Sleep

Question	Answer
EEG	Cells in brain fire in mass that discharges little charges that we can detect in scalp; neurons in grey matter are vertical and discharge a positive and negative charge
beta waves	day to day wakefulness; high frequency, low amp
alpha waves	relaxation state; slower, increase in amp
stage 1	hard to differentiate between this and relaxation but theta waves are present; somewhat conscious; hypnotism, lucid dreams
stage 2	theta waves still there but also sleep spindles (burst of oscillatory activity; inc in wave freq) and k complex (inc in wave amp; works to suppress cortical arousal and stimulates memory consolidation)
stage 3/4	delta waves (slowest and highest amp); very hard to arouse, groggy-headed when wake up in this stage
REM sleep	sawtooth waves, similar to beta waves; paradoxical sleep because brain seems to be functioning as if it is awake
who sleeps?	Almost all mammals show REM sleep and similar brain activity patterns Birds also show REM sleep, little more than few minutes each night Reptiles and amphibians don’t show REM sleep but do show some of the other stages Insects and fish show behavioral sleep (reduced motor activity, increased input of sensory info to respond, need to rest) Plants also show some sort of circadian cycles. Predators tend to sleep more; prey do not.
circadian rhythm	naturally occurring 24 hr cycle
thalamus activity during sleep	Thalamus is relay station and during phase, thalamus is very busy communicating with cortex; as we sleep, thalamus ramps down relay station, activity wanes; as sink deeper and deeper, thalamus shuts out some incoming information
pons activity during REM	During REM, pons keeps regular timing, Every 90 mins, pons sends signal to thalamus to change its activity and send different info to cortex - Changes activity in visual, motor, emotion/social areas - Thalamus gates down activity in prefrontal cortex - Pons prevents brain from sending motor signals down spinal chord
loss of REM-related atonia	researchers prevented pons from shutting off motor activity, cats do not experience REM-related atonia, cats begin to act out their dreams; rare cases in humans can happen in old men
narcolepsy	disorder in which sudden sleep attacks occur in middle of waking activities; really strong emotional reaction triggers sleep
myotonia congenita (fainting goat syndrome)	sudden onset of muscle rigidity/ paralysis after strong environmental stimulus
YH Case	Shrapnel injury to pons Reported never dreaming Never entered REM sleep No real cognitive consequences without REM sleep
Why sleep?	preservation and protection theory restoration theory memory consolidation and insight
preservation and protection theory	sleep emerged in evolution to preserve energy and protect during day when there is little value and considerable danger
restoration theory	body wears out during day, need time to repair (growth-producing hormone only emitted during sleep, restoration of brain and other organs, immune system doesn’t function as well without sleep)
memory consolidation and insight	sleep enhances procedural memory hippocampus is convergence zone
sleep deprivation experiments	-EEG systems connected to rat, rats sleep deprived Sleep-deprived rates didn’t fare too well: disheveled, clumped, yellowing fur despite continued grooming; rapid decrease of weight, despite increased consumption of food, hypothermia, lesions on feet and tail, no rat survived more than 3 weeks of total sleep deprivation
why dream?	two theories: Freud: dreams are guardians of sleep Hobson: activation-synthesis model
latent thought	what the unconscious is trying to convey
manifest content	what we are actually dreaming about; psychoanalysis used to uncover latent content
activation-synthesis model	dreams are produced when the mind attempts to make sense out of the random neuronal activity that occurs in brain during sleep
cardinal cognitive features of dreams	sensation highly intense emotional content (ventromedial PFC) loss of directed thought/self-reflection (deactivation of dlPFC) reduction in logical reasoning poor memory

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	Created by Sneha Mittal about 8 years ago