Three experiments used rats to investigate the role of dopamine activity in learning to inhibit conditioned fear responses (freezing) in extinction. In Experiment 1, rats systemically injected with the D2 dopamine antagonist, haloperidol, froze more across multiple extinction sessions and on a drug-free retention test than control rats. In Experiment 2, rats extinguished under an intracerebrove...

Women exhibit more rapid escalation from casual drug taking to addiction, exhibit a greater withdrawal response with abstinence, and tend to exhibit greater vulnerability than men in terms of treatment outcome. In rodents, short-term estradiol intake in female rats enhances acquisition and escalation of drug taking, motivation for drugs of abuse, and relapse-like behaviors. There is also a sex ...

JONATHAN SUGAM: Phasic nucleus accumbens dopamine encodes risk-based decision making behavior (Under the direction of Regina M. Carelli) When deciding to act organisms must correctly evaluate the costs and benefits of action selection in order to optimize resources. Several factors influence the evaluation of reward value including the behavioral cost, the delay to, probability of, and magnitud...

Behavioral sensitization of psychostimulant-induced locomotor activity in rats has been proposed as a model of addiction and is accompanied by neuroadaptations in the nucleus accumbens and related circuits. Here, we used in vivo intracellular recordings to examine electrophysiological properties of accumbens neurons from animals that did or did not exhibit behavioral sensitization after repeate...