Electrophysiological results of the stop signal task. A, Top, ERPs time-locked to stop signals at a central channel cluster. Bottom, Topography of P3 component. The highlighted channels show the central cluster. B, Top, ERSPs of successful versus unsuccessful stops at a frontal channel cluster. Right, Topography β (18-30 Hz) power from 200 to 400 ms, with highlighted channels showing the frontal cluster. Bottom, Same as in top plot, but statistically masked to highlight the significant frontal β cluster.