Effects of 10 Hz and 20 Hz Transcranial Alternating Current Stimulation on Automatic Motor Control

Cappon, Davide; D’Ostilio, Kevin; Garraux, Gaëtan; Rothwell, John C.; Bisiacchi, Patrizia

doi:10.1016/j.brs.2016.01.001

Cited by 35 publications

(27 citation statements)

References 29 publications

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“…Our findings of no effect of tACS on cortical excitability of the stimulated M1 seem to be in contrast to results of Cappon et al (2016) who reported a decrease in MEP size after 10 min of 20 Hz tACS over left M1. However, this effect was most strongly pronounced in follow-up tests 13 min after stimulation cessation.…”

Section: Discussioncontrasting

confidence: 99%

“…Another difference between our study and the one by Cappon et al (2016) are slightly different electrode positions (left M1 and Pz in our study, left M1 and SMA in Cappon et al, 2016). Interestingly, Cappon et al (2016) found effects of 20 Hz tACS when applied in combination with the performance of a cognitive task.…”

Section: Discussioncontrasting

confidence: 96%

“…Interestingly, Cappon et al (2016) found effects of 20 Hz tACS when applied in combination with the performance of a cognitive task. Since we also applied 20 Hz tACS, but at rest, it is possible that this frequency band is primarily effective when background activity is modulated (by task activation) and not at rest.…”

Section: Discussionmentioning

confidence: 99%

“…TACS at other frequencies (5, 10, or 40 Hz) or for different periods of time as well as tACS at other stimulation sites (parietal cortex or peripheral ulnar nerve) or with different electrode set-ups influenced cortical excitability differently (Antal et al, 2008; Chaieb et al, 2011; Feurra et al, 2011a; Schutter and Hortensius, 2011). However, Cappon et al (2016) observed reduced MEP amplitudes after 10 min of 20 Hz tACS over left M1, and Wach et al (2013) did not find any effect of 20 Hz tACS, neither on MEP size nor on cSP of the stimulated left M1. Hence, the effects of tACS remain controversial, and knowledge concerning the underlying neurophysiological mechanisms of tACS is fragmentary.…”

Section: Introductionmentioning

confidence: 96%

“…Because we used stimulation parameters comparable to Cappon et al (2016) and because, behaviorally, there is evidence that 20 Hz tACS over M1 leads to movement slowing (Pogosyan et al, 2009; Wach et al, 2013), we hypothesized that we would observe a decline in cortical excitability indicated by a decrease in MEP size and an elevation in RMT in the stimulated left M1 directly after stimulation. We further hypothesized that tACS leads to a disinhibition of the non-stimulated right M1, indicated by a reduced IHI from left to right M1 and an increased IHI from right to left M1.…”

Section: Introductionmentioning

confidence: 99%

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Transcranial Alternating Current Stimulation at Beta Frequency: Lack of Immediate Effects on Excitation and Interhemispheric Inhibition of the Human Motor Cortex

Rjosk

Kaminski

Hoff

et al. 2016

Front. Hum. Neurosci.

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Transcranial alternating current stimulation (tACS) is a form of noninvasive brain stimulation and is capable of influencing brain oscillations and cortical networks. In humans, the endogenous oscillation frequency in sensorimotor areas peaks at 20 Hz. This beta-band typically occurs during maintenance of tonic motor output and seems to play a role in interhemispheric coordination of movements. Previous studies showed that tACS applied in specific frequency bands over primary motor cortex (M1) or the visual cortex modulates cortical excitability within the stimulated hemisphere. However, the particular impact remains controversial because effects of tACS were shown to be frequency, duration and location specific. Furthermore, the potential of tACS to modulate cortical interhemispheric processing, like interhemispheric inhibition (IHI), remains elusive. Transcranial magnetic stimulation (TMS) is a noninvasive and well-tolerated method of directly activating neurons in superficial areas of the human brain and thereby a useful tool for evaluating the functional state of motor pathways. The aim of the present study was to elucidate the immediate effect of 10 min tACS in the β-frequency band (20 Hz) over left M1 on IHI between M1s in 19 young, healthy, right-handed participants. A series of TMS measurements (motor evoked potential (MEP) size, resting motor threshold (RMT), IHI from left to right M1 and vice versa) was performed before and immediately after tACS or sham using a double-blinded, cross-over design. We did not find any significant tACS-induced modulations of intracortical excitation (as assessed by MEP size and RMT) and/or IHI. These results indicate that 10 min of 20 Hz tACS over left M1 seems incapable of modulating immediate brain activity or inhibition. Further studies are needed to elucidate potential aftereffects of 20 Hz tACS as well as frequency-specific effects of tACS on intracortical excitation and IHI.

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Section: Discussioncontrasting

confidence: 99%