Chapter 9: PSYCHOLOGICAL MECHANISMS OF SLEEP

Question 1

How is sleep chemically controlled?

Answer 1

Body produces sleep-promoting substance accumulated during wakefulness and destroyed during sleep

Question 2

What does a REM sleep deprivation produce?

Answer 2

Independent REM sleep debt

Question 3

What is the hypothesis on substance release during sleep?

Answer 3

There may be two substances, one for each stage of sleep

Question 4

What is adenosine?

Answer 4

A neurotransmitter released by neurons engaged in high levels of metabolic activity.

Question 5

What role may adenosine may?

Answer 5

role in initiation of sleep

Question 6

What does adenosine do?

Answer 6

Accumulates during wakefulness and is reduced during SWS

Question 7

What does caffeine do to adenosine receptors

Answer 7

caffeine blocks adenosine receptors

Question 8

How is arousal controlled neurologically?

Answer 8

circuits of neurons secrete at least five different neurotransmitters involved in animal’s level of arousal

Question 9

What are the five neurotransmitters that are involved in the level of arousal?

Answer 9

• acetylcholine
• norepinephrine
• serotonin
• histamine
• orexin

Question 10

How is acetylcholine organized to regulate arousal?

Answer 10

3 groups of ACh, each act in different places

Question 11

What do the first two group of ACh do?

Answer 11

produce activation and cortical desynchrony when activated

Question 12

Where do the first two groups of Ach act?

Answer 12

• one in the pons

- one in the basal forebrain

Question 13

What does the third group of ACh neurons do and where does it act?

Answer 13

• controls activity of hippocampus

- located in medial septum

Question 14

How does the ACh release evolve in the cortex?

Answer 14

High during waking, decreases during SWS and increases during REM sleep

Question 15

How does Ach release evolve in the hippocampus?

Answer 15

Medium during waking, decreases during SWS, increases significantly during REM sleep

Question 16

Ach pathways

Answer 16

See with video

Question 17

What do catecholamine (norepinephrine) agonists produce ?

Answer 17

arousal and sleeplessness

Question 18

What does the locus coeruleus contain?

Answer 18

group of NE cells bodies

Question 19

Where is the locus coeruleus located?

Answer 19

in pons near rostral end of floor of the fourth ventricle

Question 20

What is the function of the locus coeruleus?

Answer 20

-Give rise to axons that branch widely
-releases Ne through
neocortex, HIP, thalamus, CC, pons and medulla

Question 21

What happens when a neuron is activated in LC?

Answer 21

increases animal’s vigilance

Question 22

How does Ne rate of firing evolve through stages of sleep and waking?

Answer 22

It is high during waking and decreases as you progress to SWS and REM sleep and then in peaks back up when waking up again

Question 23

Ne pathways

Answer 23

See slide 33+ video

Question 24

What does serotonin (5-HT) play a role in?

Answer 24

plays a role in activating behavior

Question 25

Where are 5-HT neurons found?

Answer 25

in raphe nuclei

Question 26

Where do 5-HT axons project to ?

Answer 26

thalamus, HYP, basal ganglia, HIP, neocortex.

Question 27

How does 5-HT rate of firing evolve through stages of sleep and waking?

Answer 27

3 spikes/sec during active waking, decreases as you progress through SWS and peaks back up when reaching REM sleep

Question 28

5-HT pathways

Answer 28

see slide 36 and video

Question 29

What is the role of histamine?

Answer 29

Fourth NT implicated in control of wakefulness and arousal

Question 30

What is histamine synthesized from?

Answer 30

compound synthesized from amino acid histidine

Question 31

Where is histamine found?

Answer 31

in tuberomammillary nucleus (TMN)

Question 32

What is the tuberomammillary nucleus (TMN)?

Answer 32

Nucleus in ventral posterior HYP, just rostral to mammillary bodies

Question 33

What type of orexin activity was observed in rats during sleep or waking?

Answer 33

- Orexin neurons fired at high rate in rats during alert or active waking - Highest rate of firing seen during exploratory activity. - Low rate during quiet waking, SWS, and REM sleep.

Question 34

What is narcolepsy most often treated with?

Answer 34

modafinil

Question 35

How does orexin and histamine rate of firing evolve through stages of sleep and waking?

Answer 35

High during waking, decreases as you progress to SWS and REM sleep, low during SWS and REM sleep, goes back up when waking up again.

Question 36

Summary of chemical control

Answer 36

See slide 40

Question 37

What three factors is sleep controlled by?

Answer 37

- control of sleep is homeostatic - conscious attempt to control sleep is allostatic - circadian factors restrict sleep to a/ night cycle

Question 38

What does homeostatic mean?

Answer 38

Any process that living things use to actively maintain fairly stable conditions necessary for survival.

Question 39

What does allostatic mean?

Answer 39

the process of maintaining homeostasis through the adaptive change of the organism's internal environment to meet perceived and anticipated demands.

Question 40

What does the sleep/Waking flip-flop control once we fall asleep?

Answer 40

controls our cycles of REM sleep and SWS.

Question 41

sleep waking flip flop

Answer 41

See diagrams slide 44-45

Question 42

How do orexinergic neurons control SWS?

Answer 42

they receive inhibitory input from the vlPOA

Question 43

How does sleep occur in regards to orexinergic neurons?

Answer 43

- sleep signals arise from accumulation of adenosine - eventually overcome excitatory input to orexinergic neurons - sleep occurs

Question 44

What do acetylcholinergic neurons do?

Answer 44

- Play important role in cerebral activation during alert wakefulness - Are involved in neocortical activation that accompanies REM sleep

Question 45

How high is the rate of cerebral metabolism during REM sleep and waking?

Answer 45

As high during REM sleep and waking

Question 46

How would level of physical activity be during REM sleep without state of paralysis?

Answer 46

level of physical activity would also be high

Question 47

According to previous findings, what do ACh neurons of dorsal pons serve as in REM sleep?

Answer 47

Serve as trigger mechanism that initiates period of REM sleep.

Question 48

What does recent research suggest that REM sleep is controlled by?

Answer 48

controlled by activity of flip-flop whose elements do not include ACh neurons.

Question 49

What does the REM flip-flop consist of?

Answer 49

REM-ON neurons and REM-OFF neurons

Question 50

Where are REM-ON neurons situated?

Answer 50

Sublaterodorsal nucleus (SLD)

Question 51

Where are REM-OFF neurons situated?

Answer 51

Ventrolateral periaqueductal gray matter (vlPAG)

Question 52

Where is the peribrachial area situated?

Answer 52

Region around brachium conjunctivum, located in dorsolateral pons.

Question 53

What does the peribrachial area do?

Answer 53

Contains ACh neurons involved in initiation of REM sleep

Question 54

How does a REM-ON cell fire through waking, SWS and REM sleep?

Answer 54

Almost 0 firing during waking and SWS, slowly increases during Pre-REM sleep, very high firing during REM sleep

Question 55

REM sleep flip flop diagram

Answer 55

See slide 52

Question 56

Control of components of REM sleep by the REM-ON region

Answer 56

see diagram slide 53

Question 57

According do investigators, what does a loss of orexinergic neurons result in?

Answer 57

Removes an inhibitory influence of HYP on AMYG

Question 58

What could increased AMYG activity account for?

Answer 58

- At least in part | - Increased activity of REM-ON neurons that occurs even during waking in people with cataplexy

Question 59

Humour and narcolepsy diagram

Answer 59

slide 56