B.B. Exam IV Study Guide.docx - Biological Rhythms Sleep Circadian Rhythms Rhythms that last ~24 hr Endogenous have an internal cause or origin o Ex

B.B. Exam IV Study Guide.docx - Biological Rhythms Sleep...

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Biological Rhythms & SleepCircadian Rhythms Rhythms that last ~24 hrEndogenous: have an internal cause or originoEx: Body tempHormone levels (i.e. melatonin)Sensitivity to drugs Eating & drinkingDigestion & excretion Attention Sleep/wakeZeitgeber: “time-giver”; light is a time-giverEntrain: set by; circadian rhythm is entrained by lightFree-run: animal relies on his/her internal rhythm b/c external cues were removedRetinohypothalamic PathwayLight retina SCN Pineal gland makes melatonin; melatonin is inhibited by lightLess light = more melatoninClock GenesThese & their protein products are made & degraded in a 24 hr. period Activity of SCN neurons cycles every 24 hr Physiological & behavioral circadian rhythmsOnce genes & proteins are made, they turn themselves ofSCN lesion & transplantIn a normal hamster lesion SCNoBecomes arrhythmic (circadian rhythms go away)Then transplant fetal SCN tissue from a mutant hamster w/ 20 hr c.r.hamster develops a 20 hr rhythmStages of sleep As sleep progresses (stage 14) EEG voltage increases and frequency decreasesoDecrease in breathing & HR from 14Stages 3 & 4:oSlow wave sleep (SWS)
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oDelta waves indicate synchronous activity of neuronsParadoxical (or REM)oBrain activity is high (in some brain regions)oMuscle tone is lowoIncreased facial twitches & irregular breathingMost SWS in first half of sleepMost REM sleep in second half of nightSleep Changes with AgeAs humans age, we spend less time sleeping overall & less time in REM sleepCritters that are further developed than humans sleep lesssuggests that sleep is important for brain development (humans sleep a lot)Functions of Sleep & Brainwashingenergy conservation to isolate (sequester) self & avoid predation when behavior is inefficientmemory consolidation restoration (rebuild proteins, clear out debris*)o*adenosine: breakdown product of ATPBrainwashing: change in the brain’s extracellular space b/w sleep & waking states may drive the clearance of metabolites & toxinsWhat Makes Us Sleep?Circadian signalsoClock genes/proteinsoMelatoninHomeostatic mechanismsoAccumulation of sleep-promoting chemicals (adenosine)oSo, wakefulness leads to deviationfrom homeostasisNeural controloHypothalamus *pressures to sleep from above factors can be overridden by acute stressors like fear or hungerBrain Regions involved in SleepHypothalamusoPromotes sleep & inhibits wakefulness-promoting regionsNuclei in pons & midbrain coordinate REMoCortical activation
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oSpinal paralysisoRapid eye movementsWakefulness is promoted by forebrain & brainstemPatterns of Brain Activity During DreamsSomeof cortex is activeono activity in sensory cortexoPFC is inactive*think PFC functionsMemory is weak (for STM)Logic is lackingPoor judgmentAmygdala is active strong emotional content
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