test 1 Flashcards
how is deep sleep assessed?
how difficult it is to wake someone, the degree of EEG or behavioural responses to external stimuli, degree of drowsiness that follows waking,
Which features of REM sleep are categorized as tonic?
postural muscle paralysis, low-voltage cortical EEG, loss of temperature control
Which features of REM sleep are categorized as phasic?
rapid eye movements, peripheral muscle twitches
The major contributors to mammalian EEG recordings are postsynaptic potential occurring in large ______________ neurons with somata located in layer ____ of the 6-layered cortex.
pyramidal, 5
Looking at your phone at night results in the ________________ (suppression / production) of melatonin. This results in a phase _______________ (advance / delay) of your circadian rhythm.
suppression, delay (confirm?)
what was thought of sleep historically?
that is was a state of quiet that resulted from the withdrawal of arousing input to the cortex
what did early scientists studying sleep believe?
that sleep resulted from a global reduction in neural activity or blood flow
when were our ideas of sleep revolutionized?
throughout the 19th and 20th centuries due to research
what did Ishimori, Legendre, and Pieron do?
deprived dogs of sleep, took brian extracts or CSF from these dogs and injected them into control dogs
what did Ishimori, Legendre, and Pieron find?
recipient dogs became sleepy when injected with fluids from sleep deprived dogs
recipient dogs did not become sleepy when injected with fluids from dogs that were not sleep deprived
Ishimori, Legendre, and Pieron overall findings?
there must be a chemical agent in the brain that promotes sleep, builds up during the day
what are EEGs?
electoencephalogram
what do EEGs show?
electrical activity in the brain changed throughout the cycle of waking and sleeo
what is sleep characterized by EEG?
high-amplitude, slow waves and burst of faster activity (sleep spindles)
what do EEGs show during waking?
low-amplitude, faster waves
what did Alfred Loomis do?
in 1930s made EEG recordings of people while awake and asleep
what did Loomis note from EEG study?
people transitioned through different stages of sleep, A-E, characterized by different EEG patterns
what did Loomis note about two specific sleep stages?
hard to wake people from stages D and E (deep sleep)
why is influenza relevant?
influenza viral pandemic (1918)
killed approximatley 40 million
many people who survived developed encephalitis lethargica
what did constantin von economo do?
studied the brain after death
where was insomnia localized?
posterior part of hypothalamus
where was somnolence localized?
anterior part of hypothelamus
what is there new evidence of?
that specific regions of the brain may trigger or suppress sleeo
what did frederic bremer do?
experimentally transected brainstems of cats
what happens with a lower medulla transection?
most cranial nerves still reach the brain, continued alternating cycles of electrical activity that resembled periods of wake/sleep
what happens with a midbrain transection?
cats brains could not receive input from most of the cranial nerves (sensory systems)
EEG patterns resembled those of sleep and did not regain signs of waking
what did early research on sleep seem to support? (Bremer)
the idea that cessation of sensory input to the brain results in sleep
what did magoun, moruzzi and lindsley do?
research on cats
what did magoun, moruzzi and lindsley find?
electrical stimulation of the reticular formation (specifically ARAS) triggered sustained cortical activation regardless of whether primary sensory pathways were intact or interrupted
where is the reticular formation?
brainstem
what does it mean if the reticular formation is damaged?
sensory stimulation would cause transient cortical arousal during the stimulation, but not sustained arousal
what is ARAS necessary for?
sensory stimuli to produce sustained activation of the cortex and stimulation of the ARAS alone was sufficient to produce cortical arousal, even if primary sensory projections to the cortex were absent
what does ARAS mediate?
mediates arousal to external stimuli because it is innervated by collateral fibres branching off from principle pathways that carry specific sensory info to the thalamus
who discovered REM sleep?
