 The current study will address the limitations of the previous studies by characterizing D1 and D2 receptor binding in depression in extrastriatal, as well as striatal regions. PET measures of 11CNNC 112 and 18Ffallypride binding to assess D1 and D23 receptor binding potential BP, respectively, in unmedicated depressed subjects part A. The 11C-Raclopride Bolus plus constant infusion BI PET scan will assess D2 receptor binding in vivo in the striatum while the subjects perform a monetary reward task, specifically designed to induce changes in the striatal dopaminergic transmission part B. 