Regulation of mammalian circadian behavior by non-rod, non-cone, ocular photoreceptors

Melanie S. Freedman, Robert J. Lucas, Bobby Soni, Malcolm von Schantz, Marta Muñoz, Zoë David-Gray, Russell G. Foster*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

672 Citations (Scopus)


Circadian rhythms of mammals are entrained by light to follow the daily solar cycle (photoentrainment). To determine whether retinal rods and cones are required for this response, the effects of light on the regulation of circadian wheel-running behavior were examined in mice lacking these photoreceptors. Mice without cones (cl) or without both rods and cones (rdta/cl) showed unattenuated phase-shifting responses to light. Removal of the eyes abolishes this behavior. Thus, neither rods nor cones are required for photoentrainment, and the murine eye contains additional photoreceptors that regulate the circadian clock.

Original languageEnglish
Pages (from-to)502-504
Number of pages3
Issue number5413
Publication statusPublished - 16 Apr 1999


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