Sleep-ARS Flashcards
What are the basic EEG rhythms or patterns, and the changes that occur during a seizure?
Absence seizure - spike-wave
Complex partial - (focus where it starts) very small crazy amplitudes
What is an EEG?
Electroencephalography
Non invasive measurement of brain activity
What are the stages of sleep?
Awake
Drowsy
What are the patterns of sleep and the EEG that patterns that characterize them?
- Awake - alpha waves
- Stage I (drowsy) - beta waves
- Stage II - sleep spindles (higher amp and freq, onset of coherence, driven by Thalamiccortical oscillations)
- Stage III - theta?
- Stage IV - delta
- REM - very much like awake, essentially beta waves
What are the patterns of sleep and the EMG that patterns that characterize them?
Waking - high muscle tone
Non-REM - highish muscle tone
REM - almost no muscle tone
What are the patterns of sleep and the ELectrooculogram that patterns that characterize them?
- Waking - Saccades (random peaks, high freq)
- Non REM - rolling motion of eyes (medium amplitude highish freq)
- REM - Saccades come back (big peaks, low freq)
What are the circuits responsible for sleep/wake transitions, including the ascending reticular activating system and the region that promote slow-wave sleep?
ARAS - nuclei from the braimstem (pontine nuclei), hypothalamus, basal forebrain –> cortex and thalamus
What are the possible functions of sleep?
Reducing energy expenditure Replenish brain glycogen Cognition - brain plasticity - consolidation, memories, association, - consolidation of learning Possibly allows shrinkage of neurons and metabolizes to be drained out
What are the effects of sleep deprivation?
Short term: cognitive impairment - reaction time - judgment Long term - cognitive decline (dementia) - Problems with homeostasis - infection - hallucination, seizures - death REM sleep is not necessary Stage III and IV is necessary
What is the relationship between the functions of sleep disturbances and other clinical disorders?
A
How does an EEG work?
Works by receiving the electric field of pyramidal cells on the cortex
What is the big dip in and EEG normally?
Eye blinks
What are the axis for EEG?
1sec - x
100uV - y
What are beta waves on a EEG?
Tiny peaks becaus you get lots of info in that cancel each other out, also why the frequency is high because things are in sync
Active thinking
Freq 12-30
Amp 30
What are alpha waves on an EEG?
Eyes closed
Less info coming in
Larger regions of the cortex are being activated together so you get larger amplitudes but a lower frequency
Freq - 8-12
Amp - 10-50
What are theta waves on an EEG?
Drowsiness or meditation
Freq - 4-8
Amp - 50-100
What are delta waves on an EEG?
Slow-wave sleep
Freq less than 4
Amp - 100-150
Is coherence in cortical states a good thing?
Not always, that is a seizure
Very coherent spike-wave repeat
Absence seizure - eye blinking, loss of consciousness
What is driven by Thalamocortical oscillations?
Sleep spindles in stage II
What stage of sleep is restorative?
Stage four
What do you see with sleep apnea?
When you lose tone in the palate it collapes
Stay mostly awake
What are the two tracts that project into the sleep wake cycle?
Thalamocortical
Corticothalamic
What give you the particular EEG patterns?
Firing from the Thalamocortical and corticothalamic tracts
What does the ARAS use for transmission?
Monoamines
ACh
What are the monoaminergic nuclei and what do they produce?
Tuberomammillary nucleus - HA
SN/ventral tegmental area - DA
Locus ceruleus - NE
Raphe nuclei - 5-HT
What neurotransmitter is related to wakefulness?
Histamine
What are the Cholinergic nuclei?
BF - basal forebrain
LDT - laterodorsal tegmental nucleus
PPT - pedunclopontine tegmental nucleus
What does the ARAS promote?
Wakefulness
What are the ARAS nuclei that mainly project to the thalamus?
LDT and PPT
What is the function of the ARAS nuclei?
Modulate the cortex
What are the two different lateral hypothalamus neurons?
Orexin (hypocretine)
MCH (REM sleep)
Both neuropeptides
What is orexin?
Sustains wakefulness and projects to all ARAS nuclei
What happens when you lose orexin?
Narcolepsy
Parietal loss in Parkinson’s and brain trauma
Orexin antagonists may be used as sleep aids
What does the preoptic nuclei do?
Two of them:
VLPO
MNPO
Promotes sleep
What neurotransmitters does the preoptic nuclei (VLPO, MNPO) have?
GABA and galanin
Where does the preoptic area project?
ARAS and orexin neurons and inhibits them
Where does the Thalamocortical circuit project from the thalamus?
Th thalamic reticular nucleus. Wraps around the whole nucleus.
INHIBITORY and the others are excititory
What contributes to sleep spindles and waves?
He Thalamocortical circuit
Do you dream during non-REM sleep?
Less frequent, vivid, and emotional than during REM
Less memorable
What is bursting mode of the thalamus?
Reticular cell fires in a burst –> inhibits Thalamocortical cell (hyperpolarization) –> bursts of action potentials –> excites pyramidal cell in cortex –> cortex projects back to thalamic cortical cell and prevents burst (depolarized) and also fires to the reticular cell and makes a cycle
This leads to coherent activity in the cortex. This is how we get slow sleep
What happens during REM sleep?
The preoptic nuclei a subset stops inhibits the LDT and the PPT which allows sensory transmission to the cortex (some sensory)
Leads to dreams
What area of the brain is inhibited during REM and what does it do?
Dorsaolateral prefrontal cortex
Gives impulse control and judgment (social control)
What does the anterior cingulate cortex do?
Smilingly emotional facial expression
What does the parahippocampal gyrus do?
A lot with memory
What gives you beta waves during rem?
Subset of LDT/PPT (rem on)
What is the REM off switch?
LC/Raphe (part of ARAS)
What may be the first symptom of Parkinson’s and levy body dementia?
REM behavior disorder
What is REM behavior disorder?
Loss of rem atonia
More common in old people
80% of Pxs later develop alpha-synucleinopathies
What are the REM on neurotransmitters?
ACh and MCH
What are the rem-off neurotransmitters?
Monoamines
What neurotransmitter is present during REM and waking?
ACh
What neurotransmitter is present only during waking?
Orexin
What neurotransmitters are the monoamines in sleep-wake cycle?
Serotonin
NE
DA
HA
What has orexin?
Lateral hypothalamus
What does the lateral hypothalamus have?
MCH and orexin, waking and rem
What metabolizes are cleared during sleep?
Beta amyloid
What is the “somnogen” hypothesis?
Accumulation of diffusable or circulating factors promotes sleep
- adenosine is one possible somnogen
(Byproduct of ATP use –> binding inhibits ARAS
–> dis inhibition of VLPO(sleep switch) –> sleep
What does caffeine do?
It is an antagonist of adenosine receptors
What does the preoptic nuclei release?
GABA and galanin make you sleep
