Differences in cross modulation of physiological tremor in pianists and nonmusicians.

The study was undertaken to investigate the contralateral overflow effect on physiological tremors in pianists and nonmusicians. Group differences in cross modulation on underlying finger fractionated movement were characterized. Physiological tremors of the right index, middle, ring, and little fingers were recorded in 12 right-handed pianists and 12 matched nonmusician controls; meanwhile, two contralateral resistance protocols (unilateral handgrip using the left hand at slight and maximal efforts) were randomly conducted. Digit tremors of the control and pianist groups were differentially modulated with the resistance protocols. An increase in gripping force led to cross excitations over 8-12 Hz digit tremors and interdigit tremor coupling for the nonmusicians. An opposite cross effect was noted for the pianists, who exhibited significant tremor suppression and the release of interdigit tremor coupling. Further analysis of tremor dynamics revealed that contralateral gripping reduced the complexity of digit tremors of the pianists but added to the tremor complexity of the nonmusicians. Cross modulation on digit tremors suggests that pianists could centrally suppress unintended motor excitation across the midline. When the opposite hand is active, pianists have superior finger independence that allows them to achieve artistic aspects of musical performance.