A Neuroimaging Investigation of Brain Activity in Major Depressive Disorder and Bipolar Disorder

Inclusion Criteria: (All three groups) * age 18-55 years * satisfactory physical health * education level and a degree of understanding to communicate effectively with the investigator c * capable of providing informed consent * female subjects of childbearing potential, a medically accepted means of contraception. Additional inclusion criteria for the patient groups include * DSM-IV-TR criteria for a diagnosis of BD or MDD * currently meeting criteria for an MDE and * a Hamilton Depression Rating Scale 17 Item (HDRS-17) score of \> 17 * blood indices within normal clinical ranges. Exclusion Criteria: (All three groups) * DSM-IV-TR criteria for substance abuse or dependence (except nicotine or caffeine) within the past 6 months * comorbid neurological or other major psychiatric disorders as defined in the DSM-IV-TR; * history of neurological trauma resulting in loss of consciousness; * uncorrected hypothyroidism or hyperthyroidism, including elevated thyroid stimulating hormone (TSH); * other unstable medical condition; * female subjects who are pregnant or nursing; Additional exclusion criteria for the BD and MDD group include: * prior failure to respond to fluoxetine and olanzapine in combination at adequate dose and duration; * evidence of serious risk of suicide based on clinician assessment and/or HRSD suicide item \> 3; * course of ECT (electroconvulsive therapy) in the preceding 6 months; * Young Mania Rating Scale (YMRS) \> 7; * administration of fluoxetine within previous 4 weeks; * treatment resistance as defined by the failure of two antidepressant trials from dissimilar classes * Hyperglycemia or diabetes mellitus as defined by a fasting blood glucose value of \> 125 mg/dl.