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38 Cards in this Set
- Front
- Back
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What is sleep?
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Transient dynamic state.
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What is sleep function?
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It is fundamental for human health and performance.
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What is sleep measured on in a laboratory?
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A polysomnographic perspective.
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What is active in stage 1 sleep?
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Fast brain activity
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What is active in stage 2 sleep?
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Brain starts to slow down.
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What is active in stage 3 sleep?
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Brain is slowed right down.
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What does a cycle of sleep look like?
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Stage 1, stage 2, stage 3, stage 4, REM, back to the start.
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What is homeostatic sleep?
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Sleep homeostasis denotes a basic principle of sleep regulation. A sleep deficit elicits a compensatory increase in the intensity and duration of sleep, while excessive sleep reduces sleep propensity. Slow waves in the electroencephalogram (EEG), a correlate of sleep intensity, serve as an indicator of sleep homeostasis in nonREM sleep, also referred to as slow-wave sleep in animals.
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What is slow wave sleep?
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Slow-wave sleep (SWS), often referred to as deep sleep, consists of stage 3 and 4 of non-rapid eye movement sleep.
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What is the difference between homeostatic sleep and circadian clock regulation?
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The homeostatic mechanism regulates sleep intensity, while the circadian clock regulates the timing of sleep.
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What did Bremer proposed in 1937?
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That EEG activation depended on sensory input.
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What did Von Economo propose for the first time in 1930?
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That the hypothalamus is key to the process of arousal.
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What is the thalamocorical loop?
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Midbrain - cortex, thalamocortical loop, thalamus.
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How do thalamic neurons fire in response to steady activation from MRF?
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regularly.
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How do thalamic neurons fire in response to decreased activation from MRF?
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Irregularly.
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How does the ascending activation system maintain an activated cortex?
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It runs from reticular formation to thalamus to cortex.
it arouses or awakens the brain The cortex projects back to thalamus forming thalamocortical loop. |
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What controls the ascending (reticular) activating system?
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Two main branches:
1) Cholinergic inputs - pedunculopontine & laterodorsal tegmental nuclei. 2) Monoaminergic inputs - numerous excitatory inputs to the cortex. |
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What is the Locus Coeruleus high in?
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Noreprinephrine - it is high during wake, less during NREM. Off in REM
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What is Raphe Nuclei high in?
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Serotonin - it is high during wake, less during NREM. Off in REM.
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What is Tuberomamillary high in?
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Histamine - active during wake. Blocking histamine receptors = sleep.
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What is the substantia nigra & ventral tegmental area high in?
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Dopamine - DA containing neurons change firing according to reward, movement & cognition.
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What was discovered in 1998?
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Essential role in stabilisation of wakefulness. The Hypocretins/orexin contains neurons have widespread projections throughout the CNS.
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What is the VLPO system?
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Inhibitory signals from VLPO overcomes wake-system to allow sleep
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What is the Monoaminergic neurons?
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Inhibitory signals from monoaminergic neurons overcomes sleep system to allow wake
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If VLPO is switched off what happens?
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Stimulation by orexin neurons overcomes inhibition from the sleep promoting system
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What happens if monoaminergic neurons is switched off?
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VLPO neurons inhibits BOTH orexinergic and monoaminergic neurons to suppress wake and allow sleep
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What is Adenosine?
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by product of energy metabolism. increases in awake brain, decreases in sleep
-analogs injected into preoptic area = enhance SWS -inhibits diffuse modulatory arousal systems (NE, 5HT and ACh) -Adenosine receptor antagonist = caffeine |
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Input in to the SCN occurs via what three pathways?
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1)Input from the eyes via the retino-hypothalamic tract (photic)
2)The geniculo-hypothalamic tract (non-photic & photic) 3)Raphe-hypothalamic tract (non-photic & photic) |
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What are non-photic zeitgebers?
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-ambient temperature,
-food availability -physical activity (exercise), -social contact/work |
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If you put light into an eye what happens?
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Melatonin level decreases.
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If you turn a light off and an eye goes into darkness what happens?
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Melatonin levels increases.
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How do researchers measure circadian rhythmicity?
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Distinguishing between endogenous timing and exogenous timing through constant routine.
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What is constant routine?
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keeps constant exogenous time cues to allow researchers to measure the endogenous clock timing system
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What is kept routine in the lab when measuring sleep?
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Ambient lighting
Sleep:wake Temperature Dietary intake Movement |
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Why use forced desynchrony (FD)?
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Uncoupling the circadian system from the homeostatic system.
Measuring circadian period. |
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What is the biology behind the FD?
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An enforced day length, beyond the range of entrainment, circadian rhythmicity will free-run with its intrinsic periodicity.
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What would a FD short 'day' length be?
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20 h day (6h40 min sleep/13h20min wake)
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What would a FD long 'day' length be?
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28 h day (9h20min sleep/ 18h40min wake)
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