SDRB- sleep and circadian rhythms

what do we measure sleep though?

polysomnogram

what is a polysomnogram?

combination of lots of different sleep records

what does an EEG measure

neural signals in the brain

what does a EOG (electro-oculogram) measure?

eye movement

What does an EMG (electro-myogram) measure?

muscle activity

what does an ECG (electrocardiogram) measure?

heart rate

what other 2 measurements are taken in a polysomnogram, excluding EEG, EOG, EMG and ECG?

Airflow and Oximeter

what is 1 hertz?

1 cycle per second

what is the Hz range for Beta waves?

13-30 Hz

what is the Hz range for Alpha waves?

8-13 Hz

what is the Hz range for Theta waves?

3.5-7.5 Hz

what is the Hz range for Delta waves?

<4 Hz

what waves are most common in a wakefulness state?

alpha and beta waves

what are the waves most common in stage 1 sleep?

theta waves

how long does stage 1 (falling asleep) last?

around 10 minutes

what are the 2 characteristics of stage 2 sleep?

sleep spindles and K-complexes

what stages are sleep spindles in?

2, 3 and 4

what waves are characteristic of sleep stage 3 and 4?

delta waves

what is the name for stages 3 and 4 of sleep?

slow wave sleepi

in what stages does the body repair from the activity the brain did throughout the day?

stages 3 and 4

what stage does REM resemble on an EEG?

wakefulness

what wave types are common in REM, aside from desynchrony?

beta and theta waves

what happens to the muscles in REM sleep?

loss of muscle tone- paralysis

how long does a sleep cycle last?

90 minutes

what is the brainstem reticular formation?

a group of dozens of nuclei running through the medulla, pons and tegmentum

what are the two types of acetylcholinergic neurons?

one based in the metencephalon and the basal forebrain

when is acetylcholinergic neurons most active?

when the brain is in arousal mode- wakefulness and REM sleep

where is the metencephalon located?

the reticular activating system in the pons

where is the basal forebrain located?

the telencephalon

where do noradrenergic neurons come from?

the locus coeruleus (in RAS in pons)

what is noradrenergic neurons related to?

vigillance induced by external stimuli

when is noradrenergic neurons most active?

during wakefulness

where does serotonergic neurons come from?

the raphe nuclei (RAS in pons and medulla)

what do serotonergic neurons influence?

locomotion and cortical arousal, not sensitive to external stimuli

what is the progression on the activity of serotonergic neurons during the stages of sleep?

drops slowly when moving from wakefulness to slow wave sleep, low during REM

where are histaminergic neurons located?

in the tuberomammillary nucleus in the hypothalamus

when are histaminergic neurons most active?

during wakefulness

where are hypocretinergic neurons located?

the lateral hypothalamus

when are hyporetinergic neurons most active?

during wakefulness

what are the 5 neurotransmitters involved in arousal

acetylcholine, noradrenaline, serotonin, histamine, hypocretin

What waves are specific to the REM sleep

pontine-geniculate-occipital waves

what is the flip-flop system that switches the brain from SWS to REM sleep?

mutual inhibition of the REM ON and REM OFF

whats the fancy name for REM ON

sublaterodorsal nucleus in the dorsal pons

whats the fancy name for REM OFF?

ventrolateral peri-aqueductal gray matter in the midbrain

what is the REM OFF (vlPAG) inhibited by?

the ventrolateral preoptic area (vlPOA)

what is the REM ON inhibited by?

the locus coeruleus and the raphe nucleus

what 3 neurotransmitters need to be low enough for REM sleep to occur?

noradrenaline, serotonin and orexin

what neurons from the lateral hypothalamus activate the REM-OFF part of the brain?

orexinergic neurons

what does REM ON neurons effect that cause EEG changes?

acetylcholinergic basal forebrain

what do the REM ON neurons affect that manage most aspects of rem sleep?

Acetylcholinergic pons

what part of the brain causes penile erection during REM sleep?

lateral preoptic area

what part of the brain causes PGO waves during REM sleep?

the lateral geniculate nucleus in the thalamus

what part of the brain causes rapid eye movements during REM sleep?

neurons in the tectum (mesencephalon)

what part of the brain causes muscle paralysis during REM sleep?

the magnocellular nucleus (medial medulla)

what does the magnocellular nucleus (medial medulla) inhibit?

the spinal motor neurons

what does the activation-synthesis hypothesis describe dreams as a combination of?

external stimuli and internal stimuli

what are the 3 types of control that influence the sleep-wake flip flop system

homeostasis and allostatic and circadian control

what is the neurotransmitter that makes us more tired as we go throughout our day?

adenosine

what process is adenosine a byproduct of?

the breakdown of glycogen stores into glucose by astrocytes

what does an increased amount of adenosine cause?

increased delta activity during slow wave sleep

what effect does adenosine have on neurons?

inhibitory

what are the two hypotheses for adenosine action?

disinhibition of vlPOA and the inhibition of hypocretinergic neurons

what is slow wave sleep affected by?

brain temperature and mental exercise

what is cleared during SWS?

metabolic breakdown products

what does allostatic control refer to?

overriding sleep in case of danger

what are hypocretinergic neurons inhibited by that signals full fat reserves?

leptin and glucose

what are hypocretinergic neurons stimulated by that signals an empty stomach?

ghrelin

what does sensory stimulation activate that causes stress and sleep inhibition?

hypocretinergic and noradrenergic neurons

what keeps our circadian rhythm internally?

the suprachiasmatic nucleus

what cycle to we experience without an SCN

ultradian sleep-wake cycle

what feedback loop retains the sleep-wake cycle?

transcription translation feedback loop

what 2 types of genes are involved in the transcription-translation feedback loop

3 period genes and 2 cryptochrome genes

what genes group with the clock to form a heterodimer?

Bmal1 genes

what does the clock and Bmal1 genes stimulate?

per 1-3 and cryptochrome genes

what does the stimulation of per1-3 genes by the coplex cause?

the making of rNA for transcription

what do cry1 and per1(+3) proteins do?

suppresses the function of clock and Bmal1 in the nucleus

how long is the cycle from high concentration to low concentration within the translation-transcription loop?

12 hours

what do Cry1 and Per2 do within the nucleus?

stimulates the transcription of the Bmal1 which forms the Bmal1 protein

when does SCN activity peak?

the middle of the subjective day

what does the SCN excite through synapses and chemical signals?

the ventral subparaventricular zone

what does the excitement of the vSPZ as a result of the SCN excite?

the dorsomedial nucleus of the hypothalamus

what does the DMH inhibit in response to excitement from the vSPZ?

the vlPOA

what does the DMH excite in response to excitement from the vSPZ?

lateral hypothalamus

what is the curve called that explains how short light pulses can reset the clock?

phase-response curve

what does a light pulse early in the night do?

sets the clock back and lengthens the sleep cycle

what does a light pulse late in the night do?

set the clock forward and shorten the cycle

what receives light signals and passes it to the SCN?

melanopsin-containing retinal ganglion cells

how do the axons of the retino-hypothalamic tract synapse onto the SCN?

glutamate and NMDA receptors

what is the indirect projection from the retina to the SCN via?

the lateral geniculate nucleus

where is melatonin released from?

pineal gland

what does activity in the SCN suppress activity in?

sympathetic superior cervical ganglion

during the subjective night, what does sympathetic activity release that triggers melotonin synthesis?

NA into the pineal gland

what is another name for REM sleep behaviour disorder?

REM without atonia