Biophysical processes in invertebrate photoreceptors: recent progress and a critical overview based on Limulus photoreceptors

Abstract

Photoreceptor cells are special neurons which convert light to an electrical signal. The absorption of a photon by a rhodopsin molecule triggers a sequence of chemical processes leading to a change in the membrane voltage of the photoreceptor. The mechanism of this light-induced voltage change is different in vertebrates and invertebrates. Light causes a hyperpolarization in vertebrates, but a depolarization in invertebrate photoreceptors.