title: Light, behavior, and biologic rhythms.
abstract: The most potent environmental synchronizer of "biologic clocks" in mammals is the light-dark cycle. The author describes experiments that identify a particular pathway--a derect connection between retina and hypothalamus--as the main route by which such biologic rhythms as the daily activity cycle, the estrous cycle, and the annual reproductive cycle are entrained to the external environment.
mesh_terms: D000818:Animals; D001519:Behavior / Q000502:physiology*; D001683:Biological Clocks; D002940:Circadian Rhythm; D006224:Cricetinae; D004971:Estrus; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D008027:Light; D008297:Male; D011247:Pregnancy; D051381:Rats; D012098:Reproduction; D012621:Seasons; D013495:Supraoptic Nucleus / Q000502:physiology; D013737:Testis / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception
chemical_list: D007987:Gonadotropin-Releasing Hormone