Phototransduction by retinal ganglion cells that set the circadian clock.
Light synchronizes mammalian circadian rhythms with environmental time by modulating retinal input to the circadian pacemaker-the suprachiasmatic nucleus (SCN) of the hypothalamus. Such photic entrainment requires neither rods nor cones, the only known retinal photoreceptors. Here, we show that retinal ganglion cells innervating the SCN are intrinsically photosensitive. Unlike other ganglion cells, they depolarized in response to light even when all synaptic input from rods and cones was blocked. The sensitivity, spectral tuning, and slow kinetics of this light response matched those of the photic entrainment mechanism, suggesting that these ganglion cells may be the primary photoreceptors for this system.
Berson
David M
DM
Department of Neuroscience, Brown University, Providence, RI, 02912 USA. David_Berson@brown.edu
Dunn
Felice A
FA
Takao
Motoharu
M
D000818:Animals; D001369:Axons / Q000648:ultrastructure; D001683:Biological Clocks; D002940:Circadian Rhythm; D003712:Dendrites / Q000648:ultrastructure; D007546:Isoquinolines; D007700:Kinetics; D008027:Light; D055537:Light Signal Transduction; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012165:Retinal Ganglion Cells / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D017299:Rod Opsins / Q000032:analysis / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000502:physiology*; D000099210:Melanopsin
D007546:Isoquinolines; D017299:Rod Opsins; D000099210:Melanopsin; C017475:lucifer yellow