This study exemplifies the ability of animal models to establish causality by recreating a specific mutation observed in humans and establishing that it is sufficient to alter gene expression and behavior. While the mechanism by which this SNP impacts risk for substance abuse is not known, the modulation of morphine-induced locomotor activation and ethanol-induced dopamine release suggests that it may modulate sensitivity to the reinforcing effects of drugs. The focus by Ramchandani et al. (2011) on measures of dopamine release in both mice and humans provides circumvents the need to identify equivalent behavioral measures in both mice and humans.
