Bilateral effect of a unilateral voluntary modulation of physiological tremor

ObjectiveVerify whether a unilateral physiological tremor modulation attempt has a bilateral effect on central oscillators responsible for physiological tremor.MethodsBilateral finger physiological tremor was recorded in 35 right-handed participants with laser displacement sensors in: (A) control condition, (B) modulation attempt of physiological tremor of the right index finger, (C) modulation attempt of physiological tremor of the right index finger by using co-contraction as a means to stabilize the finger.ResultsPhysiological tremor amplitude was significantly reduced between the control and modulation conditions for the right index finger. Physiological tremor amplitude was also significantly reduced for the left index finger. Regression analysis of oscillation amplitudes showed little relationship between both fingers, even during modulation attempts. The lack of relationship between fingers is also evident by low coherence values obtained in the control and modulation conditions. The coherence in the co-activation condition was significantly higher, albeit still low, in each frequency band.ConclusionOur results confirm that physiological tremor can be voluntarily reduced, and this reduction is bilateral. The modulation attempt did not however increase the frequency relationship between both sides.SignificanceA central command aiming at modulating tremor amplitude will not increase the synchronization between oscillators responsible for the central components of physiological tremor.