biological rhythms and sleep Flashcards
biological rhythms
inherent rhythm that controls or initiates various biological processes
period
time required to complete a cycle of activity
circannual rhythm
Yearly (e.g., migratory cycles of birds)
infradian rhythm
Less than a year (e.g. human menstrual cycle)
circadian rhythm
Daily (e.g. human sleep-wake cycle)
ultradian rhythm
Less than a day (e.g. eating cycle)
endogenous rhythms
Control is within the animal, not stimulus-driven (i.e. exogenous)
Neural system that times behaviour
Allows animals to anticipate events (ex: sunrise) before they happen
free-running rhythms
Remove all external cues: no changes in light, no food schedule, no clocks, no alarms, no phone, etc
nocturnal animals
those that are chiefly awake at night (rodents)
If left in constant darkness: awake-sleep period is <24 hours
If left in constant light: awake-sleep period is >24 hours
diurnal animals
those that are mostly awake during the day, sleep at night
If left in constant darkness: awake-sleep period is >24 hours
If left in constant light: awake-sleep period is <24 hours
entrainment
determination or modification of the period of a biorhythm
Our biological clock is entrained by light
Blind individuals and sailors serving on submarines may experience sleep problems
Zeitgeber “time giver”
environmental event that entrains biological rhythms
Light resets the biological clock; social interactions (yawning)
shift work
drastic changes in work schedule (ex: working morning shift to working graveyard shift) is more stressful than subtle changes (evening shift to graveyard shift)
jet lag
changing time zones: eastward travel- Lose time, difficult to adjust
Westward travel- gain time, easier to adjust
Suprachiasmatic Nucleus
Chief pacemaker of circadian rhythms
Located just above (“supra”, dorsal to) the optic chiasm, in the hypothalamus
retinopothalamic pathway
Originate from set of photoreceptors in the retina, called cryptochromes
Melanopsin- photopigment
Provides light information to the SCN
Entrains the rhythmic activity of the SCN
why does the oscillator oscillate
Is the endogenous rhythm of the SCN a result of nature (genetic factors) or nurture (learned)?
In absence of Zeitgebers, there is still rhythmiccity to an animals behaviour
An animals behaviour will remain rhythmic even if previous generations are not exposed to Zeitgebers
If the SCN is lesioned in a mother rat, so that her own behaviour lacks rhymicity her (normal) offspring will still demonstrate biological rhythms
beta rhythm
Fast brain-wave activity (15 to 30 Hz) pattern associated with a waking EEG
theta rhythm
Large brain waves (4 to 7Hz) associated with drowsiness (stage 1)
alpha rhythm
Large, extremely regular brain waves (7 to 11 Hz) associated with relaxation/drowsiness
delta rhytm
Slow brain-wave activity (1 to 3Hz) pattern associated with deep sleep (also known as slow wave sleep
REM sleep
Fast brain-wave pattern displayed by the neocortical EEG record during sleep;
stages of sleep
Stage 1: low voltage, fast activity
Stage 2: K complexes and sleep spindles
SWS- Stage 3/ Stage 4: delta waves
Emergent stage 1 EEG: REM or paridoxal sleep
90 minute cycles
Non-REM
Body movements (toss and turn), decline in body temperature, heart rate decreases, blood flow increases
Some dreaming, but different (less vivid) from REM
Sleepwalking, sleeptalking, and night terrors happen in NREM
REM
Eye movements dart around rapidly (in other stages, eyes roll slowly)
Atonia- seen in the EMG: absence of muscle tone due to the inhibition of motor neurons
Sleep paralysis
Dreams are quite vivid
Stickgold and the Tetris experiment
freud
dreams symbolize unfulfilled and unconsious wishes
Manifest content: bizarre events in the dream
Latent content: “true” meaning of the dream
jung
personal and collective unconsious
Common themes in dreams reflect the “collective unconsious” (history of the human species)
How do we empirically determine which is right?
J ALLan hobson
Dreams are personal, but they have no meaning
The cortex, receiving signals from the brainstem, generates random images from memory stores
