Medial prefrontal cortex activity correlates with time-on-task: what does this tell us about theories of cognitive control?

A paper by Grinband et al. (this issue) argues that dorsal medial prefrontal cortex (mPFC) activity reflects time-on-task rather than conflict or error likelihood. In this commentary, Brown suggests that the findings are consistent with a new model in which mPFC learns to predict the nature and timing of action outcomes. The new model predicts that time-on-task effects coexist with distinct error likelihood effects, a result which is consistent with other recent findings from fMRI and monkey neurophysiology.