Epidemiological studies have shown repeatedly that one of the best prognosticators of adolescent or young adult drug use is whether an individual’s peers use drugs. The high concordance rates of drug use within peer groups can be explained by either selection theories or social learning theories. Selection theories propose that individuals choose or select their peers based on shared attitudes and behaviors regarding drug use. On the other hand, social learning theories propose that individuals learn drug use behaviors (or abstinent-related behaviors) by observing and imitating the behavior of their peers. Experimental studies addressing these theories have been limited because of a lack of preclinical models that allow laboratory animals to observe and mimic the drug use of others. To circumvent this problem, Dr. Mark Smith and his colleagues constructed custom-built, ‘social learning’, drug-administration chambers that enabled two animals to intravenously self-administer drugs at the same time and in the same chamber. Thus, these chambers allowed these animals to observe (and mimic) one another’s behavior. A wire screen prevented one rat from accessing the intravenous line and response lever of its partner. In order to determine the impact of observing a peer self-administer cocaine on the acquisition of cocaine use, Dr. Smith and colleagues assessed the behavior of three groups of rats. The first two groups were pair-housed and the third group was reared in isolation. For the first pair-housed group, one rat from each pair was trained to self-administer cocaine in isolation prior to reintroduction to its partner in the ‘social learning’ operant chamber where both rats had access to cocaine. For the second pair-housed group, neither had cocaine self-administration experience, and one rat from each pair did not have access to cocaine when placed in the ‘social learning’ operant chamber. The rats reared in isolation self-administered cocaine in standard (non-social-learning) test chambers. Dr. Smith and his colleagues found acquisition of cocaine self-administration was fastest among rats partnered with peers that had cocaine-self-administration experience, whereas rats partnered with peers that were not self-administering cocaine were the slowest to acquire cocaine self-administration. These findings demonstrate that observing a peer using cocaine has a profound impact on the development of drug use, whereas exposure to an abstinent peer is protective in delaying drug self-administration. As such, these findings provide evidence to support social learning theories underlying the development of drug use. The use of an animal model was an essential feature to this study that allowed the investigators to determine the cause-and-effect role that social contact with drug-using and abstinent peers have on the acquisition of drug use. These types of questions cannot be directly addressed in human populations, thus emphasizing the importance of animal models of human behavior in biomedical research. Dr. Smith has been a member of CPDD since 1994. He currently serves on the Board of Directors and as Chair of the Animals in Research Committee. He previously served as Chair of the Awards Committee (2013-2017). Dr. Cooper has been a member of CPDD since 2013. She is a member-elect of the Board of Directors and currently serves as a member on the Animals in Research Committee. She has previously served on the Program Committee (2014-2017) and Nominating Committee (2016-2017). By Ziva Cooper, Ph.D., Animals in Research Committee Member
