title: Electrophysiological evidence for circadian rhythmicity in a mammalian pineal organ.
abstract: Long-term electrophysiological recordings from the guinea-pig pineal organ show that three types of intrinsic cells can be distinguished: (i) Cells showing constant firing rates over periods of up to 24 hours. (ii) Cells which are highly active during the day and show a low firing rate during the night. (iii) Cells which exhibit low activity during the day and enhanced activity during the night; these cells can be strongly inhibited by 1 min of light given during the night. Both the light- and darkness-activated cells show activity patterns which closely follow season-dependent differences in day- and night-lengths. In addition, both cell types show an oscillatory pattern in maintained activity.
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D003624:Darkness; D006168:Guinea Pigs; D008027:Light; D008297:Male; D009474:Neurons / Q000502:physiology; D010870:Pineal Gland / Q000502:physiology*