topic 6: sleep

Question 1

what is an eeg?

Answer 1

surface electrons that collect the signals as a summation of activity. Synchronised activity and unsynchronised activity.

Question 2

When someone is awake there is…

Answer 2

desynchrony. stage 1 sleep- eyes still open and transitioning. stage 2: sws- larger waves- where the brain recovers.

Question 3

what is rem

Answer 3

rapid eye movement sleep, the brain is verya ctive and there is a loss of muscle tone.

Question 4

during arousal what areas of the brain are involved

Answer 4

the brainstem reticular formation, group of nuclei running through the medulla, pons and tegmentum. some of these make up the reticular activating system.

Question 5

acetycholinergic

Answer 5

long axons that go all over the brain, influence the cortex, the EEG will look like your awake. need this to be awake, it is low during sws.

Question 6

noradrenergic: where is it produced and what does it do

Answer 6

found in locus coeruleus in RAS in teh PONs: active during vigilane and startled (external vigilance)- high when we are awake and continuously drops and is at 0 during REM sleep- crucial condition for REM.

Question 7

serotonergic: what is it and where is the NT

Answer 7

higher when we are waking up- incompatability between REM and sleep. nuclei called raphe- release serotonin across the brain. it focuses on vigilance towards internal sitmuli like our own motivation.

Question 8

histaminergic: where and what

Answer 8

used by tuberomamillary nucleus (hypothalamus)- high when awake and low when sleeping. anti histamines put you to sleep if it passes blood-brain barrier.

Question 9

hypocretinergic: where and why

Answer 9

orexin and in the lateral hypothalamus. it increases activity in other areas like LC , RN and TM- it activates all the other areas that keep us awake. active during active waking and exploration.

Question 10

what is the flip flop system:

Answer 10

when VLPA is active it prevents wakefulness from firing so we will not be alert- quick transition between both.

Question 10

ventrolateral peroptic area

Answer 10

hypothalamus and connects through gaba synapses to wakeful areas. it recieves inhibitory inputs from these brain areas.

Question 11

the Rem ON sits…

Answer 11

on the Pons

Question 12

the REM off sits on…

Answer 12

the vPAG and there is mutual inhibition between both.

Question 13

when we fall asleep REM off…

Answer 13

becomes less active and makes it possible for the REM on area to take over.

Question 14

REM on is also inhibited by…

Answer 14

LC and Raphe- REM begins when the inihibitions are slowly lifted.

Question 15

REM areas affect…

Answer 15

acteycholinergic basal forebrain- the acetycholinergic pons which activates the lateral preoptic area- penile erection, activates areas in thalamus, neurons in tectum which leads to the rapid eye movements.

Question 16

what is the activation synthesis hypothesis?

Answer 16

brain interprets things as scenes, external infrmation can enter dream, brains try to interpret it as a story, there are no functions to dream.

Question 17

the sleep wake flip flop is influenced by…

Answer 17

homeostatic control.

Question 18

what are the controls of sleep

Answer 18

homeostatic, allostatic and circadian control.

Question 19

what is homeostatic control?

Answer 19

adenosine- produced by astrocytes, increased levels cause more activity during SWS. adenosine has inhibitory effects which stop release of action potention.

Question 20

what does stopping the production of adenosine result in?

Answer 20

disinibit the vLPOA- more likely to flip and favour sleep. Also inhibits hypocrinetgic neurons (which activate other areas of the alert system).

Question 21

what is allostatic control:

Answer 21

over ride in case of danger. Threats to survival promote wakefulness: Hunger and Stress.

Question 22

what is the allostatic controls response to hunger?

Answer 22

hypocretinergic neurons inhibited by leptin and stimulated by ghrelin.

Question 23

what is leptin?

Answer 23

neruons increase activity in lateral hypothalamus which keeps us awake- it signals fat reserves and glucose.

Question 24

what is ghrelin?

Answer 24

a hormone that signals an empty stomach.

Question 25

what is the allostatic control's response to stress?

Answer 25

areas for stress stimulate parts of arousal system (hypocretinergic and vigilance neurons). Medial prefrontal cortex has excitatory synapses here- corticotropin releasing factor from amygdala also excites these neurons.

Question 26

what is circadian control?

