title: Photopic transduction implicated in human circadian entrainment.
abstract: Despite the preeminence of light as the synchronizer of the circadian timing system, the phototransductive machinery in mammals which transmits photic information from the retina to the hypothalamic circadian pacemaker remains largely undefined. To determine the class of photopigments which this phototransductive system uses, we exposed a group (n = 7) of human subjects to red light below the sensitivity threshold of a scotopic (i.e. rhodopsin/rod-based) system, yet of sufficient strength to activate a photopic (i.e. cone-based) system. Exposure to this light stimulus was sufficient to reset significantly the human circadian pacemaker, indicating that the cone pigments which mediate color vision can also mediate circadian vision.
authors.affiliation: Program in Neuroscience, Harvard Medical School, Department of Medicine, Brigham and Women's Hospital, Boston, MA 02115, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Zeitzer
authors.forename: R E
authors.initials: RE
authors.lastname: Kronauer
authors.forename: C A
authors.initials: CA
authors.lastname: Czeisler
mesh_terms: D000293:Adolescent; D000328:Adult; D001831:Body Temperature / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D006801:Humans; D008297:Male; D008550:Melatonin / Q000097:blood; D010775:Photic Stimulation; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*
chemical_list: D008550:Melatonin