NONASSOCIATIVE AND ASSOCIATIVE MODIFICATION OF HEAD-WAVING PRODUCED BY AVERSIVE TENTACULAR STIMULI IN APLYSIA

Head-waving, a spontaneously occurring exploratory and appetitive beha vior of the marine mollusc Aplysia, provides an opportunity to examine mechanisms of learning expressed in a nonreflexive behavior. The pres ent study explores nonassociative and associative forms of learned, mo dification of head-waving produced using an aversive stimulus as reinf orcement. Experiments on intact, freely behaving animals demonstrate t hat training with electric shock as an aversive unconditioned stimulus , delivered unilaterally to the anterior tentacles, produces a learned shift in head-waving behavior away from the side on which shock was a pplied. This behavioral change is a novel learned behavioral response that is influenced by the topographic location of an aversive stimulus . Furthermore, training with application of tentacle shock reinforceme nt, contingent upon the animal's head position, produces operant condi tioning of head-waving. Thus, anterior tentacle shock is effective as an aversive reinforcer for both nonassociative and operant learning ex pressed in the head-waving behavior of Aplysia.