Kleitman and aserinsky
what did Kleitman and aserinsky do?
recorded electrical activity of eye muscles using electrodes attached to skin lateral to the eyes
how did Kleitman and aserinsky record eye movement?
electrooculogram (EOG)
what did Kleitman and aserinsky find during sleep?
slow, rolling eye movements stopped shortly after sleep onset
what are REMs?
bursts of rapid, jerky, bilaterally symmetrical eye movements
what is REM associated with?
lightening of sleep, increased breathing and heart rates
what sleep periods resemble waking?
periods with high numbers of REMs accompanied by cortical EEG patterns with rapid, low-amplitude activity
how often does REM ocur?
every 2 hours or less, three or four times during the night
what did william dement study?
humans and cats
what did dement find?
soon after falling asleep people descended from wakefulness through a series of progressively deeper non-REM (NREM) sleep stages with the first REM sleep period occurring an hour or more after sleep onset
alternating REM and NREM sleep periods in cycles just over…
90 minutes
how much does REM sleep occupy?
occupied ~20-25% of night’s sleep with longer REM sleep episodes later in the night
what did michael jouvet study?
cats
what did jouvet find?
called REM sleep paradoxical sleep because of discrepancy between EEG pattern and behaviour of cat
what did jouvet find during PS?
there was complete, sustained loss of postural muscle tone - atonia
what did jouvet attribute loss of postural muscle tone to?
descending inhibition of spinal motor systems by a region of the pons
consistent features of REM sleep?
- EEG recordings during REM sleep resembled pattern seem in awake, aroused organisms more than NREM stages of sleep
- threshold for arousal during REM sleep quite high, inconsistent with EEG pattern reflecting very light sleep or arousal
- NREM and REM sleep alternated rhythmically throughout the sleep phase
- self-reported mental activity changed with NREM and REM sleep (eg. dreams)
what did the first reports of daily rhythm involve?
the sleep movements of plants:
prayer plant and sensitive plant
what did jean-jacques d’ortous de mairin do?
placed a sensitive plant in a dark closet without access to light, noted that leaves continued to move up and down in synchrony with external day-night cycle
what did augustin pytamus de candolle do?
kept plant in constant light, daily leaf movements continued rhythmically but on a cycle of roughly 22 hours. over time the leaves’ rhythm fell out of synch with the (unseen) external cycle of day and night
what did blinded rats show about circadian rhythms?
showed robust activity rhythms in absence of external time cues, not synchronized to day-night cycle
what did fruit flies show about circadian rhythms?
rhythms persisted under constant environmental conditions
what did maynard johnson find?
period of the activity rhythms in white-footed mice changed systematically in response to changes in the intensity of the constant lighting to which they were exposed
what did johnson hint at?
hinted at a mechanism by which sleep-wake cycles can become linked to the day night cycle
who termed the coin circadian?
franz halberg
what does circadian mean?
circa = about
dian = day
what are circadian rhythms?
rhythms that express periods near 24h in length in the absence of external time cues
what are electrophysiological recordings of sleeo?
EEG, EOG, EMG
heart rate, oxygen saturation of blood, air flow through nostrils, respiratory effort, leg movements
what is the polysomnogram (PSG)?
combo of EEG, EOG, EMG and other physiological measures
what is the electroencephalogram?
EEG record is generated by amplifying and recording minute electrical signals that are the produce of activity of neurons within the brain
how does EEG placement work?
electrodes are placed on the scalp in standardized placement system
10/20 system
what are EEG changes highly correlated with?
state of sleep and waking
what do EEG recordings not look like simple sine waves?
a single electrode on the surface of the scalp is recording many neurons - often (eg. when awake) some neurons are being excited, and others are being inhibited
what kind of electrical pattern are EEGs?
desynchronized
what happens for electrical pattern to be synchronized?
when the majority of the population of neurons under an electrode are excited or inhibited at the same time, the resulting electrical pattern is synchronized
what is fourier analysis?
any complex waveform can be decomposed into a series of pure sine waves of different frequencies that are weighted differently, depending on how strongly each frequency is represented in that waveform
what do fourier analysis yield?
a power spectrum
what is a power spectrum?
plots how much power (Weighting) is associated with each pure sine wave frequency that contributes to a given waveform
highest peak = most powerful frequency
what are fourier analysis and resulting power spectrums (of EEGs) used to do?
characterize the stages of sleep
how are stages of sleep characterized?
by which EEG frequencies dominate them
what are the frequencies relevant for studying sleep?
beta, alpha, theta, delta, slow oscillations
beta waves?
> 12 Hz
alpha waves?
8-12 Hz
theta waves?
4-8 Hz
delta waves?
