Functional Magnetic Resonance Imaging (fMRI) Studies in Pathological Gambling (PG) and Obsessive-Compulsive Disorder (OCD)

Inclusion Criteria: * Male or female adults diagnosed with pathological gambling or obsessive compulsive disorder aged 18-55. * Subject has signed an informed consent form * Must provide contact information * Must be in generally good health * Must be willing and able to read written instructions and complete scales * Must be English speaking * In the opinion of the investigator, the subject is capable of complying with all study procedures Pathological Gamblers only: * Current diagnosis of pathological gambling, supported by DSM-IV SCI-PG * Must score ≥ 5 on SOGS * Must score ≥ 2 on item number 1 on the G-SAS * Subjects must have a severity score of ≥ 4 (moderately ill) on the Clinical Global Impressions Scale - Severity (CGI-S) * Must score ≥ 10 on questions 1-5 on PG-Y-BOCS * Must score ≤ 15 on YMRS * Must have gambled once within past 2 weeks of Screening Visit. Exclusion Criteria: * Subjects with a primary diagnosis of schizophrenia, personality disorder, or other psychotic disorders * Subjects with a primary diagnosis of an Axis I disorder that may require intervention * Must not score \>24 on the Montgomery-Asberg Depression Rating Scale (MADRS) (pathological gamblers only) * Subjects who live in a restrictive environment * Subjects with a current DSM-IV diagnosis of substance dependence or abuse, excluding nicotine * Subjects reporting a history of drug and/or alcohol dependence or abuse; subjects who report occasional drug use in the past will be discussed by a panel (consisting of Dr. Gilbert, Dr. Fan and Dr. Bartz), and will be considered for participation on a case by case basis * Subjects who have used psychotropic medications in the past week to six weeks (depending on the medication) * Subject has a positive drug urine screen * Female subjects who are pregnant * Subjects who report a history of severe liver, heart, or kidney disease because these conditions are associated with neurological sequella * Employees of the investigator or study center or their families * Finally, subjects who do not satisfy the following criteria will be excluded because they will be unable to undergo the MRI procedure. Specifically, subjects will be excluded who have: 1. a pacemaker 2. any implanted metallic chips in their head 3. ever worked around a metal lathe or had a shrapnel (war or gun shot) wound/injury 4. an implanted neuro-stimulatory or infusion/insulin pump 5. any devices placed in their blood vessels 6. any metal in/on their body 7. kidney disease 8. sickle-cell or hemolytic anemia 9. claustrophobia 10. any metallic tattoos 11. any body piercing that cannot be removed 12. dental braces 13. any permanent make-up 14. any cardiac stints