Sign-tracking is a form of autoshaping where animals develop conditioned responding directed toward stimuli predictive of an outcome even though the outcome is not contingent on the animal's behavior. Sign-tracking behaviors are thought to arise out of the attribution of incentive salience (i.e., motivational value) to reward-predictive cues. It…

Three experiments with rat subjects examined resurgence of an extinguished instrumental response using the procedure introduced by Epstein (1983) with pigeons. There were three phases: (1) initial acquisition of pressing on a lever (L1) for pellet reward, (2) extinction of L1, and (3) a test session in which a second lever (L2) was inserted,…

Changes in reward magnitude or value have been reported to produce effects on timing behavior, which have been attributed to changes in the speed of an internal pacemaker in some instances and to attentional factors in other cases. The present experiments therefore aimed to clarify the effects of reward magnitude on timing processes. In Experiment…

The ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) may provide modulatory signals that, respectively, influence hippocampal (HPC)- and striatal-dependent memory. Electrophysiological studies investigating neural correlates of learning and memory of dopamine (DA) neurons during classical conditioning tasks have found DA…

In appetitive Pavlovian learning, animals learn to associate discrete cues or environmental contexts with rewarding outcomes, and these cues and/or contexts can potentiate an ongoing instrumental response for reward. Although anatomical substrates underlying cued and contextual learning have been proposed, it remains unknown whether specific…

The cAMP-dependent protein kinase (PKA) is known to play a critical role in both transcription-independent short-term or intermediate-term memory and transcription-dependent long-term memory (LTM). Although distinct phases of LTM already have been demonstrated in some systems, it is not known whether these phases require distinct temporal patterns…

Rats in a Pavlovian situation were trained under three different reward schedules, at either a 30 s or a 90 s intertrial interval (ITI): Consistent reward (C), 50% irregular reward (I), and single alternation of reward and nonrewarded trials (SA). Activity was recorded to the conditioned stimulus (CS) and in all 10 s bins in each ITI except the…

Combined activation of dopamine D1- and NMDA-glutamate receptors in the nucleus accumbens has been strongly implicated in instrumental learning, the process in which an individual learns that a specific action has a wanted outcome. To assess dopaminergic activity, we presented rats with two sessions (30 trials each) of a one-lever appetitive…

Feeding behavior of Aplysia provides an excellent model system for analyzing and comparing mechanisms underlying appetitive classical conditioning and reward operant conditioning. Behavioral protocols have been developed for both forms of associative learning, both of which increase the occurrence of biting following training. Because the neural…