Corticospinal excitability is modulated by temporal feedback gaps.

The integration of sensorimotor information is important for accurate goal-directed movement and affects corticospinal excitability (CE). This study investigated CE during the motor preparation period in a goal-directed movement task with temporal feedback gaps. Each trial began with a pair of first-informative and second-response beeps presented successively as cues. Trials with temporal feedback gaps showed that virtual hand movements lagged 400 ms behind actual performed movements. The participants were instructed to prepare for movement in accordance with the first beep, start the movement upon hearing the second beep, and perform movements that were both fast and accurate to the virtual target. We delivered a single-pulse of transcranial magnetic stimulation to the first dorsal interosseous muscle 250 ms before the presentation of the response beep. Motor-evoked potential amplitudes with temporal feedback gaps were significantly higher than those without temporal feedback gaps. Moreover, motor-evoked potential amplitudes with temporal feedback gaps gradually decreased over the course of the trials, whereas those without temporal feedback gaps did not change. In summary, CE during the motor preparation period was increased by temporal feedback gaps, and this excitation decreased in accordance with adaptation to temporal feedback gaps.