1-4 Hz, slow waves, voltage amplitude 75-140 µV
slow oscillations?
<1 Hz, very high amplitudes > 140 µVQW
what did Rauf et al (2013 focus on?
six paranormal beliefs and their associations with sleep quality variables, as well as isolated sleep paralysis and exploding head syndrome
where did rauf get their questions from?
four paranormal beliefs were evaluated using a sub-scale from the paranormal assesment scale, two developed by authors
response options ranged from 1 (definitely not) to 5 (definitely yes)
what is sleep efficiency?
the ratio between sleep duration and the total time dedicated to sleep in bed expressed as a percentage
how did rauf measure sleep efficiency?
using three items from pittsburg sleep quality index
how did rauf measure insomnia symptoms?
measured using items from the insomnia severity index - 1 to 5
how did rauf assess EHS and ISP?
using 11 items each adapted from the EHS interview and fearful isolated sleep interview
rauf participants?
8853 participants, classifed as 93% white, 67% female, mean age of 47 years
rauf overarching results?
people with trouble sleeping seem to believe more in paranormal activity
rauf: sleep efficiency results?
Most people with good sleep efficiency are saying they definitely do not believe in paranormal beliefs; people with poor sleep efficiency are more likely to believe in paranormal activity
rauf: sleep latency results?
People with low sleep latency (good) saying they definitely do not believe in these things and vice versa
rauf: sleep duration results?
People with longer sleep duration are less likely to believe in paranormal activities and vice versa
rauf: insomnia results?
Higher insomnia = more severe, people with less insomnia are less likely to believe in paranormal activities and vice versa
rauf: paralysis results
Belief that aliens have visited earth, of the participants that said yes experienced EHS more, same with sleep paralysis
Belief about life after death, paralysis higher with definitely yes
transition to sleep stage?
fully awake, engaged with environment or relaxed, eyes closed
transition to sleep characteristics - fully awake?
low-amplitude, desychronized EEG pattern (dominated by high frequencies in beta range, some alpha)
EOG recordings related to voluntary eye movement
EMG shows high muscle tone
transition to sleep characteristics - relaxed, eyes closed?
EEG shows more alpha waves
NREM stage 1 (N1) sleep: EEG?
slowing EEG patterns, loss of alpha waves and decreasing beta power
lower voltage, mixed frequency pattern
increase theta and delta waves
NREM stage 1 (N1) sleep: EMG?
EMG shows stable, low activity
NREM stage 1 (N1) sleep: physiological findings?
respiration and heart rate slow, lose awareness of surroundings
weak external stimuli can cause return to wakefulness, sometimes denial of having been asleep
how long is NREM stage 1 usually?
usually a brief transition stage
what is NREM stage 2 (N2) sleep?
first true sleep stage, EEG shows mixed frequencies (Slower than N1), onset is marked by first appearance of sleep spindles and K complexes
what are sleep spindles? (N2)
period bursts of EEG activity, 0.5 to 1.5 seconds
12-16Hz with gradual increase in amplitude followed by decrease in amplitude
what are the frequency of slow spindles?
12-14 Hz
what are the frequency of fast spindles?
14-16 Hz
what are K complexes?
last longer than 0.5 seconds, rate of 1-3 per minute
where are K complexes commonly from?
frontal cortical regions
what are K complexes (amplitude wise)
high amplitude, negative half wave (down state) followed by slow positive half wave (up state)
when do K complexes appear?
spontaneously or with sensory stimulation during sleep
what is NREM stage 3 (N3) sleep?
further slowing of breathing and heart rate, low EMG activity, no significant EOG activity, slowing of EEG
what did N3 sleep historically include?
stages 3 and 4 of NREM sleep
what happens in N3 sleep?
appearance of high-amplitude delta waves, also referred to as slow wave sleep
what were stages 3 and 4 previously categorized on?
the proportion of EEG recording that was delta wave, with N3 = 20-50% delta waves and N4 = >50% in 30 second duration
what is N3 defined as now?
at least 20% delta waves in a scoring epoch
what is REM sleep?
emerges out of N2 sleep, EEG amplitude is low with mixed frequencies
what does REM EEG show?
low amplitude with mixed frequencies, theta and alpha waves - EEG difficult to distinguish from N1 sleep
what do REM animal studies reveal?
