Greater activation of the "default" brain regions predicts stop signal errors.

Previous studies have provided evidence for a role of the medial cortical brain regions in error processing and post-error behavioral adjustment. However, little is known about the neural processes that precede errors. Here in an fMRI study we employ a stop signal task to elicit errors approximately half of the time despite constant behavioral adjustment of the observers (n=40). By comparing go trials preceding a stop error and those preceding a stop success, we showed that (at p<0.05, corrected for multiple comparisons) the activation of midline brain regions including bilateral precuneus and posterior cingulate cortices, perigenual anterior cingulate cortices and transverse frontopolar gyri precedes errors during the stop signal task. Receiver operating characteristic (ROC) analysis based on the signal detection theory showed that the activity in these three regions predicts errors with an accuracy between 0.81 and 0.85 (area under the ROC curve). Broadly supporting the hypothesis that deactivation of the default mode circuitry is associated with mental effort in a cognitive task, the current results further indicate that greater activity of these brain regions can precede performance errors.