14 - Biological Rhythms, Sleep, and Dreaming Flashcards
Diurnal
Active during the light periods of the daily cycle
Circadian rhythm
A pattern of behavioral, biochemical, or physiological fluctuation that has a 24-hour period
Nocturnal
Active during the dark periods of the daily cycle
Free-running
Referring to rhythm of behavior shown by an animal deprived of external cues about time of day
Period
The interval of time between two similar points of successive cycles, such as sunset to sunset
Phase shift
A shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus
Entrainment
The process of synchronizing a biological rhythm to an environmental stimulus
Zeitgeber
Literally “time-giver.” The stimulus (usually the light-dark cycle) that entrains circadian rhythms.
Suprachiasmatic nucleus (SCN)
A small region of the hypothalamus above the optic chiasm that is the location of a circadian oscillator
Pineal gland
A secretory gland in the brain midline; the source of melatonin release
Retinohypothalamic pathway
The projection of retinal ganglion cells to the suprachiasmatic nuclei
Melanopsin
A photopigment found within particular retinal ganglion cells that project to the suprachiasmatic nucleus
Dimer
A complex of two proteins that have bound together
Ultradian
Referring to a rhythmic biological event whose period is shorter than that of a circadian rhythm, usually from several minutes to several hours long.
Circannual
Occurring on a roughly annual basis
Infradian
Referring to a rhythmic biological event whose period is longer than that of a circadian rhythm-that is, longer than a day
Electroencephalography (EEG)
The recording and study of gross electrical activity of the brain recorded from large electrodes placed on the scalp
Electro-oculography (EOG)
The electrical recording of eye movements
Electromyography (EMG)
The electrical recording of muscle activity
Slow-wave sleep (SWS)
Sleep, divided into stages 1-4, that is defined by the presence of slow-wave EEG activity
Rapid-eye-movement (REM) sleep
Also called paradoxical sleep. A stage of sleep characterized by small-amplitude, fast-EEG waves, no postural tension, and rapid eye movements.
Desynchronized EEG
Also called beta activity. A pattern of EEG activity comprising a mix of many different high frequencies with low amplitude