The proposed research will determine how conditioned incentive functions established with traditional reinforcers (e.g., food) compare to those produced when behavior is maintained by drug self-administration. These findings would be directly relevant to recent proposals that the study of """"""""drug craving"""""""" be approached from an incentive-motivational framework. The independent variable will be the proportion of drug reinforcers earned in tone and in light components of the training schedule relative to the proportion earned in the absence of these stimuli. The dependent variable will be the very sensitive stimulus compounding assay that reveals the influence of excitatory and inhibitory conditioned incentive properties established to discriminative stimuli. The former properties energize behavior and the latter depress it. Initially, cocaine will be used to establish stimulus control because it is an efficacious reinforcer that produces minimal physical dependence. Other studies would determine the incentive-motive function for drugs that produce physical dependence (e.g., heroin) as well as the nature (appetitive or aversive) of the motivational mechanisms controlling various types of drug-reinforced behavior. Preliminary studies report, for the first time, (1) rats' responding for cocaine under a three-component multiple schedule, and (2) increased drug seeking and intake produced by compounding discriminative stimuli controlling self-administration. These findings support the feasibility of the proposed research program while revealing its potential for providing insights into the mechanisms responsible for the remarkable persistence of drug-seeking behavior in humans. When the program is completed, we should have (1) attained a much better understanding of the role of conditioned incentive mechanisms in the maintenance of behavior by drugs of abuse, (2) compared conditioned incentive functions developed with conventional reinforcers and drugs, (3) developed an assay to compare incentive-motive functions for different drugs that maintain behavior, (4) determined whether selective associations occur for drug reinforcers and how they are related to the incentive-motive process, (5) determined how drug maintained behavior is related to traditional appetitive and evasive reinforcement mechanisms, (6) incorporated drug-maintained behavior under general-process learning theory and contingency analysis by making connections with the major theoretical model of motivation in animal learning, and (7) provided new insights into potential drug abuse treatment strategies through behavioral manipulations.
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