Figure 3.

(A) Group-averaged time-frequency spectrogram during flanker task performance. Time (in ms) is denoted on the x-axis, with 0 ms defined as the onset of the flanker stimuli. Frequency (in Hz) is shown on the y-axis. All signal power data is expressed as the percent difference from baseline (−450 to −50 ms), with the color legend shown at the top. Data represent a group-averaged gradiometer sensor that was near the fronto-parietal region in each participant (the same sensor was selected in each participant). During task performance, alpha activity in this brain area strongly decreased (i.e., desynchronization) and theta activity strongly increased (i.e., synchronization). Time periods with significant oscillatory activity (relative to baseline) were subjected to beamforming. The time-frequency windows subjected to beamforming are enclosed within the dashed boxes. (B) Gradiometer sensors exhibiting significant alpha responses (9–12 Hz) in the enclosed range shown in (A) are highlighted in blue in a 2D map of the sensor array. (C) Same as (B) except that the sensors highlighted in red had significant theta responses (3–7 Hz) through the enclosed time window.