prominent, regular theta-frequency rhythms in hippocampus
ponto-geniculo-occipital (PGO) spikes: large amplitude waveforms occurring sequentially in the pons, lateral geniculate nucleus and occipital cortex
what is onset of REM sleep signaled by?
loss of muscle tone (atonia) - illustrated by flattening of EMG
what does REM EOG show?
busts of rapid eye movements - conjugate movements
what happens physiologically in REM sleep?
body temperature regulation is disabled, rapid or irregular breathing and heart rate, changes in blood pressure (sexual arousal)
bursts of motor activity in small peripheral muscles while postural muscles are paralyzed
what do studies reveal about REM sleep - dreaming?
~80% of awakenings from REM sleep are accompanied by reports of dreaming
often with bizarre/irrational narrative, strong (often negative) emotional content
examples of defining characteristics of sleep in other stages?
- sleep spindles are present but harder to detect in N3
- delta-frequency EEG activity can show up briefly in waking and sleep stages other than N3 (micro-sleeps)
- very brief, EEG-defined waking (micro-arousals) can occur during all sleep stages
are boundaries between sleep stages absolute?
no
sleep distribution throughout the night?
affected by numerous factors, “normal” sleep pattern is idealized, healthy, young adults with consistent sleep schedule
what is a hypnogram?
record of a sleep period
how long does NREM-REM cycle average?
90-110 mins
what does N2 sleep occupy?
most of a nights total sleep duration ~ 45-55%
what does N3 sleep comprise?
~13-23% and is concentrated in the first half
REM sleep occupies?
~20-25% and is concentrated in the second half
how many REM cycles do people typically pass through?
4-6 NREM/REM cycles, typically wake out of a REM cycle
issues related to lab sleep studies?
standardized conditions are essential to diagnose intrinsic sleep disorders, people must be isolated from any potential external sources of sleep disturbances, allows for the effects of experimental manipualtions to be attributed only to those manipulations
what is the first night effect?
disrupted sleep experience by many people during their first night of trying to sleep in an unfamiliar setting
what does first-night effect ential?
- longer latencies to enter deeper sleep stages
- persistence of alpha activity later into the sleep phase
- signed of increased vigilance and reduced SWS in the brain
What is the adaptation night?
initial night in the sleep study environment to familiarize participants with the environment before data collection
other issues with sleep lab studies?
sleep problems experienced at home may not occur in the lab
what are accurate measures of sleep studies at home?
compact, portable computers, sleep recording devices, portable EEG-recording systems
what are issues with at home sleep measurement?
absence of sleep technologist
lack of complete physiological monitoring
uncontrolled conditions in the home
what is an actigraphy?
small electronic device (an actigraph) worn on non-dominant wrist measures activity patterns using accelerometers, sensitive to movement
what can actigraphys measure?
can measure sleep onset, sleep end, total sleep duration, degree of sleep disruption
what are actigraphys not useful for?
measuring sleep stages or disorders
what can vary actigraphy results?
validity of analysis may vary with age, medical condition and treatment (eg. children and ADHD)
each different brand of actigraphy and associated softward needs to be validated against PSG to determine accuracy
what are actigraphys not particularly accurate at?
detecting wake during the sleep period
what is the multiple sleep latency test (MSLT)?
participants undergo a PSG study overnight
tested 4-5 next day at 2h intervals to measure latency to fall asleep
in quiet/dark room for 20 minutes while PSG recorded
what does latency to fall asleep suggest?
reflects the degree of sleep drive - very short latencies considered sign of excess sleepiness caused by inefficient prior sleep or a sleep disorder
what is typical adult latency to sleep onset? (MSLT)
10-20 minutes
what are latencies of < 5 minutes?
associated with excessive daytime sleepiness and cognitive performance deficits
what are latencies of 5-9 minutes?
ambiguous
what is sleep latency affected by?
age, time of day
what is the maintenance of wakefulness test?
measures how long people can resist falling asleep in a sleep compatible environment over four trials
what are circadian rhythms?
endogenously (internally) generated cycles of behaviour and physiology that express periods in constant conditions (in the absence of external cues) near 24 hours
what are free-running rhythms?
