Operant conditioning of head waving in Aplysia.

Head waving is a naturally occurring behavior that Aplysia use to explore their environment. Aplysia can be operantly trained to modify their head-waving response, increasing the amount of head waving on one side of their body in order to terminate the presentation of an aversive strong light. Acquisition of the operant response is rapid, within 10 min. Two observations indicate that the operant conditioning is under the control of the contingencies of reinforcement: (i) contingent reinforcement significantly elevates operant responding, reversing the contingencies significantly reduces operant performance, and reinstating the contingencies significantly reinstates operant responding; and (ii) yoked controls do not acquire the operant response, yet these same animals readily learn when reinforcement is made contingent upon their responses. Finally, internally derived cues (e.g., proprioceptive or reafferent) appear to play a predominant role in acquiring the operant response. Since progress has been made in understanding the cellular basis of classical conditioning in Aplysia, this demonstration of operant conditioning in a response system that is well-suited for a cellular analysis provides a preparation in which it is possible both to analyze the cellular mechanisms of operant conditioning and to address the theoretical question of the relationship between classical and operant conditioning on a mechanistic level.