Reward Processing in Cocaine Addiction

Background: \- Cocaine affects the brain's ability to process information. However, different people respond to cocaine in different ways, and differences in brain structure and function may affect how cocaine alters brain activity. By using functional magnetic resonance imaging (fMRI) to monitor brain activity during tasks that provide simple rewards, researchers hope to better understand how the brain responds to rewards and how this response is affected by drugs like cocaine. Objectives:

• To determine the effect of cocaine administration on the reward experience in cocaine-dependent individuals.
• To study genetic and personality factors that may contribute to cocaine dependence. Eligibility: \- Individuals between 18 and 45 years of age who either are cocaine-dependent and not seeking treatment or are healthy volunteers. Design:
• Participants will be asked to avoid consuming alcohol and restrict consumption of caffeine prior to the study. Participants provide urine and breath samples to be tested for chemicals that may interfere with the study.
• All participants will complete a training session and at least one fMRI scanning session. During the training session, participants will be introduced to the reward tasks and MRI equipment.
• Healthy volunteers will have a single fMRI session that will involve reward tasks to be completed during the scanning. Rewards will include small amounts of fruit juice and the opportunity to win money.
• Cocaine-dependent participants will have a training session and three experimental sessions including 1) a mock MRI scan to test cocaine tolerance, 2) one fMRI scan with reward tasks after administration of IV cocaine, and 3) one fMRI scan with reward tasks after administration of IV placebo (saline solution). Rewards will include small amounts of fruit juice and the opportunity to win money.
• In addition to the scans, participants will provide a blood sample for further study and will answer questionnaires provided by the researchers.