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Functional absence of extraocular photoreception in hamster circadian rhythm entrainment
1Department of Physiology, Leiden University Medical Centre, University of Leiden, P.O. Box 9604, 2300 RC, Leiden, Netherlands. j.h.meijer@physiology.medfac.leidenuniv.nl
Brain Research
|July 21, 1999
Abstract:
The mammalian circadian pacemaker is entrainable by light via the retina. The putative role of extraocular light perception was investigated in blinded hamsters. These animals were shaved and exposed to a light-emitting pad for either 30 min or 3 h. The absence of any phase-shifting effects on wheel running activity rhythms indicates that extraocular light perception plays no functional role in photic entrainment of the circadian pacemaker in the hamster.