Fig. 4.

Distribution of stop-event-related potentials (ERPs) in successful-stop (SS) trials. A: average stop-ERPs (solid red curves) of SS trials centered on stop-signal appearance corresponding to the selected channels for an example epileptic patient. Gray areas represent time intervals at which the stop-ERP was significantly different from 0 (Wilcoxon signed-rank test, P < 0.01). Brodmann's areas (BAs) over which electrodes were positioned are indicated. Colored areas identify electrodes placed over the primary motor cortex (red; BA4), premotor cortex (yellow; BA6), and dorsolateral prefrontal cortex (green; BA9). B: histogram of the stop-ERP sizes shown in A. Stop-ERP sizes were computed as the integral of absolute values of stop-ERP voltage deflections in the interval periods marked by gray areas within SSRT. Dashed line represents the threshold value for selecting channels with large enough stop-ERPs used for population analyses. C: number of channels showing large enough average stop-ERPs across 5 patients (n = 39) grouped by BA. Blue bar (others) represents those areas where channels were not selected more than twice across all patients. D: box plot of stop-ERP onsets measured with respect to the end of SSRT across all selected channels in all patients. Stop-ERP onset was defined as the first time that an electrode voltage was significantly different from 0. Average onset times are indicated by diamonds. Bars indicate the first and the third quartile. Vertical lines indicate the extreme time lags in the channel group. CCBY 4.0, http://journal.frontiersin.org/article/10.3389/fnsys.2014.00206/full.