The investigators are doing this study to find out if they can use electroencephalographic (EEG) recordings, which measure brain waves, to predict response to antidepressant treatments, as well as to distinguish patients who have depression from those who do not. In particular the investigators want to test the usefulness of a new type of analysis of EEG recordings called brain network activation or BNA. BNA allows to identify patterns of activation in brain networks and to track their changes over time.