This study never started, no funding.

Our proposal will enable us to study cocaine patients to determine whether varenicline can weaken brain arousal to drug cues in an fMRI imaging setting, which is what we theorize. This supplement supports a pilot imaging study in cocaine dependence. It will evaluate the impact of varenicline on the brain response to ultra-brief drug and comparison cues in an event-related fMRI paradigm. This is a pilot study.

We will additionally examine the impact of varenicline on addiction-relevant behavioral probes of impulsivity, inhibition, attentional and affective bias. The proposed study will provide the first brain-behavioral probes of varenicline's cocaine-relevant actions in humans, and will provide the critical scientific rationale to move the agent into future collaborative clinical trials.

Inclusion Criteria:

• Physically healthy male substance abuse subjects age 18-55.

Exclusion Criteria:

• 1) Participation in clinical trial and receipt of investigational drug(s) during previous 60 days 2) Clinically significant cardiovascular, hematologic, hepatic, renal, neurological or endocrinological abnormalities 3) History of serious head trauma or injury causing loss of consciousness that lasted more than 3 minutes. 4) Presence of magnetically active prosthetics, plates, pins, broken needles, permanent retainer, bullets, etc. in subject's body (unless a radiologist confirms that its presence is unproblematic). A x-ray may be obtained to determine eligibility. 5) Claustrophobia or other medical condition disabling subject from lying in the MRI for approximately 60 minute