/orexin

Question 30

Hypocretin neurons are [incr./decr.] in humans with narcolepsy

Answer 30

decr.

Question 31

HCRT

Answer 31

hypocretin

Question 32

Loss of HCRT neurons reduces activation of ___ and __, causing sleepiness

Answer 32

nucleus basalis of Meynert, locus ceruleus

Question 33

Loss of HCRT neurons reduces activation of ___, causing disturbed circadian sleep rhythms

Answer 33

suprachiasmatic nucleus in hypothalamus

Question 34

Is narcolepsy an autoimmune disease+

Answer 34

probably