The conditioned rewarding effects of novelty compete with those of cocaine

In humans, individuals particularly attracted to sensation and novelty seeking may have an increased vulnerability to abuse drugs. In rodents, behavioral and neurochemical evidence show that the processes mediating novelty reward and drug reward overlap. Therefore, access to novelty might provide an alternative learning history that has potential to compete with conditioned drug reward. The purpose of this dissertation, therefore, was to test this hypothesis in rats using a place conditioning procedure with cocaine and novelty. Briefly, rats were initially conditioned with cocaine to prefer one side of an unbiased place conditioning apparatus. In the subsequent phase, half of the rats had repeated access to a novel object on their initially unpaired (no-drug) side. Both groups were then tested on separate days for preference in a drug-free state and in the cocaine-drug state. One objective of this dissertation was to aid understanding of the complex interaction between novelty reward and drug reward. This goal was met by the findings that conditioned novelty reward competed with cocaine reward in a manner that was sensitive to cocaine dose, drug-state, and retention intervals. More so, competition by novelty was more likely to occur with lower cocaine doses, shorter retention intervals, and without unpaired exposure to the environmental cues