refer to the circadian rhythm displayed by an individual when in constant external conditions
most free running rhythms do not have…
near 24-hour periodicity
expressing physiological and behavioural rhythms appropriately timed to day-night cycle has two requirements?
internal generation of an ~24 h rhythm
synchronization of that rhythm to an external cycle
what is entrainment?
synchronization of that rhythm to an external cycle - control of the period and phase of an endogenously generated rhythm by an external cycle
what is period control?
when the free-running (non-24h) period (length) of the internal clock is changed in the presence of an external cycle to match the period (length) of the external cycle
what is phase control?
when the circadian rhythm adopts and maintains stable timing in relation to the external cycle (eg. awakening daily at a consistent phase of the lighting cycle), even when the external cycle is shifted
what is zeitgeber?
environmental variables that are capable of acting as circadian time cues – eg. sun and moon
what does the light switch do?
light controls the body clock by activating the suprachiasmatic nucleus (SCN)
what do melanopsin receptors in the eye respond to?
the presence of light by transmitting signals to the SCN
what happens in the light?
melanopsin receptors transmit signals, no melatonin released
what happens in the dark?
melanopsin receptors transmit signals, melatonin is released
what have studies shown with free-running rhythms?
free-running rhythms in the blind can be entrained by having individuals consume melatonin before bed
what did Hack et al find?
that administration of 0.5mg of exogenous melatonin entrained the free-running rhythms of most blind subjects
entrainment is NOT…
just synchrony between two rhythms
for an external cycle to be a zietgeber…
it must be demonstrated that the free running rhythm of an organism does not simply have a period identical to that of the external cycle
how to demonstrate that an external cycle is a zietgeber?
you must shift the external cycle and observe whether there is a corresponding phase shift in the organisms rhythm
how might you test if an external lighting cycle is entraining an animal in a lab setting?
shift the lighting cycle by several hours, if the animal’s stable phase relation to the lighting cycle was coincidental, changing the lighting cycle should have no effect on the rhythm
what happens if changing a lighting cycle is consistently followed by a shift in animal’s entrained rhyths?
they re-establish their previous phase relation to the lighting cycle - daylight is a zeitgeber
what effects circadian rhythms?
brief light pulses affect circadian rhythms depending on the phase of the free-running rhythm at which an animal is exposed to the light pulses
what is a phase shift?
phase shift in your circadian rhythm means that your bedtime and wake-up time will move earlier in the day (phase advance) or later in the day (phase delay)
what is phase advance shift?
shortening of the period for at least one cycle because your bedtime and wake-up time shift to earlier in the day
what is phase delay shift?
lengthening of the period for at least one cycle because your bedtime and wake-up time shift to later in the day
what does light exposure in the morning do?
advances your rhythm (shifts it earlier), whereas light qexposure in the evenings delays it
what are divisions in behaviour and physiology referred to as?
subjective day and subjective night
subjective day/night for diurnal species?
subjective day is when individual is awake and active
subjective day/night for nocturnal species?
subjective day is when they are asleep
what happens to light early on in the activity cycle of a nocturnal species?
light early on in their cycle has the opposite effect it would on a person
what is a phase response curve?
plot of the size and direction of phase shifts produced by brief light pulses against the circadian/subjective time at which the light pulses were given
what is a dead zone?
falls during the subjective day; a phase during which the circadian clock is relatively unaffected by the stimulus
what is early subjective night?
phase during which the stimulus causes phase delays
what is late subjective night?
phase during which the stimulus causes phase advances
is there variation in internal clocks between people?
yes
what does entrainment do?
each internally generated circadian rhythm adopts a 24 h period and establishes a unique position (phase relation) relative to the zeitgeber cycle (typically light-dark)
what is a phase lead?
some clocks will be naturally short free-running rhythms, become stably entrained at an early phase relative to the external cycel
what is phase lag?
other clocks will have naturally longer free-running rhythms, become entrained at a later phase of the zeitgeber cycle
early birds?
go to bed early and rise early = phase lead = naturally short circadian rhythm relative to zeitgeber
night owls?
stay up late and sleep late = phase lag = naturally longer circadian rhythm relative to zeitgeber
how to determine phase (lead or lag)?
