Long-lasting electrical changes of identified Hermissenda neurons, the type B photoreceptors, can account for concomitant associative behavioral changes. Depolarization of the type B cells after paired light and rotation accumulates (as monitored with intracellular electrodes) with reptition. This accumulation was specific to stimulus pairing (versus light alone or explicitly unpaired stimuli) and to the orientation of the nervous system with respect to the center of rotation; it provides a neural step in the acquisition of associative behavioral changes for gastropod mollusks and possibly other species.