The aim of this study is to investigate the neurophysiological correlates of tDCS effects in MDD patients. For this purpose, functional magnetic resonance imaging (fMRI) data is collected during the execution of a cognitive control task as well as during a resting-state condition following real or sham tDCS. It is hypothesized that prefrontal tDCS as compared to sham a) reduces distractibility by compensating for deficient DLPFC activity and b) enhances functional connectivity in networks associated with externally directed attention or cognitive engagement.