3D plots showing the results of trial-by-trial modeling of fMRI signal associated with RTs ranging from 0.2 s faster than the mean RT for a given individual, to 0.7 s slower than the mean RT. The signal time course at the mean RT is marked in green. a, Medial frontal region; b, intraparietal sulcus; c, lateral occipital (extrastriate) cortex. Note that peak signal in the frontoparietal control regions increased with slower responses, albeit to a lesser extent during SD. In contrast, response slowing was associated with decrease in extrastriate peak signal during SD.