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

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.

The role of alpha oscillations in a premotor-cerebellar loop in modulation of motor learning: insights from transcranial alternating current stimulation

“…Indeed, in Experiment 2 we found that 10Hz rCB tACS, but not lM1 tACS, led to declined learning performance when compared to sham. Only few studies investigated the effect of cerebellar tACS on motor performance (Miyaguchi et al, 2018;Naro et al, 2016). These studies show that higher frequency tACS to the cerebellum led to improved motor performance, but contrary to our results, found no effect at 10Hz.…”

Non-Invasive Cerebellar Stimulation in Neurodegenerative Ataxia: A Literature Review

“…Moreover, transcranial alternating current stimulation (tACS) also has recently emerged as a new technique to modulate cortical oscillations and entrain brain rhythms in specific frequencies [101]. By applying cerebellar tACS at a frequency matching the basal firing rate of Purkinje cells (50 Hz), researchers have shown that tACS may modulate CBI and improve the performance of a motor tasks in healthy controls [102][103][104][105][106]. Whether these novel types of stimulation might be effective also in the treatment of cerebellar ataxias is still unknown.…”

“…Critically, evaluation of target engagement using imaging or physiologic biomarkers, as well as the assessment of "dose" by using modelling to calculate the induced currents in the brain to define individual stimulation parameters, would be essential. Moreover, the cerebellum can show significant structural changes in term of climbing fiber Purkinje cell and parallel fiber Purkinje cell wirings in cerebellar ataxia and other disorders [102][103][104][105][106], and some wiring features can be rapidly changed within days and affect cerebellar synchronization [107]. These structural changes may affect the effect of TMS and tDCS, and should be considered future studies.…”

Connectivity of the Frontal Cortical Oscillatory Dynamics Underlying Inhibitory Control During a Go/No-Go Task as a Predictive Biomarker in Major Depression

“…This abnormality in beta oscillations in the fronto-parietal network could indicate a crucial piece of information about impaired ability in executive processing. However, a surge in gamma band activity has been detected before and during motor performance ( 43 , 45 ) which also affected motor response time ( 46 ). It has been previously reported that gamma oscillations relied on GABAergic neuronal inhibition circuits ( 47 , 48 ).…”

“…The outcome of a movement task which requires motor control may be improved by modulating the activity of both M1 and the sub-cortex region rather than M1 activity alone ( 43 , 60 ). Authors of existing studies about the inhibitory control network in the human brain have repeatedly found that the activation of preSMA and r IFG is crucial for inhibitory control during stop-signal and go/no-go task.…”