Introduction

It is common knowledge that ‘practice makes perfect’. Many types of human motor behaviour seem to rely heavily on the fact that the performance of subsequent movements is facilitated by prior performance of similar movements. Therefore, the capacity to build a memory trace of previously practised movements appears to be a fundamental property of the human motor system. Recent studies have focused on this theme in an attempt to gain insight into the physiology of motor memory. Such understanding may contribute to the development of techniques to promote recovery of function following brain damage in humans.

Use-dependent plasticity

Since the 1990s, numerous reports, by employing TMS, demonstrated plasticity induced by motor learning, motor practice or use. One of the earliest reports showed that the excitability of the muscle representation of the ‘reading’ finger is increased in Braille readers (Pascual-Leone et al., 1993). Pearce and coworkers found that, in highly trained Olympic badminton players, the excitability of the first dorsal interosseus muscle of the skilled hand is increased and its topographical representation is altered when compared to the unskilled hand or to the representations in untrained players (Pearce et al., 2000). These studies provided evidence that the organization of motor activity is modifiable. They also raised questions about the particular factors involved in long-term practice that were instrumental in triggering these profound changes.