Depression symptom severity and error-related brain activity.

The present study examined the relationship between depression and neural correlates of response monitoring using event-related potentials (ERPs). The error-related negativity (ERN) and correct response negativity (CRN) are ERPs that present as a negative deflection approximately 50 ms following an erroneous and correct response, respectively; the error positivity (Pe) is a positive deflection approximately 200 ms following an erroneous response. Some studies have reported an increased ERN in individuals with major depressive disorder (MDD), but others have failed to find such differences. Results on the Pe in MDD have also been mixed. In the current study, unmedicated individuals with MDD (N=22) and healthy controls (N=22) performed an arrow version of the flanker task. Although these groups did not differ on the ERN or CRN overall, depression severity related to the CRN and the differentiation between the ERN and CRN (DeltaERN) in the MDD group: more severe depression was associated with an increased CRN and a reduced DeltaERN. Additionally, the difference between the Pe on error and correct trials (DeltaPe) was reduced among individuals with MDD compared to healthy controls. These data suggest that individuals with severe depression have a reduced differentiation between error and correct trials on ERPs that index error monitoring and awareness.