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What is a circadian rhythm?
a pattern of behavioural, biochemical, or physiological fluctuation that has a 24 hour period
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What does it mean to be Diurnal?
active during the day (e.g. humans, and other primates).
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What does it mean to be nocturnal?
active at night (e.g. rodents, hamsters)
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What is a free running animal?
a rhythm of behaviour shown by an animal deprived of external cues about time of day.
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What is a period?
the interval of time between two similar points of successive cycles such as sunset to sunset.
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What is a phase shift?
a shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus
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what is entrainment?
the process of synchronizing a biological rhythm to an environmental stimulus.
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what is a zeitgeber?
time giver. A stimulus (light-dark cycle) that entrains circadian rhythms.
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What is the suprachiasmatic nucleus (SCN)?
a small region of the hypothalamus above the optic chiasm that is the location of a circadian oscillator
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What is a pineal gland?
a secretory gland in the brain midline; the source of melatonin release
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what is the retinohypothalamic pathway?
the projection of retinal ganglion cells to the SCN
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what is melanopsin?
a photopigment found within particular retinal ganglion cells that project to the SCN
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What is a dimer?
a complex of two proteins that have bound together
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what is an ultradian?
a rhythmic biological event whose period is shorter than that of a circadian rhythm, usually from several minutes to several hours long.
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What is a circannual?
occuring on a roughly annual basis
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what is an infradian?
referring to a rhythmic biological event whose period is longer than that of a circadian rhythm-longer than a day
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what is electroencephalography?
the recording and study of gross electrical activity of the brain recorded from large electrodes placed on the scalp.
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what is electro-oculography (EOG)?
the electrical recording of eye movements
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What is electromyography (EMG)?
the electrical recording of muscles
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What is slow wave sleep? (SWS)
sleep divided into stages 1-4 that is defined by the presence of slow wave EEG activity.
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What is rapid eye movement (REM) sleep?
a stage of sleep categorized by small amplitude, fast EEG waves, no postural tension, and rapid eye movements.
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What is a desynchronized EEG? (beta activity)
a pattern of EEG activity comprising a mix of many different high frequencies with low amplitude.
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What is an alpha rhythm?
a brain potential of 8 to 12 Hz that occurs during relaxed wakefulness
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What is a vertex spike?
a sharp wave EEG pattern that is seen during stage 1 SWS
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What is stage 1 sleep?
the initial stage of SWS. Consists of small EEG waves of irreg frequency, slow heart rate and reduced muscle tension
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What is stage 2 sleep?
a stage of SWS. Bursts of regular 14-18 Hz EEG waves called sleep spindles.
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What is a sleep spindle?
a characteristic of a wave in the EEG of a person in stage 2 of SWS
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What is the K complex?
a sharp negative EEG potential that is seen in stage 2 sleep
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What is stage 3 sleep?
a stage of SWS defined by spindles mixed with larger amp waves
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whats a delta wave?
the slowest type of EEG wave, characteristic of stages 3 and 4 SWS
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What is stage 4 sleep?
a stage of SWS defined by the presence of delta waves at least half the time.
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