Examination of relationships between response topography and the development of behavioral tolerance to effects of cocaine with rats and pigeons

Tolerance is the attenuation of drug effects after repeated administration. The phenomenon of tolerance is multifaceted and closely related to the problems of substance abuse and substance dependence. The development of tolerance to behavioral effects is dependent on physiological and behavioral factors. A need for behavioral mechanisms to account for tolerance is illustrated through the Before-After Test of Tolerance. In this test two groups are subjected to the same experimental contingencies and drugs, however, the Before group receives the drug prior to experimental contingencies and the After group receives the drug following the contingencies. Typically, only the Before group develops tolerance, and this outcome shows that tolerance is contingent on a learning history while under the influence of drug. The finding, known as contingent tolerance, has been replicated using a variety of drugs, experimental arrangements, and animal species. Interestingly, contingent tolerance has not been exhibited in pigeons. This species difference may be a result of using species-typical responses to test for tolerance. In contrast, similar studies using rats and non-human primates included species-arbitrary responses, and contingent tolerance has been the typical result.;This dissertation addresses the role of response topography in the development of tolerance to the rate-decreasing effects of cocaine with two experiments using the Before-After Test of Tolerance. Experiment 1 required rats to use species-typical licking responses in a procedure similar to that previously had resulted in tolerance for both Before and After groups of pigeons. Experiment 2 employed pigeons and a species-arbitrary treadle-pressing response, an arrangement similar to those that have led to contingent tolerance when rats were used. Experiment 1 resulted in tolerance for both the Before and After groups, which is consistent with the idea that response topography may influence the development of tolerance. Experiment 2 resulted in tolerance for both the Before and After groups, which is inconsistent with the idea that response-topography was the confounding variable in development of contingent tolerance. The outcome, however, was consistent with previous pigeon experiments. It was therefore concluded that factors other than the operantly maintained response topography must be influencing the species differences in development of tolerance to effects of cocaine.