Answer 26

day-night cycle, so 24 hour biological rhythm.

Question 27

what is the endogenous (internal) clock:

Answer 27

suprachiasmatic nucleus (SCN- in the optic chaism and sits close to the optic nerves)- without this we experience an ultradian cycle.

Question 28

what are the hamster transplant findings suggest?

Answer 28

strain of genes where hamsters had a 20 hour biological clock- if reimplanted with a 24 hour clock the hamster than has that 24 hour clock.

Question 29

what are the cogs of the endogenous clock?

Answer 29

3 period genes, 2 cryptochrome genes and clock & Bmal 1 genes.

Question 30

what is meant by reading the molecular clock?

Answer 30

SCn peaks at mid-day, gene expression cycles must somehow interact with the membrane- evidence for these feedback loops.

Question 31

protein levels are offset by...

Answer 31

mRNA levels by roughly 6 hours.- this peak in protein corresponds to a drop in mRNA.

Question 32

# from SCN to flip flop Scn excites what zone...

Answer 32

ventral sub paraventricular zone- a key relay station in the sleep cycle.

Question 33

the VSPZ excites...

Answer 33

the dorsomedial nucleus of the hypothalamus and the DMH inibits the vLPOA (more likely to favour sleep side).

Question 34

the role of SCN on jet lag

Answer 34

trying to fall asleep when SCN is in another time zone- subjective clock- the SCN is still active in subjective day.

Question 35

how do we adjust to jetlag?

Answer 35

lab hamsters are nocturnal and their activity follows a pattern- with a constant dim light the activity periods shift along with their endogenous clocks.

Question 36

what are zeitgebers

Answer 36

time-givers that entrain our internal rhythm with our external rhythm. for example, light food and sounds.

Question 37

light pulses can...

Answer 37

reset the clock, light early in the night sets clock back and light late an in the night moves clock forward.

Question 38

what is the phase response curve:

Answer 38

found that light pusle few hours into subjective night doesnt affect current night but the night after as activity starts at a later time, clock is set back and lengthened the one cycle.

Question 39

how do you reset the clock?

Answer 39

direct projection from retina to SCN. In the retina there is melanopsin (retinal ganglion cells which are photoreceptors), the retinal ganglion cells have direct synpase onto the SCN which sits newar optic chiasm.

Question 40

what is melanopsin responsible for...

Answer 40

resetting or synchronising with the outside world, they are light detecting cells within the brain.

Question 41

what are the mechanisms behind resetting our biological clocks?

Answer 41

retinal hypothalamic tract axons synapse onto SCN- usign glutamate onto NDMA receptors. when binds calcium will go into SCN neuorns and an influx in calcium increases gene transcription.

Question 42

melatonin is...

Answer 42

released from the pineal gland and sits on top of the hypothalamus it is a hormone that is influenced by the SCN.

Question 43

while the SCN is active during

Answer 43

subjective day it does not release melatonin and that is suppressed and during subjective

Question 44

during subjective night...

Answer 44

sympathetic activity release NA onto pineal gland which triggers de novo synthesis of melatonin which is released into the blood stream.

Question 45

the release of melatonin allows...

Answer 45

all cells to remain in time with each other including SCN, when melatonin inhibits the SCN it can also shift your biological clocks.

Question 46

shifting your biological clock...

Answer 46

signals dark things instead by telling the SCN to not fire potentials due to the light and the melatonin blocks SCN from suppressing the melatonin.

Question 47

what is insomnia?

Answer 47

struggle to fall asleep: different sleep requirements, overrestimation of occurence, worsened with sleeping pills and sleep apnea.

Question 48

what is narcolepsy?

Answer 48

sleep paralysis- happens between awake and slow wake sleep, hypnagogic hallucinations.

Question 49

REM sleep behaviour disorder

Answer 49

in rem sleep but paralysis is not working, they act out their dreams- could be from dama to the manglia nucleus.

Question 50

slow wave sleep problems

Answer 50

bed wetting, sleep walking, night terrors and sleep-related eating disorders.

Question 51

jet lag

Answer 51

disparity between internal and external rhythms. different rhythms are out of synch with each other, disappears slowly over time by entrainment to new environment. can be treated with melatonin.