we use behavioural or physiological processes (eg. activity, body temp) driven by internal clocks to determine its phase
what are masking effects?
external events that affect behaviour or physiological directly (independent of internal clock)
what is positive masking?
environmental change that provokes behaviour at an inappropriate circaidna phase
what is negative phase?
environmental change that prevents behaviour that would normally occur at that time
what do masking effects complicate?
the study of internal clocks. is a behaviour synchronized to an external cycle or actually entrained to that cycle?
what did Nielsen et al do?
administered the typical dreams questionnaire to 1248 university students, attrition = 1181 participants, 70% female, mean age = 19
most prevalent themes in nielson dream study?
being chased or pursued but not physically injured, sexual experiences
who were chasing dreams most common for?
women
who were sex dreams most common for?
men
what did women have higher dream prevalence rates for?
abortion, failing exam, someone dead, school
what did men have higher dream prevalence rates for?
travelling to another planet, aliens, UFOs, killing someone, sexq
most common dreams for 19-60 year olds?
sexual experiences, person now dead as alive`
most common dreams for 16-18 year olds?
failing an exam, insects or spiders, floods, combo of attack/pursuit
nielson average number of dreams recalled?
about 1 in every 3 days
neilson average number of recalled nightmares?
1 in almost every 2 weeks
gender effect for nightmares?
women recalled more nightmares per month than men
dicussion of dreams?
chase/pursuit might be evolutionarily adaptive dream to practice escaping predators
falling/flying might be prevalent of sliency, involvement of motor imagery and therefore more memorable
frankl et al study?
surveyed 19000 individuals and assess dream recall frequency
how was dream recall frequency quantified?
high DRF = >/= 3 nights per week
low DRF = < 3 nights per week
DRF frequency: pandemic?
DRF was higher during pandemic than before
what were some of the variables associated with high DRF?
female gender and nightmares
Mackey and decicco findings?
dreams have been shown to be reflective of waking day events, health related worries yielded more health-related dreams than waking day illness did
what are poor emotional well-being and depression associated with?
distinct dream imagery, including more sadness, anger and aggression imagery
what did mackay and decicco aim?
aimed to determine whether living through a pandemic is associated with changed dream imagery
mackey and decicco procedure?
19 uni students,
participants were given a dream journal and asked to record their dreams in as much detail as possible
what topics of dreams went up during covid?
head, food, location change, total virus
armitage study?
purpose was to evaluate the effect of self-related stress levels on dream recall and gender
armitage participants?
15 undergrad, 10 female, all in early twenties
armitage procedure?
subjects participated during last month of course work prior to exams, completed dream diaries daily for one month
armitage average dream recall?
39 for males, 43 for females
armitage average stress level?
1.48
armitage results?
men recorded more low stress dreams, women recorded more high stress dreams
freud relation to dreaming?
published interpreation of dreams in 1900
freud interpreation of dreams?
drams represented the discharge of hidden instinctual desires, form of wish fulfilment
bizarre content of dreams expressed instinctual drives (often sexual) in a safe manner
what did freud think about dreams?
random images, emotions not random
reduced mental capacity during sleep allows supressed thoughts to emerge
wegner 2004?
people who were told to actively supress thoughts about a particular perosn were more lkely to dream about them
freud, dreams operate on…
two levels of consciousness
manifest level?
the dream we consciously recall after waking up (surface level)
latent level?
the deeper, unconscious level, where the true meaning of a dream lies
what did freud use…
psychoanalytics to uncover the latent meaning of client’s dreams to help resolve hidden conflicts
common symbolism according to freudian dream analysis?
phallic symbols (guns/snakes), vaginal symbols (doors/windows), sexual acts (climbing/descending)
what is social stimulation theory?
defines dreaming as a world-simulation that is likely to have, or have had, an adaptive function during human evolutionary history
what is control-master theory?
dreams reflect the person’s efforts to adapt to reality
- dreams represent out unconscious attempts to find solutions to emotionally relevant problems
what is continuity hypothesis?
content of dreams is related to events during waking life
- content is often familiar, progression of events is not
side effect theory?
dreams are a side effect of brain activity during sleep
- neurons in visual, motor, memory and emotion areas become active
- minimal thought during sleep tries to make sense of/connect hallucinations
