Medial prefrontal cortex predicts and evaluates the timing of action outcomes.

The medial prefrontal cortex (mPFC) is active in conditions of performance monitoring including error commission and response conflict, but the mechanisms underlying these effects remain in dispute. Recent work suggests that mPFC learns to predict the value of actions, and that error effects represent a discrepancy between actual and expected outcomes of an action. In general, expectation signals regarding the outcome of an action may have a temporal structure, given that outcomes are expected at specific times. Nonetheless, it is unknown whether and how mPFC predicts the timing as well as the valence of expected action outcomes. Here we show with fMRI that otherwise correct feedback elicits apparent error-related activity in mPFC when delivered later than expected, suggesting that mPFC predicts not only the valence but also the timing of expected outcomes of an action. Results of a model-based analysis of fMRI data suggested that regions in the caudal cingulate zone, dorsal mPFC, and dorsal anterior cingulate cortex were jointly responsive to unexpectedly delayed feedback and negative feedback outcomes. These results suggest that regions in anterior cingulate and mPFC may be more broadly responsive to outcome prediction errors, signaling violations of both predicted outcome valence and predicted outcome timing, and the results further constrain theories of performance monitoring and cognitive control pertaining to these regions.