Transcranial Alternating Current Stimulation With Gamma Oscillations Over the Primary Motor Cortex and Cerebellar Hemisphere Improved Visuomotor Performance.

Shota Miyaguchi,Mitsuhiro Masaki,Naofumi Otsuru,Hideaki Onishi,Yasuto Inukai,Sho Kojima,Kei Saito

doi:10.3389/fnbeh.2018.00132

Shota Miyaguchi, Mitsuhiro Masaki + Show 5 more

Open Access

https://doi.org/10.3389/fnbeh.2018.00132

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Abstract

Transcranial alternating current stimulation (tACS) can be used to modulate oscillatory brain activity. In this study, we investigated whether tACS applied over the primary motor cortex (M1) and cerebellar cortex region improved motor performance. We applied tACS (1.0 mA) to 20 healthy adults while they performed an isometric force task with some visuomotor control using their right index finger. Gamma (70 Hz) oscillations in the Experiment 1 or beta (20 Hz) oscillations in the Experiment 2 were applied for 30 s over the left M1, right cerebellar hemisphere or both regions (“M1-Cerebellum”), and errors performing the task were compared. Beta-oscillation tACS did not affect motor performance. With the gamma-oscillation tACS, a negative correlation was found between the difference of error in the M1-Cerebellum condition and the number of errors in the sham condition (P = 0.005, Pearson’s r = −0.597), indicating that motor performance improved with M1-Cerebellum tACS for subjects with low motor performance in the sham condition. Those who performed poorly in the sham condition made significantly fewer errors with M1-Cerebellum tACS (P = 0.004). Thus, for subjects with poorer motor performance, tACS with gamma oscillations applied over the M1 and contralateral cerebellar hemisphere improved their performance.

Highlights

Oscillatory brain activity plays an important role in various brain functions, such as cognition, arousal, memory and motor system
This indicated that, for subjects with a poorer motor performance during the sham condition, their performance improved with M1-Cerebellum Transcranial alternating current stimulation (tACS)
The results demonstrated that gamma tACS over M1 and the contralateral cerebellar hemisphere did improve motor performance for the subjects with lower motor performance

Summary

Introduction

Oscillatory brain activity plays an important role in various brain functions, such as cognition, arousal, memory and motor system. In the primary motor cortex (M1), beta band activity has been shown to decrease prior to and during voluntary movement (Muthukumaraswamy, 2011) and to increase during isometric contraction (Brown and Marsden, 1998), whereas gamma band activity increases prior to and during motor performance (Hamada et al, 1999; Muthukumaraswamy, 2011) and affects the motor response time (Shibata et al, 1999). Recent research has focused on artificially modulating oscillatory activity in the gamma bands in the motor-related area of the brain to improve motor performance.

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