A specialized inhibitory function sharpens somatosensory hand representation and enhances the production and perception of fast multifinger movements in pianists

Accurate control of fast, coordinated movements across multiple body parts characterizes experts skills, such as playing musical instruments. While performing such skillful movements, the somatosensory system is challenged to successively and in parallel process a large amount of somatosensory information originating from different body parts within a short period. Over decades, it has been posited that the cortical representations of distinct body parts are more isolated from each other in trained than untrained individuals. Several recent studies, however, have re-examined and failed to replicate it. Here, we provide compelling evidence that expert pianists possess a unique inhibitory function that isolates the somatosensory processing of different body parts in the somatosensory cortex (S1). A behavioural experiment demonstrated a superior ability to perceive fast multifinger movements in pianists than musically untrained individuals, suggesting the specialized neural process of somatosensory information originating from multiple fingers within a short period in pianists. A series of neurophysiological experiments demonstrated that pianists have a unique inhibitory function in the S1, which was activated by weak electrical stimulation to the ulnar nerve. This stimulation also increased the representational distance between fingers, which was assessed based on cortical activation patterns elicited by the passive finger movements. This indicates the strengthened independence of the individual finger representation in the somatosensory processes specifically in pianists. This stimulation also augmented both the perception and execution of the fast and complex multifinger sequential movements. In nonmusicians, neither the inhibitory effects on the somatosensory process nor enhancement of the perception of multifinger movements was induced by this stimulation. Together, these findings provide the first evidence of the experience-dependent plasticity of inhibition of the somatosensory system, which highlights its pivotal role in the isolated somatosensory processing of multiple body parts in trained individuals and enables them to control fast and complex multifinger movements.