Stanley J. Weiss - US grants

Behavior can be brought under the discriminative control of events in an organism's environment through discrimination training. When reinforcement is delivered independently of an organism's behavior in the presence of a particular stimulus, discriminative control is acquired by the conditioned stimulus (CS+) over the conditioned response (CR) through a classical conditioning operation. In comparison, operant discriminative control occurs when responses emitted in the presence of the positive stimulus (S+) are followed by reinforcement and responses emitted in the presence of the negative stimulus (S-) are never followed by reinforcement. Following intradimensional operant discrimination training in which S+ and S- are on the same stimulus continum, a generalization test (where many different values on the continuum are presented) often reveals that maximum responding is not controlled by S+. Rather, the gradient's peak is displaced from S+ in a direction away from S-. This phenomenon - peak-shift - has not been reported following classical intradimensional discrimination training. The proposed research will compare pigeon keypeck generalization gradients after key-pecking is established in one group by operant (response-reinforcer) and in another by classical (stimulus- reinforcer) intradimensional training procedures. Strategies are described to match training parameters over groups, varying only the presence or absence of a response-reinforcer contingency. Several independent assays will be administered to determine the contingency controlling keypecking. If the classically conditioned group produces peak-shift, this will be the first clear demonstration of this theoretically important generalization phenomenon with a respondent. If they do not produce peak-shift, while the matched operant controls do, we will have strong evidence that operant and classical discriminative processes may differ. Types of future systematic parametric investigations that might better define these potential differences are discussed.

There are many biological constraints on learning and the associability of various events. For example, when a tone-plus-light compound is food related, light is selectively attended to, but the tone gains considerable control when the compound is associated with shock. It has not been recognized that in these studies reporting stimulus-reinforcer interactions, food and shock were confounded with schedule component preference, since food is a preferred condition, and shock nonpreferred. A pilot study measured selective associations for the first time in a paradigm designed to unconfound preference and class-of-reinforcer. Component preferences were generated solely with differential positive reinforcement. The interaction profile generated in that experiment was like those produced when selective associations to shock and to food related compounds were compared. The proposed research program is based on the assumption that many of what up to now have been classified as stimulus-reinforcer interactions might be special instances of a stimulus-preference interaction, with the latter interactions subsuming the former. The proposed research would systematically test this hypothesis parametrically, with different species, and in situations where differential preferences are generated solely with negative reinforcement contingencies. The stimulus-preference interaction model parsimoniously relates these selective associations to fundamental psychological processes responsible for choice behavior and conditioned preference.

DESCRIPTION (provided by applicant): Drug-related stimuli can elicit drug craving in drug abusers and have been implicated in relapse. An important objective of drug abuse treatment is to reduce or eliminate the control that these cues have over individuals. The goal of the research proposed here is to use an animal model to develop procedures that can be used to effectively treat drug cues. Specifically, we will investigate techniques for temporarily restoring or amplifying the expectation-outcome error signal produced by non-reinforcement as a means of enhancing extinction and conditioned inhibition of drug seeking. The first aim of the proposed research is to develop a way to deepen the extinction of drug cues by using combinations of drug- as well as non-drug- related stimuli to increase the error signal generated during extinction learning. A second aim is to create similar procedures that deepen the conditioned inhibition of drug seeking. A third aim is to deepen the extinction of drug cues by pharmacologically-reinstating the effects of a previously extinguished drug cue prior to exposing that cue to additional, extensive extinction. Achieving these aims could (1) provide insight into ways of enhancing the extinction and conditioned inhibition of drug seeking via behavioral and pharmacological interventions, and (2) form the empirical basis for the creation of an effective extinction- based treatment for drug abuse, a major public health problem. PUBLIC HEALTH RELEVANCE: The proposed research will investigate methods for reducing and ultimately eliminating the power that drug-associated stimuli have over drug users. Such stimuli have been shown to produce drug craving and have been implicated in relapse. Therefore, this research could lead to the development of effective treatments for drug abuse, a major public health problem.