Transcranial alternating current stimulation of the primary motor cortex: intensity effects

2019 ◽  
Vol 12 (2) ◽  
pp. 492
Author(s):  
I. Pozdniakov ◽  
E. Gorina ◽  
M. Feurra
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Alternating Current ◽  
Transcranial Alternating Current Stimulation ◽  
Stimulation Of

scholarly journals Online and offline effects of transcranial alternating current stimulation of the primary motor cortex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ivan Pozdniakov ◽  
Alicia Nunez Vorobiova ◽  
Giulia Galli ◽  
Simone Rossi ◽  
Matteo Feurra
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Random Noise ◽  
Single Pulse ◽  
Alternating Current ◽  
Online Application ◽  
Transcranial Random Noise Stimulation ◽  
Transcranial Alternating Current Stimulation

AbstractTranscranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that allows interaction with endogenous cortical oscillatory rhythms by means of external sinusoidal potentials. The physiological mechanisms underlying tACS effects are still under debate. Whereas online (e.g., ongoing) tACS over the motor cortex induces robust state-, phase- and frequency-dependent effects on cortical excitability, the offline effects (i.e. after-effects) of tACS are less clear. Here, we explored online and offline effects of tACS in two single-blind, sham-controlled experiments. In both experiments we used neuronavigated transcranial magnetic stimulation (TMS) of the primary motor cortex (M1) as a probe to index changes of cortical excitability and delivered M1 tACS at 10 Hz (alpha), 20 Hz (beta) and sham (30 s of low-frequency transcranial random noise stimulation; tRNS). Corticospinal excitability was measured by single pulse TMS-induced motor evoked potentials (MEPs). tACS was delivered online in Experiment 1 and offline in Experiment 2. In Experiment 1, the increase of MEPs size was maximal with the 20 Hz stimulation, however in Experiment 2 neither the 10 Hz nor the 20 Hz stimulation induced tACS offline effects. These findings support the idea that tACS affects cortical excitability only during online application, at least when delivered on the scalp overlying M1, thereby contributing to the development of effective protocols that can be applied to clinical populations.

NMDA Receptor-Mediated Motor Cortex Plasticity After 20 Hz Transcranial Alternating Current Stimulation

2018 ◽  
Vol 29 (7) ◽  
pp. 2924-2931 ◽  
Author(s):  
M Wischnewski ◽  
M Engelhardt ◽  
M A Salehinejad ◽  
D J L G Schutter ◽  
M -F Kuo ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Alternating Current ◽  
Beta Oscillations ◽  
Human Motor Cortex ◽  
After Effects ◽  
Transcranial Alternating Current Stimulation ◽  
Human Motor ◽  
Motor Cortex Plasticity

Abstract Transcranial alternating current stimulation (tACS) has been shown to modulate neural oscillations and excitability levels in the primary motor cortex (M1). These effects can last for more than an hour and an involvement of N-methyl-d-aspartate receptor (NMDAR) mediated synaptic plasticity has been suggested. However, to date the cortical mechanisms underlying tACS after-effects have not been explored. Here, we applied 20 Hz beta tACS to M1 while participants received either the NMDAR antagonist dextromethorphan or a placebo and the effects on cortical beta oscillations and excitability were explored. When a placebo medication was administered, beta tACS was found to increase cortical excitability and beta oscillations for at least 60 min, whereas when dextromethorphan was administered, these effects were completely abolished. These results provide the first direct evidence that tACS can induce NMDAR-mediated plasticity in the motor cortex, which contributes to our understanding of tACS-induced influences on human motor cortex physiology.

scholarly journals Multivariate pattern analysis reveals location specific aftereffects of 10Hz motor cortex transcranial alternating current stimulation

2021 ◽  
Author(s):  
Elinor Tzvi ◽  
Jalal Alizadeh ◽  
Christine Schubert ◽  
Joseph Classen
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Pattern Analysis ◽  
Premotor Cortex ◽  
Alternating Current ◽  
Eeg Signal ◽  
Multivariate Pattern Analysis ◽  
Eeg Signals ◽  
Transcranial Alternating Current Stimulation ◽  
Multivariate Pattern

