Selective increase in motor excitability with intraactive (self) versus interactive touch.

Corticomotor facilitation was investigated using transcranial magnetic stimulation in healthy young adults when they actively stroked either their own left palm (intraactive) or the experimenter's palm (interactive touch) with their right index finger. We predicted, based on the sensory cancellation hypothesis, that corticomotor facilitation would be lower with intraactive touch. Motor evoked potential amplitude in the right first dorsal interosseous was affected by mode of touch, but not by sex. In contrast to our prediction, motor evoked potential facilitation was larger (mean 14%) during intraactive touch. The present results are in agreement with recent evidence suggesting that self-touch represents a unique class of sensorimotor experiences that are critical for the elaboration of internal body structure representation.