Cocaine Induced Place Preference in a Virtual Environment

Exposure to drug cues has been shown to induce cravings and precede relapse in substance abusers. This extends from the specific implements of drug administration to the context and environment in which the drug is used. These learned associations are problematic for the treatment for drug addiction, as it is exceedingly difficult to avoid all places, people and objects that dominated one's life prior to recovery. The proposed method by which these cues elicit cravings is through classical conditioning. This conditioning has been experimentally manipulated in rodents in a paradigm known as conditioned place preference (CPP), in which an animal can be conditioned to prefer a specific environment through repeated pairings of a rewarding substance to that environment. We have created a virtual analogue of the CPP paradigm to explore the contributions of contextual conditioning to substance abuse in humans. In this study, four non-treatment seeking cocaine abusers have been given repeated pairings of cocaine in one specific virtual environment, and a placebo in a different virtual environment. Before and after the pairings, the subjects were allowed unrestricted access to both environments without the influence of cocaine. Following the pairings, participants spent an increased percentage of time in the cocaine-paired environment as well as rated the cocaine paired room as $\sim 42{\%}$ more preferable than the placebo paired room. Subjective ratings of drug effects and mood were also collected using a visual analogue scale throughout the experiment. This work is the first report of an experimentally induced CPP in humans, and this paradigm could be used to test the efficacy of treatments aimed at reducing the effect of these conditioned cues on substance abuse.