The stimulus control of biting in Aplysia

A number of different parameters of the biting response of Aplysia californica were examined while varying either the strength of excitatory stimuli that elicit biting, or the strength of inhibitory stimuli that suppress biting and produce satiation. Response amplitude, response latency and the interresponse interval of repetitive responses were the parameters investigated. In individual animals as well as in the mean data, all parameters of the biting response were found to be affected in a graded manner when the concentration of seaweed extract was varied, and when animals were fed to different levels of satiation. Feeding animals with non-nutritive bulk produced graded effects similar to those seen when animals were fed with seaweed. These results indicate that the biting response is modulated in a graded manner by external stimuli which elicit the response, as well as by internal stimuli which produce satiation.