Neurobiology of sleep

Question 1

EEG records the difference in electrical conductivity between single neurons
T/F

Answer 1

False - signal from single neurons is too small to detect, so use a summation of several neurons in an area

Question 2

________ neurons produce the strongest EEG signal because they are aligned and fire together

Answer 2

Pyramidal neurons

Question 3

Before the invention of EEG, sleep was studied by_______

Answer 3

Observing behaviour

Question 4

Bremer thought that sleep was caused by_______and found MISLEADING evidence for this__________

Answer 4

Sleep caused by a loss of consciousness;
cut top of mid brain - lost all sensory input, low EEG –> deep sleep state;
Cut top of spinal cord - kept some sensory input = conscious

Question 5

Van economo (1930) found that the hypothalamus was a critical structure for sleep; person with insomnia is likely to have ________ whereas someone with day time sleepiness will likely have______

Answer 5

Insomnia - injury to the anterior hypothalamus

Sleepiness - injury to posterior hypothalamus

Question 6

The hypothalamus is located in the________

Answer 6

midbrain

Question 7

the thalamocortical loop involves ________ and moderates ________cycle

Answer 7

reticular formation (mid brain) + thalamus + cx 
sleep wake

Question 8

Why are we less responsive during sleep compared to wake states?

Answer 8

Wake state has regular, rhythmic action –> more obvious when an external stimuli disrupts it. Whereas when it is in sleeping state, the rhythm is ALREADY disrupted = we are less likely to be conscious of another disruption

Question 9

The ascending activation system consists of 2 networks__________

Answer 9

Cholinergic system + monoaminergic system

Question 10

The cholinergic system regulates ____________

Answer 10

is responsible for the RHYTHMICITY, activation causes EEG DE-synchrony

Question 11

The monoaminergic system is responsible for_________

Answer 11

Providing many inputs to the cortex to KEEP IT IN WAKE STATE

Question 12

What are the 4 major monoaminergic inputs of the ascending activation system?

Answer 12

DA
5-HT
Histamines
Norepinepherine

Question 13

In studies of arousal / cogmntive function the NT looked at MOST is;

a) DA
b) 5-HT
c) Norepinepherine
d) GABA

Answer 13

C - norepinepherine

Question 14

NA is generated WHERE? and is released when encountering______

Answer 14

Locus coeruleus; when faced with stressor NA gets released = incr arousal

Question 15

A lesion to the locus coeruleus will make Jimmy_________

Answer 15

Have INCR slow wave sleep + less aroused

Question 16

Like NA, 5-HT is _________in wake state, _____ in NREM, and _______in REM

Answer 16

Wake - highly active
NREM - less
REM - off

Question 17

5-HT are produced in _________

Answer 17

Raphe nuclei

Question 18

SSRI’s affect sleep by_________

Answer 18

inhibiting reuptake of 5-HT –> INCR wakefulness + decease REM

Question 19

Antihistamines affect sleeping cycle

T/F

Answer 19

FALSE - only affect sleep LATENCY, not sleep itself = affect waking cycle

Question 20

Histamines are created WHERE?

Answer 20

tuberomammillary neurons

Question 21

where is DA created?

Answer 21

Substantia nigra

Ventral tegmental area

Question 22

INCORRECT one is;

a) DA is concentrated in the substantia nigra
b) DA neurons don’t change firing rate across sleep/wake cycles
c) that DA increases when person stays awake for long periods
d) modafinil - drug acting on ]DA-ergic system improves cognitive function in sleep deprived clients

Answer 22

A - DA is widespread across the brain

Question 23

Lesion to the input areas for the thalamocortical loop will induce sleep T/F

Answer 23

FALSE - they are all important for wakefulness but are not CAUSALLY linked –> can induce sleepiness, but NOT sleep

Question 24

UNTRUE about orexin;

a) it is important for stabilisation of wakefulness
b) it is synthesised in the thalamus
c) destruction of orexin p/way causes devastating effects ion wakefulness
d) is important for metabolism / eating

Answer 24

B - is synthesised in the lateral HYPOTHALAMUS

Question 25

What evidence d we have for role of orexin in wakefulness? metabolism?

Answer 25

Wakefulness - orexin / its receptors are DEFICIENT in those with narcolepsy metabolsim - those with narcolepsy eat LESS but have a greater BMI --> linked

Question 26

Orexin is associated with _________ wakefulness behaviours

Answer 26

Reward system + food seeking

Question 27

Lesion to the lateral hypothalamus induces sleep | T/F

Answer 27

False - orexin not CAUSALLY linked, will only make you SLEEPY

Question 28

What is meant by an 'ascending neural system?

