Behavioral and dopaminergic factors associated with risky decision-making in rats: Implications for substance abuse

Excessive risky decision-making is common in multiple psychiatric disorders, including substance abuse disorder. The risky decision-making task (RDT) models addiction-relevant risk-taking in rats by measuring preference between a small reward and large reward associated with systematically increasing risk of shock. This thesis examined the relationship between risk-taking in the RDT and multiple cognitive and neurobiological addiction-relevant phenotypes. Risk-taking was associated with elevated impulsive action, but not impulsive choice or habit formation. Furthermore, risk-taking predicted locomotor sensitivity to first-time nicotine exposure and resilience to nicotine-evoked anxiety. Finally, risk-taking was associated with elevated phasic dopamine release and sensitivity to the dopamine transporter inhibitor nomifensine in the nucleus accumbens. Collectively, these data demonstrate that risk preference in the RDT predicts a cluster of traits associated with substance abuse, and may have utility for identification of neurobiological and genetic biomarkers that engender addiction vulnerability