Membrane-potential-sensitive dyes for optical monitoring of activity in Aplysia neurons.

Two membrane-associated dyes (WW375 and NK2367) which change their absorption of light when the membrane potential changes have been studied using several preparations form Aplysia. Action potentials are easily observed in nerve trunks (from a number of axons), in bag cell clusters, in some of the larger single cells of the parietovisceral ganglion, and in the optic nerve. Physiological effects of the dyes on the circadian rhythm of activity in the eye are described.