30 - Sleep + Consciousness Flashcards
What is consciousness
The ability to react appropriately
What is an EEG
Very small voltages recorded from the scalp
Used to record average activity of many thousands of nerve cells
What is the best use of EEGs
used to detect seizure activity or sleep/coma
What does a desynchronised appearance show in an EEG
When individual neurons are firing out of phase with each other
What part of the brain mediates consciousness
Cerebral cortex
What processes occur in normal (slow wave sleep/non rem sleep_
gh release
long bone growth
wound repair
cortisol decreases
When is melatonin released and where from
Released in sleep
from the pineal gland
Function of melatonin
free radical scavenger
maintains GABA function
prevents seizures in the brai
How many stages of sleep are there
4 normal stages 1 paradoxical (REM ) stage
What does slow wave activity indicate
Synchronisation of cortical activity
What does more synchronisation of cortical activity mean
Less conscious individual
Where is the control centre for sleep and wakefulness
Reticular formation of Pons
Function of neurones in pons
Keep us awake and alert
When are the neurones in the pons switched off
During sleep
What modulates the pontine centres
hypothalamus
Where is the BBB leaky
around the medial and ventrolateral preoptic nuclei in the hypothalamus
What is the effect of Ghrelin on sleep
Inhibitory action
What is the effect of CCK on sleep
Increases sleepiness
What is the effect of adenosine on sleep
Increase sleepiness
Action of caffine
Antagonist at A1 adenosine receptors
When are histaminergic neurons active
Active during waking
Silent during sleep
How does the preoptic nuclei regulate sleep
Modulating activity of TMN histaminergic neurones
What is the input to the suprachiasmatic nucleus
Retina
What is the function of the SCN
Regulation of the diurnal rhythm of sleep
Where does the SCN project to
tuberomamillary nucleus
What do lesions in the SCN cause
destruction of diurnal sleep rhythms
still sleep - but irregular patterns
Function of Orexins (hypocretins)
Maintain wakefulness
Cause of narcolepsy
Loss of orexin containing neurones by autoimmune attack from T-lymphocytes
Where are orexin cell bodies found
Posterior hypothalamus
What do orexins do
They project to various nuclei in the brainstem to stimulate release of acetylcholine, noradrenaline, serotonin, and dopamine. –> promote wakefulness
2 hypothalamic systems that control wakefulness
Histamine neurones of the tuberomamillary nucleus
Orexin neurones of the posterior thalamus
What causes sleep onset
Signals from pre-optic nuclei and SCN inhibit histamine and orexin neurones
Stops excitatory drive to the monoamine neurones of the pontine reticular formation
Where are dopaminergic cells found
Ventral tegmental area
Where are cholinergic cells found
Pedunculopontine n - project to thalamus
Nucleus basalis- sends cholinergic axons to all parts of the cerebral cortex
Where are noradrenergic cells found
Locus coeruleus
Where are serotonin cells
Raphe nuclei
Activity of Ach during sleep
INCREASES in REM sleep
Function of Ach
Enables thalamic and cortical programs to operate
Activity of NA in sleep
Drops LOW
Central NA - Alertness and attention
Activity of serotonin in sleep
Activity of 5HT STOP
What can SSRIs do to sleep
Decrease in sleep efficacy as increased 5HT
Activity of Dopamine in sleep
Low level
Allows for smooth movement in nigrostriatum
Allows for alertness and focus - mesolimbic and mesocortical
What drugs prevent sleep + why
Amphetamine
Cocaine
continuously release dopamine and NA
Function of REM sleep
Memory consolidation
removal of junk
coping with life’s stresses
Affect of TCAs on sleep
Promote sleep
Block H1 and NA reuptake
Affect of MAOIs on sleep
Decrease sleep
Increase dopamine, NA, 5HT
Insomnia treatment
Antihistamines - Nytol
Benzodiazapines - Diazepam
Zopiclone - Z drugs
Sleep apnea
Motor disconnection during REM does not avoid resp system
Stop breathing when start dreaming
Muscles of throat relax
Cause of SIDS
