NN sleep lecture

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By: ABDULLAALZOBE (14 month(s) ago)

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SLEEP: 

SLEEP Nicoletta Nicolaou February 2005 CY/2/D2 – Intro to Neuroscience (picture from: http://www.stanfordalumni.org/news/magazine/1999/julaug/articles/sleep.html)

Sleep - Overview: 

Sleep - Overview What is sleep Falling asleep Sleep types, stages and cycle Why do we sleep? Sleep disorders Dreams Lucid dreams (picture from: www.hbkg.de/images/ sleep.jpg)

Sleep fundamentals: 

Sleep fundamentals “Sleep is a readily reversible state of reduced responsiveness to and interaction with the environment” [Bear et al] Fundamental behavioural states: - awake - non-REM sleep - REM sleep (picture from: http://www.cosmographica.com)

Getting to sleep: 

Getting to sleep Decrease in body temperature Built-up of prostaglandines Increased adenosine levels Increased GABA release (picture from: http://www.sfcall.com/images)

Non-REM sleep: 

Non-REM sleep Reduced muscle tension throughout body Minimal movement – body capable of movement, but brain rarely commands to Low temperature & energy consumption Heart rate, respiration & kidney function slow down Increased digestive process

Slide6: 

Brain is resting – energy use & general neuron firing rates at lowest point of day Cortex neurons oscillating at high synch; sensory I/p cannot reach cortex Detailed, entertaining dreams rare “An idling brain in a movable body”, W. Dement

Non-REM sleep stages: 

Non-REM sleep stages Stage 1 – transitional sleep; lightest stage. - EEG α rhythms less regular - eyes make slow rolling movements - duration few minutes Stage 2 – slightly deeper - occasional sleep spindle - K-complex observed - eye movements almost stop - duration 5-15 minutes

Slide8: 

Stage 3 - large amplitude slow δ rhythms - no eye or body movements Stage 4 – deepest stage - large 2Hz and slower rhythms - duration 20-40 minutes

REM sleep: 

REM sleep Dreaming period EEG almost indistinguishable from that of an active brain i.e. fast, low voltage fluctuations High oxygen consumption Increased and irregular heart & respiration rates

Slide10: 

Muscle atonia - exception: muscles controlling eye movements & tiny muscles in inner ear - respiratory muscles barely operate - eyes occasionally dart rapidly back & forth Body temperature drops Sexual arousal “An active, hallucinating brain in a paralysed body”, W. Dement

EEG, EOG and EMG during different sleep stages: 

EEG, EOG and EMG during different sleep stages (picture from ThinkQuest, http://www.thinkquest.org)

Sleep cycle: 

Sleep cycle (picture from: http://dreamtalk.hypermart.net/teachers/Scycles.htm)

Why do we sleep?: 

Why do we sleep? (1) Restoration: sleep to rest, recover and prepare to be awake But no physiological process restored or essential substance made or harmful toxin destroyed during sleep has been identified so far How does sleep repair us?

Slide14: 

(2) Adaptation: we sleep to - keep ourselves out of trouble - hide from predators when we are most vulnerable - conserve energy Example – squirrel Saving energy as body does just enough to stay alive during sleep

Sleep disorders: 

Sleep disorders Dyssomnias: - Restless Legs Syndrome - Periodic limb movements - Sleep-related eating disorder - Insomnia & Hypersomnia - Sleep apnea Parasomnias: - REM behaviour disorder - Sleep terrors - Sleepwalking (somnambulism) - Rhythmic movement disorder

Narcolepsy: 

Narcolepsy Unwanted sleep attacks. Symptoms: - excessive daytime sleepiness - cataplexy (sudden muscular paralysis while conscious) - sleep paralysis (similar loss of muscle control during transition between sleeping & waking) - hypnagogic hallucinations - automatic behaviour Genetic component No known cure, only symptom relief

Dreams: 

Dreams “Dreaming permits each & everyone of us to be quietly and safely insane every night of our lives”, W. Dement. Ancient cultures – dreams were window to higher world, source of info & guidance, power or enlightenment, alternative realities, prophetic visions, sexual fantasies (picture from: http://aussieangelgoff.tripod.com)

Slide18: 

Sigmund Freud – dreams were disguised wish-fulfilment; unconscious way of expressing our sexual & aggressive fantasies which are forbidden while we are awake (picture from: http://www.xasa.com)

Slide19: 

Allan Hobson & McCarley: “activation – synthesis”. Reject Freudian psychological interpretation. Dreams are associations & memories of the cerebral cortex elicited by random discharges of the pons during REM Alternative view – dreams originate partly from external stimuli, but mostly from brain’s own motivations, memories & arousal

Slide20: 

Suggestions that REM (& perhaps dreams) have important role in memory. REM somehow aids integration or consolidation of memories REM deprivation can impair ability to learn a variety of tasks No scientific evidence for sleep-learning Means by which brain gets rid of unnecessary or wrong info obtained while awake – reverse learning

Lucid Dreaming: 

Lucid Dreaming Dreaming while knowing that are you dreaming Usually begins in midst of dream when dreamer realises that it is a dream. Triggered by noticing some impossible or unlikely occurrence High-level & low-level lucidity (picture from: www.philadelphiaweekly.com)

Why have lucid dreams?: 

Why have lucid dreams? Adventure & fantasy Overcoming nightmares Rehearsal Creativity & problem solving Healing Trancedence Everybody can learn to have lucid dreams!

Thank you. . . : 

Thank you. . . (picture from: http://www.aquatt.ie/gallery/albums/sleep/1_G.jpg)