Pilot Study of Repetitive Transcranial Magnetic Stimulation in Cocaine Craving

Background: \- Cocaine addiction is often difficult to treat, particularly because exposure to others using cocaine or to pictures of cocaine may evoke cocaine craving and lead a person to resume cocaine use after having quit. Breaking this link with cocaine craving might improve treatment for cocaine addiction. Research suggests that repetitive pulses of transcranial magnetic stimulation (rTMS) applied to the skull can change nerve cell firing in the brain. rTMS was recently approved as a treatment for depression, and is being studied as a way to reduce drug craving. However, because only a few small studies have looked at the effects of rTMS on cocaine craving, more research is needed on whether it is effective in reducing cocaine craving and use in individuals who currently use cocaine on a regular basis. Objectives: \- To determine whether transcranial magnetic stimulation can lower craving for cocaine when given in connection with cocaine-related images. Eligibility: \- Individuals at least 18 years of age who have used cocaine for at least 2 years and currently using at least 3 times per week. Design: * This study involves an initial screening visit, two brain imaging sessions, five rTMS sessions, and two follow-up visits. * Participants will be screened with a medical history, physical examination, urine samples, questions about drug use history and previous efforts to quit, and tests for breath alcohol and nicotine levels. * Participants will have two magnetic resonance imaging (MRI) scan sessions: one baseline scanning session before starting their rTMS sessions and a second scanning session after their last rTMS session . Part of each scanning session involves functional MRI (fMRI) scans. During the fMRI scans, participants will look at pictures related to cocaine use and pictures that are not related to cocaine use. Participants will also perform a simple decision task during the scans. * Participants will have five rTMS sessions, one per day for 5