We aim to study potential MR imaging biomarkers derived from f-MRI (functional magnetic resonance imaging), DTI (diffusion tensor imaging), and proton MR (magnetic resonance) spectroscopy in patients undergoing ECT for severe depression related to major depressive disorder (MDD) and bipolar disorder (BD). Subjects will undergo an MR imaging session of 1.5 hrs duration at 3 time points: A) prior to initial ECT therapy; B) within 24 hrs following initial ECT therapy; C) 60-days following initial ECT therapy. Imaging measures will be correlated with clinical measures of disease severity at time points A and B in order to ascertain the potential utility of imaging biomarkers for prediction of therapy response. Our goal is to identify MR imaging biomarkers that may convey prognostic information which could be useful in the management of depression. Secondarily, the multi-modality MR imaging approach yielded functional connectivity data (both in the resting state and using an emotional regulation paradigm), white matter tract-based spatial statistics, and proton MR spectroscopy-derived metabolic information will facilitate an exploration of the physiologic mechanisms of ECT therapy. Twelve subjects will be recruited from a clinical population already diagnosed with a depressive episode requiring ECT. Patients will they be invited to participate in our study only after they have consented for ECT. Written consent will be obtained before any study procedures is conducted. Patients meeting any of the exclusion criteria will be excluded from participating in the study. Collected data will include: a) measures of depression severity (HAM-D, BDI) and b) multi-modality imaging data (fMRI, diffusion tensor imaging, proton MR spectroscopy, and anatomic MR imaging).