Appetitive-aversive interactions in Pavlovian fear conditioning.

The existence of value coding and salience coding neurons in the mammalian brain, including in habenula and ventral tegmental area, has sparked considerable interest in the interactions that occur between Pavlovian appetitive and aversive conditioning. Here we studied these appetitive-aversive interactions at the behavioral level by assessing the learning that occurs when a Pavlovian appetitive conditioned stimulus (conditional stimulus, CS) serves as a CS for shock in Pavlovian fear conditioning. A Pavlovian appetitive CS was retarded in the rate at which it could be transformed into a fear CS (counterconditioning), but the presence of the appetitive CS augmented fear learning to a concurrently presented neutral CS (superconditioning). Retardation of fear learning was not alleviated by manipulations designed to restore the associability of the appetitive CS before fear conditioning but was alleviated by manipulations designed to increase the aversive quality of the shock unconditioned stimulus (US). These findings are consistent with opponent interactions between the appetitive and aversive motivational systems and provide a behavioral approach for assessing the neural correlates of these appetitive-aversive interactions.