Sleep And Consciousness Flashcards
EEG
Voltage of different brain areas measured by scalp electrodes
What creates the electrical activity picked up by EEG
Summation of EPSPs and IPSPs from neurones near electrode
When are gamma waves present
Active information processing
When are beta waves present
Active wakefulness
REM sleep
When are alpha waves present
Relaxed wakefullness
Eyes closed
When are theta waves present
Sleep
Meditation
When are delta waves present
Deep slow wave sleep
Which type of wave is most affected by artefacts from muscle activity
Gamma
What creates a low amplitude desynchronised appearance on EEG
Neurones firing out of phase
What creates a high amplitude slow wave appearance o EEG
Neurones firing in phase
In a normal awake brain are neurones firing synchronously or asynchronously
Asynchronously
How does EEG frequency and amplitude vary between synchronous and asynchronous activity
Synchronous - high freq low amp
Asynchronous- low freq high amp
Consciousness
Ability of an individual to react appropriately to stimuli in the outside world
Coma
Unarousable unresponsiveness with or without reflexes
Unconsciousness
Arousable but often only temporarily by strong stimuli
Sleep
Arousable by normal stimuli
Drowsy wakefulness
Responding in a non reflex way
Normal wakefulness
Responding to spoken or written stimuli
High arousal
Hyper alert and fast reactivity
How is consciousness assessed
GCS
3 components of GCS and what they are scored out of
Eye opening 4
Verbal response 5
Motor response 6
EEG characteristics during a seizure
High amplitude synchronised firing
How does EEG frequency and amplitude change moving through the sleep cycle
Freq decr
Amp incr
Slow wave sleep function
Immune, nervous, skeletal, and muscular system growth and maintenance
Removal of waste products from Cells
Brain glycogen store incr
Memory consolidation
Where from and when is melatonin released
Pineal gland
Slow wave sleep
How does melatonin prevent oxidative damage
Free radical scavenger
REM functions
Dreaming
Memory consolidation
Remove unnecessary memories
Coping with stress
How do dreams prevent memory decay
Retrieving, reliving, and re-storing long term memories as dreams strengthen neural connections in the memory
What part of the brain are the key control centres of sleep and wakefulness in
Reticular formation in pons
What controls activity of pontine reticular neurones
Hypothalamus
Does the reticular formation cause wakefulness or sleep
Wakefulness
Stimuli for sleep
Adenosine
Leptin
Diurnal rhythm
Melatonin
Factors that reduce sleep
Caffeine
Ghrelin
Low blood glucose
Orexins
Tuberomamillary system
What receptor does caffeine antagonise
A1 Adenosine receptor
What increases intracellular adenosine formation
Incr Cellular workload
Incr o2 consumption
Excitatory transmitter release
What part of the thalamus regulates the diurnal rhythm
Suprachiasmic nucleus
Melatonin roles
Synchronising circadian rhythm
Sleep wake timing
Blood pressure regulation
Seasonal rhythms
How does melatonin exert effects
Activate melatonin receptors
Antioxidant
circadian clock master genes
BMAL
CLOCK
Circadian clock target genes
Period genes - PER1 PER2 PER3
Cytochrome genes - CRY1 CRY2
Where are orexin cell bodies and where do they project to
Cell bodies in lateral hypothalamus
Project to all areas of cortex
What causes narcolepsy
Autoimmune attack on orexin neurones
What NT do tuberomamillary system neurones release
Histamine
Is the tuberomamillary system tonically active in sleep or wakefulness
Wakefulness
When does sleep onset occur
When signals from sleep promoting hypothalamic nuclei inhibit wakefulness promoting neurones
Sleep promoting hypothalamic nuclei
Venterolateral Preoptic nuclei
Suprachiasmic nucleus
Wakefulness promoting neurones
Tuberomamillary nucleus
Lateral hypothalamus
What do wakefulness promoting neurones stimulate
Cerebral cortex and pontine reticular formation
3 families of monoamine neurones in reticular formation
Cholinergic
Noradrenergic
Serotoninergic
Activity of reticular formation noradrenaline, serotonin, and cholinergic neurones during wakefulness
Noradrenaline - spontaneously active
Serotonin - active at steady level
Cholinergic - spontaneously active
Activity of reticular formation noradrenaline, serotonin, and cholinergic neurones during SWS
Noradrenaline- low
Serotonin - low
Cholinergic - low
Activity of reticular formation noradrenaline, serotonin, and cholinergic neurones during REM
Noradrenaline - low
Serotonin - none
Cholinergic - spontaneously active
When are reticular formation noradrenaline neurones most active
Fight or flight
What causes dreams
Cortex activated by cholinergic input but has no sensory information due to lack of serotonin activity so generates images and perceptions from memories
Which voluntary muscles are not paralysed in REM
Muscles involved in breathing and eye movement
What prevents people acting out their dreams
REM sleep Atonia
REM sleep Atonia
Paralysis of all voluntary muscles except diaphragm and extraocular muscles
What causes sleep apnea
REM sleep Atonia affects respiratory muscles
What causes ppl to wake up during sleep apnea
Anoxia triggers sympathetic nervous system to release adrenaline
How can sleep apnea lead to stroke
Sympathetic activity surge causes BP surge which can rupture brain blood vessels
Sleep apnea effects
Disturbed sleep
Chronic fatigue
Depression
Stroke
REM sleep Antonia mechanism
Glutaminergic subcoeruleus nucleis excites GABA and glycine inhibit neurones switching off motor neurone activity
