Chapter 13: Sleep, Dreaming and Biological Rhythms Flashcards
What is a biorhythm and what does it do?
an inherent timing mechanism that controls or initiates biological processes
What is a biological clock and what is interesting about a plant’s?
regulates feeding, sleeping and metabolic rates; they are endogenous
What are the 4 lengths of measurement for biorhythms?
1) Circadian (daily)
2) Circannual (annually)
3) Infradian (more than a day)
4) Ultradian (less than a day)
What happens to humans when their rhythm is left “free-running”? What determines this from species to species?
their rhythm lengthens; depends on light-related biology of the species (if they’re nocturnal it becomes shorter)
What is a zeitgeber and what is an example of one?
an environmental event that entrains biological rhythms; light/light pollution
What are the two types of SAD?
1) Phase retarded: desired sleep earlier in day
2) Phase delayed: desired sleep later in day
What is the “master biological clock” and where is it located in the brain?
the suprachiasmatic nucleus (SCN); in the hypothalamus just about the optic chiasm
What is proof the SCN regulates rhythms and what can help to entrain it’s clock?
still maintains rhythmic activity if all pathways to and from are cut; and is more active during light; regular feeding
What 3 other structures help the SCN in regulating?
the intergeniculate leaflet, raphe nucleus and the pineal gland
What type of synapses are the cells in the SCN connected through? What do they help to do?
inhibitory GABA synapses; keep time in synchrony
Where does the SCN receive light information from?
the retinohypothalamic tract (pRGC)
What compound is in the RGC’s in the retinohypothalamic tract that contributes to the SCN’s abilities? What are 3 substances it is composed of?
melanopsin; glutamate, substance P, pituitary adenylate cyclase
What part of the SCN does the retinohypothalamic tract excite? What does this part do in turn?
the ventrally located core; entrains the dorsally located shells to be rhythmic
What are the 4 steps in the main clock mechanism?
1) Transcription
2) Translation
3) Inhibition
4) Decay
What are the 4 ways for slave oscillators to be entrained?
1) SCN to nuclei in hypothalamus and thalamus (connect extensively with body)
2) Connects with pituitary endocrine (hormone release)
3) Sends indirect info to SC neurons which inhibit melatonin production
4) SCN releases hormones itself
What 2 hormones does the SCN regulate? What setting does it regulate each in?
melatonin (dark); glucocorticoids (light)
What does the SCN affect in other animals in relation to circannual rhythms? Example of Hamster and deer/sheep?
the reproductive behavior; hamster more in summer which is opposite of sheep/deer which is more in fall/early winter
What are the 4 states of waking and sleeping?
1) Waking state
2) Relaxed state
3) Drowsy state
4) Sleeping state
5) REM sleep
6) NREM sleep
What rhythm is associated with the waking state?
Beta rhythm (15-30hz)
What rhythm is associated with the relaxed state?
Alpha rhythm (7-11hz)
What rhythm is associated with the drowsy state?
Theta waves (4-7hz)
What rhythm is associated with the sleeping state?
Delta waves (1-3hz)
How many stages are there of NREM sleep? Which is the deepest?
4; known by some as stage 4 and others by 3b
How long is a typical NREM-REM sequence and how many times does it occur?
90 minutes; 5 times
When during a night’s sleep does more REM vs NREM occur?
more REM at end; NREM at beginning
What happens to your muscles and body temperature during REM sleep?
they lose tone (atonia); body temperature drops
What sleep stage do grinding, flailing and walking occur?
NREM
What did Freud believe dreams are?
symbolic fulfilment of unconscious wishes; manifest (actual) vs latent (true meaning)
What are dreams actually related to? What emotions are most prevalent?
events that happened quite recently and related to ongoing problems; anger, sadness, anxiety
What is the activation-synthesis hypothesis and what does it suggest?
the cortex receives signals from brainstems and generates dreams in response; dreams are meaningless brain activity and all meaning is created afterwards
What theories of dreams approach it as a top down phenomena? What are some reasons it does so in relation to content of dreams?
dreams as a coping strategy; they are biased towards threats which allows for prep and there is more approach behavior
What is a basic rest activity cycle (BRAC)?
recurring cycle of temporal packets around 90min that wax and wane during the day
What does a lack of sleep result in?
poor cognitive function, inability to maintain attention and microsleeps (lasting a second or so)
What are 2 things that happen after REM sleep deprivation?
1) increase tendency to enter REM in subsequent sleep
2) REM rebound for more overall REM in subsequent sleep
What are the 3 phases of memory and what phases does sleep help with?
