37-Sleep Flashcards
defining criteria of sleep (x4)
- reduced motor activity
- reduced response to stimulation
- stereotypic postures (lying down in humans)
- relatively easy reversibility (as opposed to coma)
possible purposes of sleep (x4)
- glycogen replacement
- restorative (heart rate, respiration, body temp, O2 use)
- neural development
- learning? (possibly confounded by effects of stress on learning)
inherent circadian rhythm period in humans
about 25 hours
Stages of sleep primarily determined with ___
EEG
SWS
slow wave sleep
In SWS, ___ waves are dominant in EEG
delta (high amplitude, 0.5-4 Hz)
First few hours of sleep dominated by ___
slow wave sleep
Later few hours of sleep show increased ___
REM sleep
Fast EEG is [more/less] in REM over SWS
more
Muscle activity is [more/less] in REM over SWS
more
Dreaming is [more/less] in REM over SWS
more
Eye movements are [more/less] in REM over SWS
more
Brain metabolism is [more/less] in REM over SWS
more
Delta (and other sleep) waves result from changes in ___
activity of thalamocortical neurons
Thalamic neurons are [depolarized/hyperpolarized] during wakefullness
depolarized, for sensory transmission
Thalamic neurons are [depolarized/hyperpolarized] during sleep
hyperpolarized, to filter input
Mechanism of slow oscillations seen in SWS
- most thalamic neurons hyperpolarized so that external stimuli do not reach cortex
- hyperpolarization triggers depolarizing currents
- activation of I_h Na+ channels and action potentials in thalamic neurons
- synchronous PSPs and action potentials in cortical neurons
- GABA neurons in reticular nucleus of thalamus activation
- release of GABA causes re-hyperpolarization in thalamus, cycling
melatonin [incr./decr.] SWS duration by ___
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
REM-on neurons are located in ___
pontine reticular formation (aka pontine tegmentum?)
REM-on neurons release ___ onto ___ neurons, causing [hyperpolarization/depolarization]
Ach, thalamic, depolarization
Areas that change in activity during dreaming
- limbic system active (emotion)
- prefrontal cortex decreased (reduced inhibition of ‘social innapropriate though’?
- decreased working memory (forgeting dreams)
To reduce movement, REM-on neurons send [excitatory/inhibitory] projects to neurons in ___
excitatory, lower brainstem
Mechanism of reduced movement during sleep
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’
Lesioning ___ causes animals to appear to act out dreams
pontine reticular formation
catalepsy
sudden paralysis
REM-off neurons located in ___ and ___ (?)
raphe nuclei and locus ceruleus
Mechanism of exiting REM sleep
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
Arousal involves which systems (x4)
- midbrain reticular formation
- posterior hypothalamic neurons
- nucleus basalis
- locus ceruleus
Characteristics of narcolepsy (x5)
- sudden sleep attacks, often during emotion
- loss of muscle tone
- hallucinations
- abnormal sleep/wake cycles
- relation to hypocretin/orexin
Hypocretin neurons are [incr./decr.] in humans with narcolepsy
decr.
HCRT
hypocretin
Loss of HCRT neurons reduces activation of ___ and __, causing sleepiness
nucleus basalis of Meynert, locus ceruleus
Loss of HCRT neurons reduces activation of ___, causing disturbed circadian sleep rhythms
suprachiasmatic nucleus in hypothalamus
Is narcolepsy an autoimmune disease+
probably
