Links Between Altered Feedback Learning and Symptoms of Depression: Insights From the FRN and Feedback-Locked N170.

Blunted electrophysiological and striatal responses to reward have been suggested as biomarkers or endophenotypes for depression. However, previous studies did not differentiate between learning from immediate and learning from delayed feedback, which involves different neural structures. The aim of the present study was to clarify whether depression alters learning from both immediate and delayed feedback. We investigated the influence of current and past depressive symptom severity and familial history of depression in a mixed clinical and nonclinical sample of 45 individuals on two event-related potential (ERP) components, namely, the feedback-related negativity (FRN) and N170. In the past, the FRN has been reported to primarily reflect the processing of immediate feedback, while the N170-most commonly studied in relation to face processing-appeared to represent the processing of delayed feedback. We found that performance in a probabilistic feedback learning task with immediate and delayed feedback was reduced for more severe depressive symptoms, regardless of feedback timing. Surprisingly, the FRN was not affected by current or past depressive symptom severity or familial vulnerability to depression. However, we found depression-related changes in the N170 for both immediate and delayed feedback processing: currently experienced depressive symptoms were associated with poorer encoding of prediction errors in the N170. In addition, a family history of depression was associated with lower sensitivity to the valence of feedback in the N170. In summary, the N170 may emerge as a novel, important biomarker in clinical research on depression and feedback-based learning.