Week 10 Pt 2: Sleep And Waking Flashcards
What are circadian rhythms?
Physical, mental and behavioural changes that follow a roughly 25-hour cycle
Responds primarily to light and darkness in an organisms environment
What is ultradian?
Shorter cycles
e.g. pulsatile release of pituitary hormones, apetite
What is infradian?
Longer
e.g. ovarian cycle
What does suprachiasmatic nucleus within hypothalamus have?
Input from retina via Ganglia cells which are responsive to light
What do retinal rod and cones project onto?
Ganglia cells which form axons of optic nerve
What does optic nerve axons have?
Light sensitive neurons (respond to blue light)
What is suprachiasmatic nucleus?
master pacemaker
What cells from outside the SCN exhibit circadian pattern?
Pituitary gland
Pineal gland
Outside brain: liver, lungs
What is SCN?
Paired nuclei found within the hypothalamus
What is the function of SCN?
Maintain circadian rhythms or biological pattern that follow 24 hour cycle
What do cells of SCN contain?
Biological clock
What does cells in SCN produce?
2 proteins:
Clock
BMAL1
What does clock/BMAL1 promote the transcription of?
PER and CRY genes
What happens when PER and CRY genes bind together?
Inhibit the transcription of their own genes
SCN
PER and CRY proteins begin to degrade
Allow clock/BMAL1 to promote PER and CRY transcription again
Entire cycle takes about 24 hours
What is found in the core region of SCN?
Vasoactive intestinal peptide
What is found in the shell region of SCN?
Vasopressin
Where does input coming from light go to?
Core region of the SCN
What is the major input of SCN?
Light entrainment directed from ganglion cells (sensitive to light)
Inputs from serotonergic systems
Input from processing if intergeniculate nucleus
What is the intergeniculate nucleus?
Nucleus associated in reflex behaviours of visual system
Where does the shell region of SCN transmit the information to?
Brain
Where does the ventral subparaventricular zone project to?
Dorsal medial nucleus of the hypothalamus
What is dorsal medial nucleus involved in?
Circadian regulation
Particular temperature regulation
Through medial preoptic area
What does output to dorsal-paraventriculsr nucleus of hypothalamus involve?
Sympathetic regulation of melatonin production
What is sleep cycle driven by?
Inhibitory group of neurons in ventrolateral preoptic area
What is melatonin production caused by,
Sympathetic nerve activity to the membrane pineal gland found above the midbrain
How is melatonin secreted?
A short light burst
What does melatonin supplement?
Suprachiasmatic neural output and reinforces them
What does melatonin have an effect on?
Normal sleep pattern
What is important for sleep?
Preoptic area
What is necessary for survival deprivation?
Animal models Loss of weight Failure to regulate body temperature Infections Death
Human studies
Cognitive and memory impairment Leads to mood swings Hallucinations Fatal familial insomnia condition REM sleep ( rapid eye movement sleep)
What is stage 1/2 of sleep as seen on EEG?
Sleep spindle is seen
Organised activity/ bursting activity/wider and higher amplitude - lower frequency EEG patterns
Stage 3/4 of sleep seen on EEG
Slow waves/delta waves
High amplitude
Slow wave EEG pattern
When does rapid eye movement state of sleep Increase?
during night
Slow wave sleep
Considered stages III and IV
What are active during REM sleep?
EOG-electro-oculogram- muscles
What is observed during REM sleep?
Large muscles show paralysis
What dominates in slow wave sleep?
Parasympathetic activity
What neurotransmitter is involved in sleep/waking cycle?
Serotonin
Noradrenaline
Where are the ACH cells found?
Between junction of mesencephalon and pons
What prompted the cortical arousal?
Reticular formation has key nuclei
What are important for waking stage?
Brainstem
Locus coeruleus and Raphe
ACH projections
What brain regions are important for sleep promoting?
Anterior hypothalamus
Ventrolateral posterior
Ventrolateral preoptic area
What plays an important role in controlling the sleep wake transition?
Oregon neurons of the lateral hypothalamus
What does Previn neurons promote?
Arousal and wakefulness
What does autoimmune destruction of ore in neuron cause?
Narcolepsy
What does circadian rhythm do?
Keep us awake
What is caffeine?
Antagonist against adenosine receptor
What did Borberly and Dawn ‘84 purpose?
Circadian process and sleep homeostasis are integrated
What does sleep homeostatic process Increase with?
Length of time awake
What are the two electrophysiological state of Thalamocortical neurons?
Bursting
Totally active