Background: Transcranial alternating current stimulation (tACS) may induce frequency-specific aftereffects on brain oscillations in the stimulated location, which could serve as evidence for region-specific neuroplasticity. Aftereffects of tACS on the motor system remain unknown. Objective: To find evidence for aftereffects in short EEG segments following tACS to two critical nodes of the motor network, namely, left motor cortex (lMC) and right cerebellum (rCB). We hypothesized that aftereffects of lMC will be stronger in and around lMC compared to both active stimulation of rCB, as well as inactive (sham) control conditions. Methods: To this end, we employed multivariate pattern analysis (MVPA), and trained a classifier to distinguish between EEG signals following each of the three stimulation protocols. This method accounts for the multitude facets of the EEG signal and thus is more sensitive to subtle modulation of the EEG signal. Results: EEG signals in both theta (θ, 4-8Hz) and alpha (α, 8-13Hz) were better classified to lMC-tACS compared to rCB-tACS/sham, in and around lMC-tACS stimulation locations (electrodes FC3 and CP3). This effect was associated with a decrease in power following tACS. Source reconstruction revealed significant differences in premotor cortex but not in primary motor cortex as the computational model suggested. Correlation between classification accuracies in θ and α in lMC-tACS was stronger compared to rCB-tACS/sham, suggesting cross-frequency effects of tACS. Nonetheless, θ/α phase-coupling did not differ between stimulation protocols. Conclusions: Successful classification of EEG signals to left motor cortex using MVPA revealed focal tACS aftereffects on the motor cortex, indicative of region-specific neuroplasticity.

Multifocal Noninvasive Magnetic Stimulation of the Primary Motor Cortex in Type 1 Myotonic Dystrophy –A Proof of Concept Pilot Study

2021 ◽  
pp. 1-10
Author(s):  
Ericka Greene ◽  
Jason Thonhoff ◽  
Blessy S. John ◽  
David B. Rosenfield ◽  
Santosh A. Helekar
Keyword(s):  
Motor Cortex ◽  
Myotonic Dystrophy ◽  
Muscle Function ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Compound Muscle Action Potential ◽  
Sham Stimulation ◽  
Stimulation Of

Background: Repeated neuromuscular electrical stimulation in type 1 Myotonic Dystrophy (DM1) has previously been shown to cause an increase in strength and a decrease in hyperexcitability of the tibialis anterior muscle. Objective: In this proof-of-principle study our objective was to test the hypothesis that noninvasive repetitive transcranial magnetic stimulation of the primary motor cortex (M1) with a new portable wearable multifocal stimulator causes improvement in muscle function in DM1 patients. Methods: We performed repetitive stimulation of M1, localized by magnetic resonance imaging, with a newly developed Transcranial Rotating Permanent Magnet Stimulator (TRPMS). Using a randomized within-patient placebo-controlled double-blind TRPMS protocol, we performed unilateral active stimulation along with contralateral sham stimulation every weekday for two weeks in 6 adults. Methods for evaluation of muscle function involved electromyography (EMG), hand dynamometry and clinical assessment using the Medical Research Council scale. Results: All participants tolerated the treatment well. While there were no significant changes clinically, EMG showed significant improvement in nerve stimulus-evoked compound muscle action potential amplitude of the first dorsal interosseous muscle and a similar but non-significant trend in the trapezius muscle, after a short exercise test, with active but not sham stimulation. Conclusions: We conclude that two-week repeated multifocal cortical stimulation with a new wearable transcranial magnetic stimulator can be safely conducted in DM1 patients to investigate potential improvement of muscle strength and activity. The results obtained, if confirmed and extended by future safety and efficacy trials with larger patient samples, could offer a potential supportive TRPMS treatment in DM1.

Sign in / Sign up

Export Citation Format

Share Document