Neuro - EEG, SLEEP AND CIRCADIAN RHYTHMS Flashcards
where in the brain does the activity of sleep start? where does this area send projections to?
in the reticular formation of the brain stem, it sends projections to the thalamus and higher cortical areas
what neurotransmitter is closely linked with sleep?
serotonin
is it the suprachiasmatic nuclei or the hypothalamus that is also involved in making sleep happen?
both
the hypothalamus releases an excitatory neurotransmitter required for wakefulness. What is it called?
orexin (aka hypocretin)
when is orexin released?
during the waking state
an EEG is characterised by which type of waves when in a relaxed and awake state?
alpha waves, high frequency and high amplitude waves
an EEG is characterised by which type of waves when in an alert state?
beta waves , even higher frequency and low amplitude asynchronous waves
what characterises theta waves?
low frequency, can vary enormously in amplitude, common in children or in adults who are under emotional stress and frustration, or in sleep in both adults and children
what characterises delta waves?
very low frequency but high amplitude, they occur in deep sleep
in which stage of sleep does the EEG show bursts of rapid waves called “sleep spindles”?
stage 2
which stage contains exclusively delta waves?
stage 4
which are the stages known as deep sleep?
stages 3 and 4
in which stage does dreaming occur?
REM sleep
which are the stages known as slow wave sleep?
stages 1 to 4
which stage of sleep is known as paradoxical sleep? why?
REM sleep, because the EEG has desynchronised waves with high frequency and low amplitude, like the awake state
what are the physiological characteristics of deep wave sleep?
decreased vascular tone (low BP) and decreased basal metabolic rate (low BT) (BT=body temperature)
what are the physiological characteristics of REM sleep?
HR/RR irregular and brain metabolism increases
how does the brain prevent itself from acting out on dreams?
inhibitory projections from pons to spinal cord
what is the characteristic of REM sleep behavioural disorder?
people lack the inhibitory projections from pons to spinal cord and might act out their dreams
what two medication can be used to treat insomnia? what are the issues which each of these?
barbiturates (decrease in REM sleep and thin therapeutic index) and benzodiazepines (addictive)
what is narcolepsy? what is it caused by?
brain switches to REM sleep without warning. Caused by dysfunction orexin release by hypothalamus
where are the “master clock” neurones situated? (the ones which have an inherent 24 hours cycle)
suprachiasmic nucleus (SCM) of the hypothalamus
how are the “master clock” neurones entrained?
the light/dark cycle (although there are other cues as blind people
what stimulates wakefulness?
when orexin levels rise
what stimulates sleep?
when orexin levels plummet
does somnambulism occur in REM sleep? when does it occur?
it occurs exclusively in non-REM sleep, mainly in stage 4
