| Major depressive disorder (MDD) is one of the most common and devastating psychiatric disorders. Behavioral studies have found that individuals with MDD are characterized by decreased accuracy after incorrect trials compared to correct trials, suggesting poor performance adjustments following errors. Recently, event-related potentials (ERPs) have been used to elucidate neural indices of response monitoring. The error-related negativity (ERN) is an ERP that presents as a negative deflection approximately 50 ms following an erroneous response, whereas the correct-response negativity (CRN) occurs following a correct response. The current study investigated the ERN and CRN in individuals with current MDD (CD), remitted MDD (RD) and healthy controls (HC) in order to elucidate deficits in response monitoring. By incorporating a RD group, we sought to determine whether deficits were related to current, state levels of depression. Participants performed an arrow version of the flanker task and a short/long mouth task that included trial-to-trial feedback. There were no group differences in the ERN or CRN in the flanker task, however individuals with more severe depressive symptoms had a larger CRN and smaller ERN-CRN difference. In the short/long mouth task, individuals in the CD group had a smaller ERN compared to the HC group, and the RD group had an ERN that was numerically between the HC and CD groups. Additionally, the CD group had significantly lower accuracy compared to both the HC and RD groups. Overall, these results suggest that trial-to-trial feedback may affect performance monitoring in individuals with current MDD, such that they performed worse and had a reduced error signal in the brain. Individuals with remitted MDD performed as well as healthy controls, but they also had a slightly smaller ERN in the short/long mouth task. Additionally, individuals with current MDD appeared to have increased performance monitoring on correct trials in the flanker task. This study indicates that individuals with MDD have abnormal processing of both error and correct responses, however task-related differences---in particular the presence of trial-to-trial feedback---may moderate these abnormalities. |
