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PSY290- Sleep and Circadian Rhythms lecture .doc

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John Yeomans

PSY290 SLEEP AND AROUSAL - what we know about transmitters →influence on waking arousal/rousing effect of brain stem activation - slow wave sleep and REM sleep, which does what (neurotransmitters) - narcolepsy and cataplexy Diffuse Arousal Systems: - norepinephrine and epinephrine in cxn to sleep - also widespread arousal of mesopontine cholinergic neurons, raphe serotonin neurons, histamine, etc. - found in dorsal pontine regions - locus coeruleus→one of diffuse activating systems →to hippocampus, basal ganglia, cortex Midbrain serotonin neurons→mesencephalic serotonergic cells project—thalamus, hypothalamus, basal ganglia, cortex - serotonin mediated analgesia (raphe nuclei?) Cholinergic Arousal Systems (*miportant for widespread arousal) - mesopontine cholinergic neurons near locus coeruleus also provide diffuse cholinergic arousal - activate dopamine nerons, all thalamic neurons →in turn activates cortex through synapse - also basal forebrain cholinergic neurons →activates entire cortex - basal forebrain + mesopontine cholinergic neurons =>widespread arousal 3 in forebrain importaint inslleep: Model of REM Sleep systems: - cortex activation—orexin-hypocretin, histamine, basal forebrain neurons =>all activate diffuse arousal systems - list going from caudal to rostral —Diffuse Arousal Systems list of neurons - histamine neurons in front of brain, orexin/hypocretin neurons in front of them, then basal forebrain in front of them (lost in degenerative disease) EEG and Sleep: - WAKING: Alpha + Beta/Gamma waves - looks like: - during waking states, either very relaxed with steadily quiet beating brain/intensely active brain with intense waves - strongest alpha waves = occipital lobes - multichannel EEG recordings displayed - these slow brain waves don’t represent action potentials - gamma=35+ Hz - higher Hz=lower amplitude, higher frequency - more dramatic ∆es when sleep - as you fall asleep, switch to gamma waves to slower waves (stage 1 to stage 4) - waves become larger and more irregular - peaks are highly irregular with peaks b/w 1-4 sec → ∆ waves - seen 40-60 minutes after falling asleep - waves progressive from pure alpha to delta, which is a gradual change - 60-90 minutes after falling asleep—dramatic changes in brain and therefore waves - quick transition into REM sleep; dream state; waking-like brain waves - from slow and large amplitude to high frequency and low amplitude - brain and eyes are very active, but muscles of body are profoundly more inhibited than any other time—no tension or electrical activity in muscles (limp body—atonia) - waking during REM —can recall dreams - brain more active, muscles inactive - NE and 5HT neurons silent & many cholinergic neurons activated - in slow wave sleep, brain and eyes are quiet, muscles are active Brain Areas—Early Studies: - discovered that coma results mainly from injury to dorsal pontine region (dorsal reticular formation) - leads to inability to wake up at all - by contrast, if you electically stimulate dorsal pontine region or similar region => widespread arousal - regions of lesion are usually in dorsal pons and midbrain in front of it - after shown that activating regulcular formationactivates from sleep, disovered 2 pathways—ascending reticular pathway + descending from pons to motor neurons for muscle arousal (when lesions occur, muscle atonia occurs) Sleep Disorders: - discovered sleep relation to happiness —one of first symptoms of depression=poor sleep habits - too little, poor waking habits - some are too much REM, some too little (insomnia) - Sleep Apnea=wake up right at onset of REM - during atonia, diaphragm not enough strength and cannot breathe (apnea) - especially occurs in middle-aged to older people w/high body mass - weight on diaphragm that cannot be overcome→not enough REM, depression follows - heavily associated with heart disease + obesity - Sleep Paralysis = REM persists after wake up - wake up and muscles still in atonic stage - occasionally happens to all of us, but not often - if persists, need help - Narcolepsy/cataplexy = daytime sleepiness and REM-atonia attacks - tiredness during day, use caffeine to keep going - as progresses, daytime sleepiness evolves into losing muscle strength in legs (fall over in heap) - in humans, best trigger is a stimulatingly funny/happy atmosphere (parties) →pleasurable arousal triggers atonia Epilepsy vs. Cataplexy: - epilepsy = uncontrolled excitation; brain firing intensely leading to seizure - if seuzure
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