ENTRAINMENT OF THE CIRCADIAN SYSTEM OF MAMMALS BY NONPHOTIC CUES

Although light is the principal zeitgeber to the mammalian circadian s ystem, other cues can be shown to have a potent resetting effect on th e clock of both adult and perinatal mammals. Nonphotic entrainment may have both biological and therapeutic significance. This review focuse s on the effect of behavioral arousal as a nonphotic cue and the neuro chemical circuitry that mediates arousal-induced entrainment in the ad ult rodent. In addition, it considers the role of nonphotic entrainmen t of the developing circadian system in perinatal life prior to the es tablishment of retinal input to the clock.