Striatal Effective Connectivity to Predict Treatment Response in Cocaine Misuse

Inclusion Criteria: * Male and female subjects * Age 18 to 50 * Meet current DSM-IV criteria for cocaine dependence who are seeking treatment. Exclusion Criteria: 1. Current DSM-IV diagnosis of any psychoactive substance dependence other than cocaine, marijuana, nicotine, or alcohol 2. Have a DSM-IV axis I psychiatric disorder or neurological disease or disorder requiring ongoing treatment and/or making study participation unsafe 3. Significant current suicidal or homicidal ideation 4. Medical conditions contraindicating levodopa/carbidopa or pharmacotherapy (e.g., evidence of any movement disorder, clinically significant pulmonary disease, cardiovascular disease, liver or kidney disease, seizure disorder) 5. Taking CNS active concomitant medications 6. Taking medications known to have significant drug interactions with the study medication (e.g., CYP P-450-2D6 inhibitors, such as tamoxifen, iron salts, pyridoxine, monoamine oxidase inhibitors, phenothiazines, selegiline, anesthetics) 7. Having conditions of probation or parole requiring reports of drug use to officers of the court 8. Impending incarceration 9. Pregnant or breast feeding for female patients 10. Inability to read, write, or speak English 11. Having plans to leave the immediate geographical area within 3 months 12. Unwillingness or not competent to sign a written informed consent form 13. Individuals who have pacemakers, metal or electromechanical implants or metallic foreign bodies 14. Patients who are known to be HIV positive will not be included due to possible CNS effects of HIV. 15. Alcohol withdrawal symptoms or history of significant previous alcohol withdrawal symptoms