Fig 3. Activation maps and timecourses for event-related beta power expressed as percent change from pre-flanker baseline.

‘F’ and ‘T’ correspond to flanker (at -200 ms) and target (0 ms) presentation respectively. Beta power in the early time window (150-300ms), highlighted in blue, is sensitive to response preparation primed by the flanker: in this example, CO and SI prime the left hemisphere (correct response hand), as shown with greater beta decrease (timecourse shown in bottom right panel). In RI, the right hemisphere is incorrectly primed by the flanker as shown with beta decrease to RI (timecourse shown in upper right panel). Upon the presentation of the response-incongruent target, the response preparation is switched to the opposite hand to make a correct response. During the late time window (450-600ms), highlighted in green, stronger beta decrease in the correctly-responding left hemisphere is seen in all conditions. Therefore, the relative changes in beta power track motor preparation in real time. Only correct trials requiring a right-hand response are shown here, but the findings on left-hand trials are a mirror image of the pattern shown above.