B7.048 Sleep, Wakefulness, and the EEG Flashcards

1
Q

components of reticular activating system

A
cerebral cortex
thalamic nuclei
-intralaminar nuclei
-thalamic reticular nucleus
pontomesencephalic reticular formation
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2
Q

function of reticular activating system

A

diffuse projecting system
turns on brain
heavily involved in wakefulness and sleep

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3
Q

segments of the reticular formation

A
stuff in between CN nuclei and long tracts
rostral reticular formation
caudal reticular formation
-raphe
-medial (magnocellular)
-lateral (parvocellular)
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4
Q

what is an EEG

A

electroencephalogram
measures electrical activity in brain with sensitive electrodes
produces a graph of voltage (uV) by time

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5
Q

EEG frequency bands

A

beta: >12 Hz
alpha: 8-12 Hz
theta: 4-8 Hz
delta: <5 Hz

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6
Q

2 EEG activities seen during wakefulness

A

B activity, > 20 Hz

a activity, 8-12 Hz

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7
Q

beta activity

A

low amplitude
high frequency
occurs during alert wakefulness
front of brain

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8
Q

alpha activity

A

higher amplitude
lower frequency
relaxed wakefulness with eyes closed
back of brain

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9
Q

distribution of alpha and beta waves over the brain

A

alpha rhythm largest over parietal, occipital, and posterior temporal lobes
alpha replaced by beta when eyes are opened
beta rhythm most prominent in front of brain

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10
Q

current source of EEG

A
cortical neurons
changes in RESTING membrane potentials
-synaptic potentials
-summed EPSP and IPSP
NOT action potentials (too brief)
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11
Q

synchronization of cortical neurons

A

if resting membrane potential oscillations of cortical neurons were independent and random, electrical activity would cancel out
a pacemaker is required to synchronize the oscillations

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12
Q

pacemaker of cortical neurons

A

thalamic reticular nucleus

thalamocortical circuits

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13
Q

how does the thalamic reticular nucleus operate

A

receives excitatory input from the thalamocortical and corticothalamic axon collaterals
neurons are GABAergic

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14
Q

reticular activating system (RAS) input to thalamus (TRN)

A

regulates wakefulness
thalamus synchronizes the oscillations of cortical neurons at different frequencies during wake and sleep
EEG appearance changes

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15
Q

sleep stages

A
awake: a and B
stage 1 (drowsy): a drops out, theta waves
stage 2: sleep spindles and k-complexes
stages 3-4: slow wave sleep, D waves
REM sleep: looks like awake, B waves
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16
Q

REM sleep

A

metabolically active brain

EEG appearance similar to awake EEG

17
Q

brain during non REM sleep

A

less physiologically active

prominent slow waves

18
Q

synchronized waves

A

high amplitude
low frequency waves
sleep spindles, a, and D rhythms

19
Q

desynchronized waves

A

low amplitude
high frequency
b rhythm

20
Q

neuronal physiology during wakefulness and REM

A

neuron depolarizations with short refractory periods

tonic mode

21
Q

neuronal physiology during slow wave sleep

A

stimulus from RAS results in hyperpolarization
post stimulation latency period so that neuron cannot be stimulated again
phasic mode

22
Q

the sleep cycle

A

descends from stage 1, 2, 3, 4 back up to REM and then back down
90 minute cycles throughout the night
REM cycles become longer closer to morning

23
Q

when is a person most likely to spontaneously awake from sleep

A

after a REM cycle

24
Q

changes to the sleep cycle with age

A

older people have less time in slow wave sleep
more fragmented
more waking up

25
physiologic characteristics of slow wave sleep
neuronal activity low, metabolic rate and brain temp at their lowest sym output decreases, HR and BP decline muscle tone low, but present reflexes present
26
physiologic characteristics associated with REM sleep
``` rapid eye movements dreaming high cortical activity irregular changes in BP, HR , and breathing penile erection, clitoral engagement atonia ```
27
explain atonia in REM sleep
active inhibition of alpha motoneurons prevents movements occasional jerky movements escape reticulospinal tract responsible for this inhibition (so you don't act out your dreams)
28
REM sleep disorders
reticulospinal dysfunction muscles don't shut down common in people with dopaminergic issues, may later get Parkinson's
29
diffuse projection systems involved in regulation of wakefulness and sleep
cholinergic noradrenergic serotonergic dopaminergic
30
cholinergic projection system
important component of reticular activating system (RAS) located in basal nucleus of the forebrain, rostral pons, and midbrain tegmentum ACh causes depolarization of forebrain neurons, thus causing cells to discharge in the tonic move which results in desynchronized EEG keeps you awake
31
noradrenergic system
locus ceruleus | wakefulness and REM sleep
32
serotonergic system
median raphe of reticular formation | slow wave sleep maintenance
33
effect of serotonin inhibition drugs
can cause insomnia
34
dopaminergic system
substantia nigra | deficiency: REM sleep disorder
35
circadian rhythm
sleep and wakefulness occur in an approximate 24 hours cycle (25-26ish for most) rhythm is entrained by exogenous stimuli (visual input)
36
circadian rhythm pacemaker
suprachiasmatic nucleus in anterior hypothalamus monitors light/dark cycle receives input from retino-hypothalamic tract
37
retino-hypothalamic tract
light sensitive retinal ganglion cells contain melanopsin | these cells go straight to hypothalamus SCN > pineal gland > melatonin