Magnetic stimulation intensity modulates motor inhibition

Berger, Uri; Korngreen, Alon; Bar‐Gad, Izhar; Friedman, A.; Wolfus, Shuki; Yeshurun, Y.; Lavidor, Michal

doi:10.1016/j.neulet.2011.09.004

Cited by 19 publications

(13 citation statements)

References 32 publications

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“…With 1 mA an increase of the MEP amplitudes can be seen. This suggests that inhibitory circuits can be excited preferentially with lower intensities, an effect which has also been documented for TMS (Berger et al, 2011). Nevertheless, the reason for this observed reversal in the direction of MEP effects induced by higher frequency stimulation at different intensities has not been clarified yet.…”

Section: Acs Effects In the Normal Brainsupporting

confidence: 57%

Transcranial alternating current stimulation (tACS)

Antal¹,

Paulus²

2013

Front. Hum. Neurosci.

427

355

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Transcranial alternating current stimulation (tACS) seems likely to open a new era of the field of noninvasive electrical stimulation of the human brain by directly interfering with cortical rhythms. It is expected to synchronize (by one single resonance frequency) or desynchronize (e.g., by the application of several frequencies) cortical oscillations. If applied long enough it may cause neuroplastic effects. In the theta range it may improve cognition when applied in phase. Alpha rhythms could improve motor performance, whereas beta intrusion may deteriorate them. TACS with both alpha and beta frequencies has a high likelihood to induce retinal phosphenes. Gamma intrusion can possibly interfere with attention. Stimulation in the “ripple” range induces intensity dependent inhibition or excitation in the motor cortex (M1) most likely by entrainment of neuronal networks, whereas stimulation in the low kHz range induces excitation by neuronal membrane interference. TACS in the 200 kHz range may have a potential in oncology.

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Section: Acs Effects In the Normal Brainsupporting

confidence: 57%

Transcranial alternating current stimulation (tACS)

Antal¹,

Paulus²

2013

Front. Hum. Neurosci.

427

355

View full text Add to dashboard Cite

show abstract

“…It has also been suggested that the cerebrocortical excitability depends on stimulation parameters such as stimulation intensity; these results agree with those in previous studies. 8,16 Moreover, this study changed the direction of the stimulation coil, and when the induced current was in the AP direction, significant modulation of motor cortex excitability was not obtained. The direction of the stimulation coil is thought to be an important parameter.…”

Section: Discussionmentioning

confidence: 84%

Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation

Sato

Torii

Iwahashi

et al. 2014

Journal of Applied Physics

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The present study analyzed the effects of monophasic magnetic stimulation to the motor cortex. The effects of magnetic stimulation were evaluated by analyzing the motor evoked potentials (MEPs). The amplitude and latency of MEPs on the abductor pollicis brevis muscle were used to evaluate the effects of repetitive magnetic stimulation. A figure eight-shaped flat coil was used to stimulate the region over the primary motor cortex. The intensity of magnetic stimulation was 120% of the resting motor threshold, and the frequency of magnetic stimulation was 0.1 Hz. In addition, the direction of the current in the brain was posterior-anterior (PA) or anterior-posterior (AP). The latency of MEP was compared with PA and AP on initial magnetic stimulation. The results demonstrated that a stimulus in the AP direction increased the latency of the MEP by approximately 2.5 ms. MEP amplitude was also compared with PA and AP during 60 magnetic stimulations. The results showed that a stimulus in the PA direction gradually increased the amplitude of the MEP. However, a stimulus in the AP direction did not modulate the MEP amplitude. The average MEP amplitude induced from every 10 magnetic pulses was normalized by the average amplitude of the first 10 stimuli. These results demonstrated that the normalized MEP amplitude increased up to approximately 150%. In terms of pyramidal neuron indirect waves (I waves), magnetic stimulation inducing current flowing backward to the anterior preferentially elicited an I1 wave, and current flowing forward to the posterior elicited an I3 wave. It has been reported that the latency of the I3 wave is approximately 2.5 ms longer than the I1 wave elicitation, so the resulting difference in latency may be caused by this phenomenon. It has also been reported that there is no alteration of MEP amplitude at a frequency of 0.1 Hz. However, this study suggested that the modulation of MEP amplitude depends on stimulation strength and stimulation direction.

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“…MEPs were measured before and after rTMS was applied at various stimulus conditions of intensity and pulse number. However, rTMS affects individuals differently . Therefore, we performed cluster analysis to classify the study subjects into groups.…”

Section: Methodsmentioning

confidence: 99%

“…Both 85% and 115% RMT rTMS increased the RMT and 115% rTMS decreased the MEP amplitude . However, it was indicated that the MEP increased when using 1 Hz rTMS depending on the stimulation parameters and on the individual . For the reason noted above, on some occasions, the stimulation parameters are not set objectively to apply rTMS.…”

Section: Introductionmentioning

confidence: 99%

Prediction of cortical excitability induced by 1 Hz rTMS

Nojima

Iramina

2017

IEEJ Transactions Elec Engng

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The aim of this study was to develop a model that predicts the effects of repetitive transcranial magnetic stimulation (rTMS), allowing stimulation of parameters for individual subjects. Modulation of cortical excitability induced by rTMS can be evaluated through motor evoked potential (MEP) amplitude. We establish a model that can predict how the MEP amplitude is modulated by entering rTMS intensity and number of pulses. First, MEPs are measured under various rTMS conditions of stimulus intensity and number of pulses. Then, cluster analysis is performed to classify the subjects, as rTMS affects individuals differently. Finally, a predictive model is created by applying multiple regression analysis to the data from each cluster. As a result, subjects are classified into two groups. For Cluster A, the inhibitive effect of rTMS is difficult to induce and the facilitative effect is induced depending on the stimulus condition. Then, the average predictive error is 46.19%. For Cluster B, the inhibitive effect is strongly induced by rTMS, and the average error is 20.25%. In the model, for both clusters, about 90% of measurement data is in the predictive interval. This paper describes the development of our prediction model and its efficiency.

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Magnetic stimulation intensity modulates motor inhibition

Cited by 19 publications

References 32 publications

Transcranial alternating current stimulation (tACS)

Transcranial alternating current stimulation (tACS)

Modulation of amplitude and latency of motor evoked potential by direction of transcranial magnetic stimulation

Prediction of cortical excitability induced by 1 Hz rTMS

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