Chapter Eight Flashcards
Electromyogram
EMG; records muscle tone
Electro-oculogram
EOG; eye movement
Electroencephalogram
EEG; electrical activity of brain
How many sleep cycles do you go through in a typical night of sleep?
about five
How long does it take to get through one cycle of sleep?
about an hour and a half
Stage One of sleep
10 minutes; theta waves; easily woken up
Stage Two of sleep
K complex; sleep spindles
What are sleep spindles?
thought to be a by product of brain that becomes active during stage two of sleep; filters out distractions/noises that wake you up
Stage 3/4 of sleep
delta waves; stage four is deepest; “slow wave sleep”; most early in the night
which stages does Non-REM take place?
stages 1-4
Does REM get longer with each entry into REM?
Yes
What increases during REM?
eye movement; the 6 eye muscles are the only muscles that move during REM
What happens to muscle tone during REM?
It is lost
What happens to cerebral blood flow during REM?
it increases
How much dreaming occurs during REM?
about 85% (15% nREM)
Refractory period of REM
once awakened, cannot reenter REM for 90 mins; suggests an internal clock regulates this process
Restorative reason for sleep
we need sleep to restore us mind and body; mentally and physically
Cognitive reason for sleep
we need to sleep in order to form memories; brain needs to be removed from constant stimuli
Evolutionary reason for sleep
all humans do this so it must be important. seen as adaptation to benefit survival
Fatal Familial Insomnia
genetic; damage to regions in or near the thalamus
What are the symptoms of fatal familial insomnia?
insomnia, confusion, loss of autonomic NS
What is the life expectancy for fatal familial insomnia?
12 mos. after diagnosis; usually diagnosed in adulthood- mid thirties to forties
What happens to lab animals with lack of sleep?
They will die; prior to death they develop other problems
Complete sleep deprivation
miss one whole night of sleep
Partial sleep deprivation
person sleeps every night but not as much as they should or need
REM deprivation
allow a person to sleep except during REM
Slow wave sleep
allows brain to rest
REM rebound effect
will enter REM more quickly with deprivation; get more REM when deprivation stops
Deprived animal
will lose up to 90% of sleep
“Yoked” control animal
will lose about 30% of sleep; stays healthy
Relationship between exercise and sleep
no clear relationship between the two; working certain brain areas “hard” may result in more slow wave sleep in those areas
Function of REM sleep
critical for brain development; used to consolidate memories; used for learning- if taught task and REM deprived–> learning is slower
How much time do newborns spend in REM?
disproportionate to adults; 50%
Do developed species spend more or less time in REM?
more
Chemical control of sleep
chemicals are involved in sleep, as certain drugs cause drowsiness while others cause sleeplessness; has to be more than chemicals since dolphins can sleep one brain half a time
noradrenergic
in the locus coeruleus (deep in brain stem) when awake they fire, when asleep they stop
acetylcholinergic
in pons which produce cortical activity; agonists increase cortical activity, antagonists decrease it
serotinergoc
in raphe nucleus- fire rapidly when awake, and less rates of firing when asleep
histaminergic
in hypothalamus that increase cortical arousal; antagonists increase drowsiness.
Benedryl an anti-histamine causes drowsiness
Ventrolateral preoptic area (VPL)
found in the forebrain, rostral to hypothalamus ; increase in firing due to slow wave sleep
What happens to rats with a lesion in their VPL?
it produces insomnia and later death within three days
Where are the inhibitory GABA connections to in the VPL?
raphe nucleus, locus coeruleus, and mammillary nucleus
What is REM controlled by?
the pons
What is REM sleep preceded by?
PGO waves (pons, geniculate, and occipital) brief pulses of activity
What is the only way PGO waves can be observed?
by putting electrodes into the brain
What do the PGO waves have to do with our dreams?
likely why our dreams are so visual in nature
What is the executive mechanism
Acetylcholine
What do antagonists do to intervals between REM bouts?
lengthen them (90 mins)
What do agonists do to intervals between REM bouts?
shorten them
Do levels of Ach increase or decrease during REM?
increase
Where are the Ach neurons found?
peribrachial area
What do lesions in the peribrachial area do?
reduce REM sleep
REM “flip flop”
neurons in regions are either ON/OFF and both cannot be active at the same time; switches occur very fast which explains why narcolepsy symptoms occur quickly
Insomnia
affects 25% occasionally and 10% chronically; symptoms resemble depression;
Why are meds prescribed not best option for those with insomnia?
tolerance and rebound effect
Sleep apnea
disturbance of breathing while asleep; may occur hundreds of times per evening
Narcolepsy
directly fall into REM sleep..will sleep for 2-5 minutes; stimulant meds and frequent napping
Cataplexy
awake, but complete loss of muscle tone; triggered by excitement; a couple minutes like narcolepsy and then back to normal
Sleep paralysis
a symptom of narcolepsy- paralysis creeps into waking
hypnagogic hallucinations
another symptom of narcolepsy-dream like states invade waking
REM without atonia
loss of muscle tone does not occur during REM-flip flop does not occur; physically and behaviorally act out dreams
What do meds used to treat cataplexy do to those with REM without atonia?
make them worse
REM sleep disorders
narcolepsy, cataplexy, REM without atonia, sleep paralysis, and hypnagogic hallucinations
Biological clocks
predictable changes in physiological function occur in different time intervals (rhythms)
Zeitgebers
time giver; synchronize circadian (daily) rhythms
What is zeitgeber for regulating sleep?
natural light
Where is the sprachiasmatic nucleus found?
found in the hypothalamus
What happens when suprachiasmatic nucleus is lesioned?
many rhythms are disrupted: sleep, wheel running, hormone secretions
rats with this lesion do not show normal sleeping patterns- they sleep sporadically but get the same amount
Where do the projections from the SCN come from?
the retina
What happens when you transplant a SCN?
restoration of the disrupted rhythms
Silver et al. research
transplanted SCN tissue in a semi permeable capsule and it restored the rhythms
Does SCN lesions disrupt breeding cycles?
Yes, which are activated with “day length” in spring
What do SCN lesioned males do differently?
secrete testosterone year round, as opposed to “peaks” during breeding season
Is the pineal gland important to the SCN?
yes, it receives input from the SCN.
melatonin is secreted by pineal, which changes as seasons change (and light exposure changes)