1) Labile
2) Consolidation
3) Recall
Consolidation and Recall
What is the multiple processes theory of memory and sleep?
different memory types are stored during different stages of sleep
What is the sequential theory of memory and sleep?
memory is manipulated in different ways during sleep states (stored, eliminated etc.)
What is the storage theory of memory and sleep?
brain regions that handle different kinds of memory during waking continue to do so during sleep
What phase of sleep is more associated with explicit memory and which with implicit?
NREM - explicit ; REM - implicit
What system in the brainstem contributes to sleep-wake behavior?
the reticular activating system (RAS)
What does damage to the reticular activating system sometimes result in?
coma
What 2 structures does the RAS act on to produce wakefulness? What happens if 1 vs both are destroyed?
1) Basal forebrain and cholinergic cells
2) Midbrain structure with raphe nucleus with serotonin
One destroyed: learn simple tasks still
Both destroyed: no learning/intelligent behavior
What is the basal forebrain responsible for regarding sleep/wake?
being awake/alert but being still; if activity blocked then NREM EEG
What is the midbrain structure with the raphe nucleus responsible for regarding sleep/wake?
being alert/awake with movement
What is the peribrachial area and what is it responsible for in sleep?
cholinergic nucleus in the brainstem that has a role in REM Sleep behaviors and projects to the medial Pontine
What is the medial pontine reticular formation and what happens if you remove it?
a nucleus on the pons that results in no REM if you lesion it and induces REM if you inject cholinergic
What happens if you lesion the subcoerulear nucleus?
loss of atonia in REM
What is insomnia and what can it cause?
disorder of slow wave sleep resulting in prolonged inability to sleep; anxiety and depression
What is Narcolepsy and what can cause it?
falling asleep in times you shouldn’t; sleep apnea
What are 3 disorders of REM sleep?
1) Sleep paralysis (during sleep)
2) Cataplexy (REM randomly while awake)
3) REM sleep behavioral disorder (act out dreams)
What type of cells if destroyed can lead to narcolepsy or cataplexy?
orexin cells
What is damaged in REM sleep behavioral disorder a large proportion of the time? What population is this common in?
subcoerulear; older population
What are the 3 NT that act in concordance with waking?
1) Cholinergic: alert no movement
2) Serotenergic: alert with movement
3) Orexin: maintaining waking
What are the 3 measures of sleep?
1) Electroencephalogram (EEG): brain waves
2) Electrooculogram (EOG): eye movement
3) Electromyogram (EMG): muscle movement
What stages are light sleep and what are slow wave sleep?
1-2 = light sleep and 3-4 = slow-wave sleep
What sleep stage do sleep spindles and K complexes occur? What are they?
stage 2 (N2) or light sleep; sleep spindles are 12-14hz oscillations; k complexes big spike in oscillation
What does a typical sleep cycle look like?
N1 –> N2 –> N3 –> N2 –> REM
What happens to zeitgebers during jet lag?
they are accelerated or decelerated
Why is sleep regulation said to be a two process system that is self-regulating?
it is both homeostatic and circadian (larger gap between sleep drive and drive for arousal more likely to sleep)
What happens to neurons in the forebrain during sleep?
more and longer hyperpolarization
What are the 3 main brain regions involved in sleep?
1) SCN - circadian system
2) Hypothalamus, basal forebrain (sleep promoting) vs other areas of hypothalamus (arousal) - homeostatic system
3) Pontine nuclei - ultradian system for REM vs nREM
Damage to the posterior hypothalamus (encephalitis lethargica) causes?
continuous sleep
Damage to the anterior hypothalamus causes?
sleep difficulties
What does the preoptic area of the hypothalamus do?
induces sleep by inhibiting arousal mechanisms in the body
What happens in the brainstem when REM-on?
1) Cholinergic nuclei active
2) sublaterodorsal nucleus active
What happens in the brainstem when REM-off?
1) noradrenergic locus coeruleus
2) serotonergic raphe nuclei
3) ventral PAG area
What chemicals are arousal inducing?
Orexin, Histamine, AcH, NE, Glutamate
What chemicals are sleep inducing?
Adeonsine, GABA etc.
What NT are involved in nREM/REM cycling?
ACh, Gluta, Sero, NorAdren, GABA`
What do hypnotic drugs do?
Depress the CNS; GABAergic agonists (benzos)
What do anti-hypnotic drugs do? (3)
stimulate the CNS; promote waking; boost activity of catecholamines
What are is the chronobiotic substance and what does it do?
melatonin (from pineal); timing properties, controlled by SCN, increase with darkness
