Exam 3: Sleep Pt 3 Flashcards
sleep is an active state mediated by
- a forebrain system: generates SWS
- brainstem system: activates forebrain to wakefulness
- pontine system (pons): triggers REM sleep
- hypothalamic system : coordinates the other 3 systems
melatonin is produced by ___ in response to___
produced by pineal gland
in response to changes in light
light exposure to retina is relayed by ____ and inhibits ____
relayed by SCN
inhibits melatonin secretion
melatonin secretion is suppressed by
bright light and hence levels increase during the night
what do neurons use as their source of fuel
glucose
when neurons run out of glucose what do they look to?
astrocytes
- provide additional glucose by mobilizing glycogen from storage
what does the process of neurons needing astrocytes since no glucose produce?
adenosine - inhibitory neuromodulator
accumulation of adenosine increases…
delta waves
caffeine
adenosine antagonist
- blocks sleep signals from binding to receptors
acetylcholine system: where are cell bodies located? where do the axons project to?
- cell bodies in basal forebrain and pons (PPN)
axons project to : cerebral cortex and brainstem
activation of Ach neurons produces behavioral activation and ____
cortical dysynchrony
high Ach during __ and __
wakefulness and REM sleep
Ach agonists vs Ach antagonists
Ach agonists: inc arousal
Ach antagonists: dec arousal
Norepinephrine neurons in ___ show high activity in wakefulness and low activity in sleep - zero in REM sleep
Locus Coeruleus (LC)
LC neurons play role in…
vigilance
Raphe nuclei in ____ wake up forebrain
reticular formation
electrical stimulation vs lesions to forebrain
electrical: wakes up animals
lesions: produces persistent sleep
serotonin may suppress what?
processing of sensory information preventing reactions that may disrupt ongoing activities
depression
low serotonin levels - extreme fatigue - not enough serotonin to keep you aroused
histamine cell bodies are located…
in tuberomammillary nucleus of the hypothalamus
where do histamine axons project to?
cerebellum, thalamus, basal ganglia, basal forebrain, hypothalamus
cortical projections histamine
direct increase in cortical activation and arousal
basal forebrain projections- indirect through Ach-ergic neurons
antihistamines
cause drowsiness as a side effect
orexin
neuropeptide
aka hypocretin
where are the cell bodies of orexin located
lateral hypothalamus
where do the axons of orexin project to?
- basal forebrain, raphe nuclei, tuberomamillary nuclues
- strongly excite cholinergic, NE, serotonergic, dopaminergic, histaminergic systems
what does orexin promote and prevent
promote: wakefulness
inhibits: REM sleep
prevents: transition from wakefulness directly into REM sleep
narcolepsy
degeneration of orexin neurons
- or low release of orexin
when they should be awake they randomly fall asleep - struggle to stay alert
flip-flop circuit for sleep
results in sleep OR wakefulness - not both at same time
- brain regions responsible for sleep and awake states are mutually inhibitory
main sleep controller
ventrolateral preoptic area (VLPA)
group of GABA neurons in hypothalamus
VLPA
what does activity in the VLPA suppress and promote?
suppress: alertness and arousal
promotes: sleep
- inc activity during sleep
- dec activity during wakefulness
the constant SWS activity in the forebrain is generated by…
basal forebrain
- activated at onset of sleep, suppresses tuberomamillary nucleus
neurons in the basal forebrain become active at sleep onset and release ______ which suppresses activity in the nearby _____
GABA
tuberomamillary nucleus
what activates the cortex
reticular formation in the brainstem
stimulation vs lesions to the reticular formation
stimulation: wakes up sleeping animals
lesions: produce persistent sleep
what does the reticular formation increase in arousal systems
norepinephrine, serotonin, histamine
what do the basal forebrain and reticular formation seem to guide the brain through
SWS and wakefulness
the VLPA and major wakefulness promoting regions are reciprocally connected by …
inhibitory GABAergic neurons
when the flip flop is in “wake” state arousal systems are ___ and VLPA is ____
active
inhibited
when flip flop is in “sleep” state VLPA is ____ and arousal systems are ____
active
inhibited
what does adenosine buildup disinhibit?
VLPA
adenosine increases sleep pressure to shut down arousal which in turn turns on the ____
VLPA
stabilize sleep/waking flip-flop through excitatory connections with wakefulness neurons
orexin neurons
- constant release of orexin when awake to lock in the aroused state
what brain region triggers REM sleep
the subcoeruleus of the pons
neurons of the subcoeruleus (3 things)
- only active in REM sleep
- inhibit motor neurons to keep them from firing in REM sleep (sleep paralysis, do not move body)
- lesions prevent loss of muscle tone in REM sleep (start to act out dreams in REM - sleep walking)
