Figure 2. Power effects. a, Correct minus error trial difference in pre-cue time/frequency data. b–d, Shown above is the gamma effect (right box in a), which consisted of greater power 100–0 ms before cue onset on error trials and an estimated source location of posterior parietal cortex/precuneus, depicted in the topography (b), time course (c), and estimated cortical source location (d). e–g, Below is the beta effect (left box in a), which consisted of less power 400–0 ms before the gap onset on error trials and an estimated source location of anterior cingulate cortex depicted in the time course (e), topography (f), and the estimated cortical source location (g). Source images are in neurological convention (left is left); coordinates depicted in d and g are Talairach space.