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Lecture 9

Lecture 9 - Sleep & Arousal

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University of Toronto St. George
Human Biology
John Yeomans

HMB200H1S L9 Feb 07 2012Sleep and ArousalDiffuse Arousal Systems Suprachiasmatic nucleusendogenous oscillatorMany monoamine transmittersNorepinephrine neurons in locus coeruleus A6Dorsal tegmentum of ponsMesopontine Cholinergic neurons Ch56REM sleepRaphe Serotonin neurons B56Midbrain dorsalmedian rapheHistamine neurons in posterior hypothalamusSmall surfacerecording electrodeswaves go thru OrexinHypocretin neurons in lateral hypothlamusscalpAlso widely in brainstrap on chin hold caps to head to hold electrodes Orexin in narcolepsy cataplexystableBasal Forebrain Cholinergic neurons Ch14Any movements in head ex head strong jaw Thru hypothal expression can disruptcontaminate EEGAll Active in Waking Arousal200V not mV small hard to record found in 1930sNorepinephrine and SerotoninEEG and SleepWaking Alpha 914 1012 Hz relaxedbeta waves 1540 Hz gamma 40HzGammalow amplitude higher freqWhen thinking conceptuallybeta gammaAlphahigher amplitude smooth steadier almost SlowWave Sleep Slip from alpha to spindles 14 Hz approach sine waves more regular than any otherdelta 14 HzpotTheta58Hzby hippocampushippocampal Consistent w steady psychological feeling during input structure deep brain less important to meditation or calmnesssurface potsStages of slowwave sleepstill see alpha wavesNothing close to act pot 1000HzHigher freq interruptions spindles in middle in REM Sleep Cortical arousalmuscular atoniastage 2Also called paradoxical or dream sleepStage 3 a few sleep spindles more delta waves Eyes active cortex active muscles inhibited more prominent in stage 4 sleepFourier analysistell how much energy in each of Gradually from alpha to delta as go into these rangesunconscious sleep muscles still moving a bit but Triggered in pontine reticular formation by AChconscious brain activity decreasingother signals As go deeperlarger more irregular wavesEpileptic Seizures Synchronous cortex activityDuring first 6090minsCan be from brain damage chemical changes REMdream episodesgenetics too much glutamate not enough GABA Started in 2hrs in one subject 70mins in the inhibitionother intense pathological overactivation of cortexDont always start at same time dif durations petit mal seizure temporary loss of Then recurrence of slow waves REM consciousnessevery 90mins so sleep cycle said to be 90minsTemporal lobe activationNot circadian 24hrsOrgrand mal tonic clonic seizuresTend to get longer as night progresses General motor cortex activation10min30minVariable depending on length of sleep how tired mental activity on avg go from 510min2030min
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