Chapter 9: PSYCHOLOGICAL MECHANISMS OF SLEEP Flashcards
How is sleep chemically controlled?
Body produces sleep-promoting substance accumulated during wakefulness and destroyed during sleep
What does a REM sleep deprivation produce?
Independent REM sleep debt
What is the hypothesis on substance release during sleep?
There may be two substances, one for each stage of sleep
What is adenosine?
A neurotransmitter released by neurons engaged in high levels of metabolic activity.
What role may adenosine may?
role in initiation of sleep
What does adenosine do?
Accumulates during wakefulness and is reduced during SWS
What does caffeine do to adenosine receptors
caffeine blocks adenosine receptors
How is arousal controlled neurologically?
circuits of neurons secrete at least five different neurotransmitters involved in animal’s level of arousal
What are the five neurotransmitters that are involved in the level of arousal?
- acetylcholine
- norepinephrine
- serotonin
- histamine
- orexin
How is acetylcholine organized to regulate arousal?
3 groups of ACh, each act in different places
What do the first two group of ACh do?
produce activation and cortical desynchrony when activated
Where do the first two groups of Ach act?
- one in the pons
- one in the basal forebrain
What does the third group of ACh neurons do and where does it act?
- controls activity of hippocampus
- located in medial septum
How does the ACh release evolve in the cortex?
High during waking, decreases during SWS and increases during REM sleep
How does Ach release evolve in the hippocampus?
Medium during waking, decreases during SWS, increases significantly during REM sleep
Ach pathways
See with video
What do catecholamine (norepinephrine) agonists produce ?
arousal and sleeplessness
What does the locus coeruleus contain?
group of NE cells bodies
Where is the locus coeruleus located?
in pons near rostral end of floor of the fourth ventricle
What is the function of the locus coeruleus?
-Give rise to axons that branch widely
-releases Ne through
neocortex, HIP, thalamus, CC, pons and medulla
What happens when a neuron is activated in LC?
increases animal’s vigilance
How does Ne rate of firing evolve through stages of sleep and waking?
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
Ne pathways
See slide 33+ video
What does serotonin (5-HT) play a role in?
plays a role in activating behavior
Where are 5-HT neurons found?
in raphe nuclei
Where do 5-HT axons project to ?
thalamus, HYP, basal ganglia, HIP, neocortex.
How does 5-HT rate of firing evolve through stages of sleep and waking?
3 spikes/sec during active waking, decreases as you progress through SWS and peaks back up when reaching REM sleep
5-HT pathways
see slide 36 and video
What is the role of histamine?
Fourth NT implicated in control of wakefulness and arousal
What is histamine synthesized from?
compound synthesized from amino acid histidine
Where is histamine found?
in tuberomammillary nucleus (TMN)
What is the tuberomammillary nucleus (TMN)?
Nucleus in ventral posterior HYP, just rostral to mammillary bodies
What type of orexin activity was observed in rats during sleep or waking?
- 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.
What is narcolepsy most often treated with?
modafinil
How does orexin and histamine rate of firing evolve through stages of sleep and waking?
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.
Summary of chemical control
See slide 40
What three factors is sleep controlled by?
- control of sleep is homeostatic
- conscious attempt to control sleep is allostatic
- circadian factors restrict sleep to a/ night cycle
What does homeostatic mean?
Any process that living things use to actively maintain fairly stable conditions necessary for survival.
What does allostatic mean?
the process of maintaining homeostasis through the adaptive change of the organism’s internal environment to meet perceived and anticipated demands.
What does the sleep/Waking flip-flop control once we fall asleep?
controls our cycles of REM sleep and SWS.
sleep waking flip flop
See diagrams slide 44-45
How do orexinergic neurons control SWS?
they receive inhibitory input from the vlPOA
How does sleep occur in regards to orexinergic neurons?
- sleep signals arise from accumulation of adenosine
- eventually overcome excitatory input to orexinergic neurons
- sleep occurs
What do acetylcholinergic neurons do?
- Play important role in cerebral activation during alert wakefulness
- Are involved in neocortical activation that accompanies REM sleep
How high is the rate of cerebral metabolism during REM sleep and waking?
As high during REM sleep and waking
How would level of physical activity be during REM sleep without state of paralysis?
level of physical activity would also be high
According to previous findings, what do ACh neurons of dorsal pons serve as in REM sleep?
Serve as trigger mechanism that initiates period of REM sleep.
What does recent research suggest that REM sleep is controlled by?
controlled by activity of flip-flop whose elements do not include ACh neurons.
What does the REM flip-flop consist of?
REM-ON neurons and REM-OFF neurons
Where are REM-ON neurons situated?
Sublaterodorsal nucleus (SLD)
Where are REM-OFF neurons situated?
Ventrolateral periaqueductal gray matter (vlPAG)
Where is the peribrachial area situated?
Region around brachium conjunctivum, located in dorsolateral pons.
What does the peribrachial area do?
Contains ACh neurons involved in initiation of REM sleep
How does a REM-ON cell fire through waking, SWS and REM sleep?
Almost 0 firing during waking and SWS, slowly increases during Pre-REM sleep, very high firing during REM sleep
REM sleep flip flop diagram
See slide 52
Control of components of REM sleep by the REM-ON region
see diagram slide 53
According do investigators, what does a loss of orexinergic neurons result in?
Removes an inhibitory influence of HYP on AMYG
What could increased AMYG activity account for?
- At least in part
- Increased activity of REM-ON neurons that occurs even during waking in people with cataplexy
Humour and narcolepsy diagram
slide 56