Answer 28

Info goes up into more complex areas of the brain to generate wakefulness

Question 29

Why do we have SEVERAL wake systems instead of ONE universal one?

Answer 29

Bc being 'awake' is not in itself a function for survival, we need to seek reward, seek food, reproduce, etc., = separate systems for each goal

Question 30

Cholinergic system involves LTD+PPT, these are both ______during wake/REM states and _______ during NREM

Answer 30

ACTIVE in wake/REM | Low in NREM

Question 31

Blocking cholinergic neurons with drugs causes________

Answer 31

cholinergic neurons send signal for AROUSAL --> blocking with drugs = induce sleep

Question 32

the *updated* version of the wake system's BACKBONE involves which NT's? Destcruction of these areas will be_________

Answer 32

GABA (inh-ory) glutamate (exc-ory) DA Destruction = INDUCE SLEEP

Question 33

The wake system has 4 major systems;

Answer 33

a) cholinergic system b) monoaminergic system c) orexinergic system d) backbone

Question 34

We have 3 major sleep centres_________

Answer 34

1) ventralateral preoptic area (VLPO) 2) median preoptic nucleus 3) parafacial zone

Question 35

INCORRECT about VLPO is; a) it is the on/off switch for sleep b) it is located in the posterior hypothalamus c) Lesion to VLPO decrease in REM sleep d) has GABA + galanin projections that spread to all awake centres

Answer 35

B - it is located in the ANTERIOR hypothalamus. Is on during sleep --> if can't turn it on = insomnia.

Question 36

There is no 'switch' for waking/sleeping state | T/F

Answer 36

FALSE - VLPO is sleep switch

Question 37

The media preoptic nucleus is related to ________ stgae of the 2 process model and has highest activation in ___________

Answer 37

Homeostatic sleep load, regulates sleep. | Highest activation in evening --> when sleep load HIGH, falls during sleep when sleep debt is paid off

Question 38

The parafacial zone works to inhibit_______ part of the wake system

Answer 38

the backbone

Question 39

The wake maintenance zone occurs when_________

Answer 39

the sleep load is at its highest so the circadian system fights it by peaking at this time = high alertness between 6/9pm

Question 40

Sleep regulation is governed by the actions of ___________

Answer 40

SCN - via indirect pathways (bc sends signals to sub par ventricular zone, DMH)

Question 41

If the SCN receives inhibitory input, the outcome will be_____

Answer 41

Inducing sleep bc DMH sneds inh signal --> GABA --> switching on VLPO = sleep

Question 42

If the SCN receives excitatory input, the outcome will be_____

Answer 42

DMH will send exc input to glutamate = orexinergic systems activate = WAKE state

Question 43

Why do we look for objective markers of sleepiness?

Answer 43

safety i.e. driving, work safety

Question 44

The two markers of heostatis sleep drive are_______

Answer 44

1) Adenosine levels in forebrain | 2) SWS

Question 45

As the night progresses, we have ______SWS. The longer we are awake, the ______ we have SWS; therefore a nap will _______ the amount of SWS.

Answer 45

As the night progresses, we have LESS SWS. The longer we are awake, the MORE we have SWS; therefore a nap will DECREASE the amount of SWS.

Question 46

What does the synaptic homeostasis suggest about learning

Answer 46

We learn new stuff every day = make new synaptic connections To incr efficiency, reduce space, SWS does SYNAPTIC DOWNSCALING to reduce number of connections = reducing intensity of connections may actually STRENGTHEN important signals by reducing NOISE

Question 47

SWS occurs across all regions of the brain simultaneously T/F

Answer 47

FALSE - occurs in the areas used most that day, most SWS occurs in the PFC

Question 48

Local sleep refers to____________

Answer 48

Sleep occurring in ONE area of the brain and not another. May occur both in waking and sleeping states

Question 49

Sleep is a spatially and temporally uniform process | T/F

Answer 49

False

Question 50

Adenosine is a biomarker of SWA, it ______ during wakefulness and _______ in sleep.

Answer 50

RISE in day, FALLS in sleep. | Builds up during the day in forebrain

Question 51

Caffeine is an adonosine antagonist, this means_______

Answer 51

it takes up adenosine's receptors and blocks their effect --> keeps you ALERT

Question 52

The Sleep promoting regions are________

Answer 52

VLPO, parafacial zone, Median preoptic area