Vedere l’errore altrui con il proprio sistema sensorimotorio: uno studio TMS in pianisti esperti

Background: Expert musical performance implies controlling fast finger-movements that cannot be corrected once the notes have been played. Thus, high-level performance is likely based on inherently anticipatory processes, scarcely influenced by auditory feedback. Aim: We tested whether the fine somatomotor skills of expert pianists may be reflected in their ability to detect others’ errors (Experiment1) and whether visual expertise alone would lead to similar results (Experiment2). Methods: Motor reactivity was indexed by TMS Motor Evoked Potentials (MEP) amplitudes recorded from relaxed thumb (the finger committing the observed error), index and little finger (controls) muscle while participants observed and categorized mute correct/incorrect fingering of piano scales. TMS was delivered 100-300-700 milliseconds after error observation. 9 expert pianists were tested (perceptuo-motor experts, Exp1). Furthermore, in order to test the role of visual expertise, 9 naïve subjects were trained to visually detect the fingering errors before being tested (visual experts, Exp2). Results: Thumb cortico-spinal reactivity (the finger committing the observed error) was selectively increased at short time-intervals (300 ms) for implicit error recognition and at 700 ms when errors were explicitly recognised. Thus, in keeping with error-related electroencephalographic brain potentials, the cortico-spinal facilitation parallels aware error perception. No such effects were found in non-pianists. Discussion: The results hint at an aware/unaware dissociation between brain responses to erroneous performance, indicating that the motor system of pianists reacts to the observation of other’s fingering errors according to somatotopic and time-locked rules. This effect is likely to be linked to motor rather than visual expertise.