Efferent optic nerve fibers mediate circadian rhythms in the Limulus eye

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Science  01 Jul 1977:
Vol. 197, Issue 4298, pp. 86-89
DOI: 10.1126/science.867057


When the horseshoe crab is kept in constant darkness, the lateral eye produces larger electroretinographic and optic nerve responses at night than during the day. These circadian rhythms are mediated by synchronous bursts of efferent impulses in the optic nerve trunk. The endogenous efferent activity appears to increase both the gain and the quantum catch of the photoreceptors.