Figure 2.

A, The preparatory cue consisted of a letter: “x” indicated a forthcoming left hand movement and “o” indicated a right hand movement. The imperative signal was an arrow presented at the screen center. B, Sequence and timing of events in experiments 2 and 3: A fixation marker (100 ms) was followed 900 ms later, by a preparatory cue that lasted for a fixed delay (100 ms). An imperative signal indicating the required response appeared after a delay (Exp. 2: 900 ms; Exp. 3: 900–1200 ms). A single TMS or electrical pulse was applied over the right M1 or the left median nerve, respectively, during one of two epochs (baseline, delay). In this example, a TMS pulse was applied during the delay period of a right index finger abduction (Exp. 2) or wrist flexion (Exp. 3) movement.