EEG and Sleep - Karius Flashcards
Gene activation/protein products set the circadian rhythm
Within the nucleus of SCN neurons
Clock (CLK)
BMAL1 - increase at night
Increase transcription/translation of: Period genes (Per1-3) Crytpochrome gene (Cry1-2)
Products inhibit Clock and BMAL1
Retina-Hypothalamic tract
light/dark information
- not vision
- use cryptochrome receptors
direct relay to hypothalamus, does not use visual cortex
Glutamate - daylight
Melatonin - darkness
Natural circadian clock
about 25 hours long - rough estimate
Hypothalamus role
controls circadian rhythm and sleep induction/arousal separately
Non-REM
Most time asleep is non-REM
Stages: 1, 2, deep
Progressive slowing of EEG waves
Dreams - rehashing days events, not remembered
REM sleep
rapid eye movement
EEG: low amplitude, higher frequency waves
- eyes moving rapidly left/right
- Associated with vivid dreams that you remember
Inducing sleep
Sleep homeostasis - need for sleep
-NREM sleep
Circadian clock tries to match need for sleep to darkness
Circadian clock triggers REM sleep
Ventral Preoptic Area (VPO) crucial
Mechanism of homeostatic need for sleep
PGD2 in blood bind to DP receptor on endothelial cell of capillary –> release of adenosine from cell into the CSF
accumulation of adenosine throughout day - tired feeling
Adenosine bind to 2a receptors in Ventrolateral Preoptic area (VPO)
Induction of sleep at non-REM level
IL1b, TNFa
NFkB released –> NO synthase –> NO
Tired when sick
Growth spurt induction of non-REM sleep
GHRH triggers growth during sleep
NFkB released –> NO synthase –> NO
Initiation of REM sleep
Lateral pontine tegmentum
-Cholinergic neurons
Axons to geniculate body - release Ach
-sends input to occipital cortex
Muscle paralysis in REM sleep
crucial to prevent muscle activation during dreams
Locus Ceruleus - descending inhibition to alpha-motoneurons
- effective on large muscle groups
- spares diaphragm and small muscle groups
Inducing arousal
lateral hypothalamus - orexin A and B (hypocretin 1 and 2)
orexigenic input sent to tuberomamillary nucleus (histamine)
Histamine released in locus ceruleus binds to H1 receptors, activating the LC neurons
-release NE and suppress REM sleep
EEG - general features
Low voltage less than 200 uV
Frequency less than 1 Hz to more than 50 Hz
Differs over different parts of brain
Changes with degree of activity in the brain, arousal/awareness, sensory input.
No distinct “pattern”
Clear “patterns” pathological - seizure
Alpha waves
8-13 hz
50 uV
quiet wakefulness - thinking with eyes closed
most prevalent over occipital cortex
disappear during sleep
Origin:
- requires connection between thalamus and cortex
- GABAergic neurons “force” coordination of neuronal activity
- feedback oscillation between thalamus and cortex creates waves