Frontiers in Bioscience-Scholar (FBS) is published by IMR Press from Volume 13 Issue 1 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
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Cephalopods are endowed with the most sophisticated nervous system among invertebrates and exhibit a repertoire of complex behaviors, such as spatial and observational learning. Cephalopod eyes supply a wide range of information which are utilized for these learning behaviors. Although our understanding of vertebrate physiology greatly benefited from the sub-cellular analysis of cephalopod nervous system, as shown by the discovery of the ionic bases of action potentials and of the Ca2+ requirement for neurotransmitter release Surprisingly, the cellular basis by which the visual system drives the sophisticated repertoire of cephalopod behaviors are still poorly understood. In this review, we will describe the current knowledge about cephalopod phototransduction. Light excites cephalopod photoreceptors by either inducing Ca2+ release from intracellular stores or activating cation-permeable channels by an as yet unknown mechanism. A 92 kDa protein, which is homologous to the Drosophila transient receptor potential (TRP) gene, is the most likely mediator of light-induced currents in cephalopods. A number of models which explain the mechanism whereby cephalopod TRP channel is gated by light will be discussed.