Effects of transcranial alternating current stimulation on repetitive finger movements in healthy humans

Publication date: January 2019

Source: Clinical Neurophysiology, Volume 130, Issue 1

Author(s): G. Paparella, A. Guerra, M. Bologna, A. Suppa, D. Colella, V. Di Lazzaro, P. Brown, A. Berardelli

Transcranial Alternating Current Stimulation (tACS) is a non-invasive technique that can entrain brain oscillations. Few studies have investigated the effects of tACS on voluntary movements in healthy humans. We investigated whether tACS, delivered over M1 at beta and gamma frequencies, has any effect on repetitive finger tapping as assessed by means of kinematic analysis. Eighteen healthy subjects were enrolled. Objective measurements of repetitive finger tapping were obtained by using a motion analysis system. M1 excitability was assessed by single pulse TMS and measuring the amplitude of motor-evoked potentials. Movement kinematics and M1 excitability measures were collected during beta, gamma and sham tACS as well as off stimulation. Beta tACS led to an early amplitude decrement during repetitive finger tapping. Gamma tACS had the opposite effect. The progressive but short-lived modulatory effect of beta and gamma tACS on amplitude decrement was marked during the first movements of the motor sequence. No effect of tACS were found on other movement parameters neither on MEP amplitude. tACS modulates finger tapping in a frequency-dependent manner with no concurrent changes in corticospinal excitability. Thus, cortical beta and gamma oscillations are involved in the motor control of repetitive finger movements.

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