Inclusief Code onderzoek: EUR FSW 19 This study examined the role of the medial frontal cortex in the processing of valence and validity of performance feedback using a time-estimation paradigm. Participants had to produce 1 s intervals followed by positive and negative feedback that could be valid or invalid (i.e., related or unrelated to task performance). Performance results showed that participants used the validity information to adjust their time estimations to negative feedback. The rostral cingulate zone (RCZ) was more active after valid feedback than after invalid feedback, but was insensitive to the valence of the feedback. The rostral anterior cingulate cortex (rACC), posterior cingulate and right superior frontal gyrus, however, appeared to be primarily sensitive to the valence of the feedback: being more active after positive feedback. The results are discussed along the lines of the ACC's cognitive and affective subdivisions and their structural and functional connections. (C) 2011 Elsevier Inc. All rights reserved.