Brain Mechanisms of Human Motivation

The study involves five sessions. In the first session, participants will play a computer
task. In the second session, participants will go through a clinical interview and will have
an EEG recording while playing another computer task. In the third session, participants will
undergo an fMRI scan while playing another computer task. All tasks assess reward learning.
At three and six months after the final session, participants will come back for a follow-up
interview session during which a clinician will assess symptom severity. There will be no
intervention in this study.

Inclusion Criteria:

- Written informed consent

- Right-handed

- (For mood disorder group only) Stable medication over the past 8 weeks OR absence of
any psychotropic medications for at least 2 weeks (for follow-up analyses testing
effects in medication-free patients):

- 6 weeks for fluoxetine,

- 6 months for neuroleptics,

- 2 weeks for benzodiazepines,

- 2 weeks for any other antidepressants

- 4 weeks for any mood-stabilizers

Exclusion Criteria:

- Suicidal ideation where outpatient treatment is determined unsafe by the study
clinician

- Pregnant women or women of childbearing potential who 1) have not completed a negative
urine pregnancy test prior to the MRI scan and/or 2) are seeking to become pregnant or
believe that they may be pregnant

- Serious/unstable medical illness (e.g., cardiovascular, renal, endocrine, neurologic
disease)

- Clinical or laboratory evidence of hypothyroidism

- History of seizure disorder, history or current diagnosis of dementia, score < 26 on
the MMSE at screening

- History or current diagnosis of the following DSM-IV psychiatric illness: organic
mental disorder, schizophrenia, schizoaffective disorder, delusional disorder,
psychotic disorder NOS, patients with mood congruent or mood incongruent psychotic
features, anorexia nervosa, obsessive compulsive disorder

- Lifetime history of stimulant dependence (e.g., cocaine, amphetamines)

- Current use of Methylphenidate (Ritalin) and other ADHD medications with dopaminergic
effects

- Patients with a lifetime history of electroconvulsive therapy (ECT)

- Failure to meet standard MRI safety requirements