Fig. 1.

Experimental design. A Each participant underwent a skilled and non-skilled acquisition session in a randomised order. Skill was quantified at the beginning and end of each session. Transcranial magnetic stimulation (TMS) with posterior–anterior (PA) current was used to measure short-interval intracortical facilitation (SICF) and corticomotor excitability, whereas anterior–posterior (AP) current was used to measure short-interval intracortical inhibition (SICI). Neurophysiological measures were probed before, mid, and after each 10-block training session. B The on-screen display for the skilled sequential isometric force task (left) and non-skilled unitary isometric force task (right). Each trial required index finger abduction against a force transducer. In the skilled task, participants reached the targets in the order red–blue–green–yellow–white. In the non-skilled task, participants were required to reach the green target five times. C A representative force peak from a single participant performing the five-sequence target sequence (left) and the unitary target sequence (right) with the nondominant index finger against the force transducer