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SLEEP

SLEEP. Lecture Preview. A Physiological and Behavioral Description of Sleep Disorders of Sleep. Electrophysiological Measures for Sleep. Electroencephalogram (EEG) – neural activity Electromyogram (EMG) – muscle tension Electro-oculogram (EOG) – eye movements. EEG.

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SLEEP

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  1. SLEEP

  2. Lecture Preview • A Physiological and Behavioral Description of Sleep • Disorders of Sleep

  3. Electrophysiological Measures for Sleep • Electroencephalogram (EEG) – neural activity • Electromyogram (EMG) – muscle tension • Electro-oculogram (EOG) – eye movements

  4. EEG • Large disk electrodes on the scalp record electrical potentials • Extracellular voltage changes over a relatively large area of cortex (~ cm) • Better temporal resolution vs. spatial

  5. Get your own EEG system http://emotiv.com/ http://www.ted.com/talks/tan_le_a_headset_that_reads_your_brainwaves.html

  6. Measuring Stages of Sleep • Major changes (different patterns) of EEG during course of night’s sleep Frequency: Hertz (Hz) = Cycles per Second

  7. Awake • Alpha activity – 8-12 Hz (resting) • Beta activity – 13-30 Hz (active, desynchrony) Beta Alpha

  8. Stage 1 Sleep • Theta activity – 3.5-7.5 Hz (more synchrony) • Transitioning from wake to sleep Theta

  9. Stage 2 Sleep • Theta activity • Sleep spindle – 12-14 Hz (occurs 2-5 times per minute) • K complexes – occurs once per minute, more exclusive to Stage 2 Sleep K Complex Sleep Spindle

  10. Stage 3/4 Sleep (Slow Wave Sleep -SWS) • Delta activity - < 3.5 Hz • Difference unclear • Delta activity more dominant in Stage 4 Stage 4 – Deepest stage of sleep

  11. EEG and Single-Cell Activity for SWS • Downstate – neurons are hyperpolarized and do not fire • Upstate – neurons are firing

  12. Rapid Eye Movements (REM) Sleep • 90 minutes from beginning of sleep, 45 minutes from onset of stage 4 • Desynchrony begins to occur (similar to Stage 1) • Different eye movement • Muscles relax (paralysis) Theta Beta

  13. Hypnogram – A Single Night’s Sleep

  14. Transition from Slow Wave to REM to Wake http://www.youtube.com/watch?v=uDX8EHNi6So

  15. Mental Activity During Sleep • Mental activity may occur during both REM and SWS • REM • Eye movements made during REM are related to the visual imagery that occurs while we dream • Particular brain mechanisms that become active would have been active if the events in the dream were actually occurring (e.g. cortical and subcortical motor mechanisms) • SWS (Non-REM) • Nightmares, feeling of “falling” – stage 4

  16. Mental Activity During Sleep (REM) • Visual Association Cortex • High blood flow • High level of activity • Prefrontal Cortex • Low blood flow • Low activity • Primary Visual Cortex • Low blood flow • Low activity

  17. Interpretation of dreams • Older models (Freud) • Dreams are triggered by unacceptable repressed wishes, often sexual • Manifest dreams – disguised versions of our real dreams (latent dreams) • Modern models • Re-enactment of what happened during day, consolidating important memories • Activation-synthesis theory- Information supplied to the cortex during REM sleep is largely random and that the resulting dream is the cortex’s effort to make sense of these random signals.

  18. Lucid Dreaming • Knowing that it is a dream while dreaming • Taking control of the dream Left hand clench Real Imagined Dreamed Martin Dresler, Stefan P. Koch, Renate Wehrle, Victor I. Spoormaker, Florian Holsboer, Axel Steiger, Philipp G. Sämann, Hellmuth Obrig, Michael Czisch. Dreamed Movement Elicits Activation in the Sensorimotor Cortex. Current Biology, Published online Oct. 27, 2011 DOI: 10.1016/j.cub.2011.09.029

  19. Lecture Preview • A Physiological and Behavioral Description of Sleep • Disorders of Sleep • Insomnia • Narcolepsy • REM sleep behaviour disorder • Problems associated with SWS

  20. Insomnia • 25% of population occasionally, 9% regularly • Inadequate amount and/or quality of sleep interfering with normal day time functioning • Difficulty falling asleep • Difficulty maintaining sleep • Early awakening

  21. Medical Causes of Insomnia • Sleep Apnea– fall asleep and cease to breathe • Lack of oxygen in blood stimulates chemoreceptors and person wakes up gasping for air, after sufficient oxygen cycle stars again • Obstructive – obstruction via muscle spasms/atonia • Central – failure of CNS to stimulate respiration • Periodic limb movement disorder (PLMD) • Periodic, involuntary movements of limbs such as leg twitches

  22. Treatments for Insomnia Sleep Apnea – breathing mask, surgery PLMD – dopaminergic drugs, anticonvulsants • Sleep restriction therapy – reduce time in bed to estimated total time actually sleep in an average night, increase time spent in bed gradually • Stimulus control therapy – go to bed when sleepy, avoid reading, TV, snack, etc.

  23. Severe daytime sleepiness Narcoleptic sleep attacks Boring conditions Hypnogogic hallucinations Dream while awake, paralyzed Sleep Paralysis Just be before sleep or waking Cataplexy - sudden loss of muscle tone Emotional conditions Hypersomnia - Narcolepsy Narcolepsy

  24. Living with Narcolepsy and Cataplexy BBC News http://www.youtube.com/watch?v=vM4e1dQiqQw

  25. Narcolepsy Rust the Narcoleptic Dog • 1:2000 • Involves gene on chromosome 6, strongly influenced by unknown environmental factors • Mutation of specific gene responsible for canine narcolepsy • Involves orexin B receptor

  26. Orexin neurons • Narcolepsy (with cataplexy) caused by loss of orexinergic neurons in most cases • Humans – complete absence of orexin in 7 out of 9 narcoleptic patients Most patients are born with orexin, but during adolescence the immune system attacks these neurons, symptoms begin

  27. Treatment of Narcolepsy • Stimulants • Methylphenidate (ritalin) – catecholamine agonist for sleep attacks • Antidepressants – facilitate 5-HT and NA activity • Treats REM phenomena (cataplexy, sleep paralysis, hypnagogic hallucinations) • Modafil (newly available stimulant) – stimulant • Acts on orexinergic neurons • Increased Fos protein in orexin neurons

  28. REM Sleep Behaviour Disorder • Act out dreams, behaviour is opposite of cataplexy • Neurogdegenerative disorder with some genetic component, but could be caused by brain damage • Caused by lack of inhibition of motor neurons that normally occurs during REM sleep • Treatment – clonazepam (benzodiazepine)

  29. SWS Sleep Disorders • Problems Associated with Slow-Wave Sleep • Nocturnal Enuresis – bedwetting. • Somnambulism – sleepwalking. • Pavor Nocturnus – night terrors. • Sleep-Related Eating Disorder – eating during sleepwalking, often without recollection.

  30. Supposedly for a good night’s sleep...

  31. Feedback for me  • One thing you liked about the lecture • One thing you feel could be improved • One thing that would make lectures better for your learning purposes

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