Chronic cocaine causes age-dependent increases in risky choice in both males and females.

Individuals who use cocaine exhibit maladaptive decision-making, overweighting rewards, and underweighting potential risks. We previously showed that chronic cocaine self-administration in young adult male rats causes long-lasting increases in risk taking. The present study expanded upon these findings to determine whether effects of cocaine on risk taking depend on the route of cocaine administration and extend to females.

MeCP2 Expression in a Rat Model of Risky Decision Making.

Many neuropsychiatric disorders are associated with abnormal decision making involving risk of punishment, but the underlying molecular basis remains poorly understood. Methyl CpG-binding protein 2 (MeCP2) is an epigenetic factor that regulates transcription by directly binding to methylated DNA. Here, we evaluated MeCP2 expression in the context of risk-taking behaviors using the Risky Decision-making Task (RDT), in which rats make discrete choices between a small "safe" food reward and a large "risky" food reward accompanied by varying probabilities of punishment.

Effects of nucleus accumbens amphetamine administration on performance in a delay discounting task.

Chronic administration of cocaine can cause pronounced and enduring cognitive alterations such as increases in impulsive choice. Chronic cocaine can also result in enhanced dopamine (DA) release in the nucleus accumbens (NAc) in response to reward-related cues. It is possible that this enhanced DA release in the NAc is a mechanism by which cocaine increases impulsive choice.

Food consumption and weight gain after cessation of chronic amphetamine administration.

Cessation of drug use often coincides with increased food consumption and weight gain in recovering addicts. However, it is not known whether this phenomenon (particularly the weight gain) is uniquely human, or whether it represents a consequence of drug cessation common across species. To address this issue, rats (n = 10/group) were given systemic injections of D-amphetamine (3 mg/kg) or an equal volume of saline vehicle for 9 consecutive days.

Affective and cognitive mechanisms of risky decision making.

The ability to make advantageous decisions under circumstances in which there is a risk of adverse consequences is an important component of adaptive behavior; however, extremes in risk taking (either high or low) can be maladaptive and are characteristic of a number of neuropsychiatric disorders. To better understand the contributions of various affective and cognitive factors to risky decision making, cohorts of male Long-Evans rats were trained in a "Risky Decision making Task" (RDT), in which they made discrete trial choices between a small, "safe" food reward and a large, "risky" food reward accompanied by varying probabilities of footshock. Experiment 1 evaluated the relative contributions of the affective stimuli (i.