PDF(Pubmed)
Abstract：
BACKGROUND: Transcranial magnetic stimulation (TMS), when applied over the primary motor cortex, elicits a motor-evoked potential (MEP) in electromyograms measured from peripheral muscles. MEP amplitude has often been observed to fluctuate trial to trial, even with a constant stimulus. Many factors cause MEP fluctuations in TMS. One of the primary factors is the weak stationarity and instability of cortical activity in the brain, from which we assumed MEP fluctuations originate. We hypothesized that MEP fluctuations are suppressed when TMS is delivered to the primary motor cortex at a time when several electroencephalogram (EEG) channels measured on the scalp are highly similar in the frequency domain.
OBJECTIVE: We developed a TMS triggering system to suppress MEP fluctuations using EEG coherence analysis, which was performed to detect the EEG signal similarity between the 2 channels in the frequency domain.
METHODS: Seven healthy adults participated in the experiment to confirm whether the TMS trigger system works adequately, and the mean amplitude and coefficient of the MEP variation were recorded and compared with the values obtained during the control task. We also determined the experimental time under each condition and verified whether it was within the predicted time.
RESULTS: The coefficient of variation of MEP amplitude decreased in 5 of the 7 participants, and significant differences (P=.02) were confirmed in 2 of the participants according to an F test. The coefficient of variation of the experimental time required for each stimulus after threshold modification was less than that without threshold modification, and a significant difference (P<.001) was confirmed by performing an F test.
CONCLUSIONS: We found that MEP could be suppressed using the system developed in this study and that the TMS trigger system could also stabilize the experimental time by changing the triggering threshold automatically.
OBJECTIVE: We developed a TMS triggering system to suppress MEP fluctuations using EEG coherence analysis, which was performed to detect the EEG signal similarity between the 2 channels in the frequency domain.
METHODS: Seven healthy adults participated in the experiment to confirm whether the TMS trigger system works adequately, and the mean amplitude and coefficient of the MEP variation were recorded and compared with the values obtained during the control task. We also determined the experimental time under each condition and verified whether it was within the predicted time.
RESULTS: The coefficient of variation of MEP amplitude decreased in 5 of the 7 participants, and significant differences (P=.02) were confirmed in 2 of the participants according to an F test. The coefficient of variation of the experimental time required for each stimulus after threshold modification was less than that without threshold modification, and a significant difference (P<.001) was confirmed by performing an F test.
CONCLUSIONS: We found that MEP could be suppressed using the system developed in this study and that the TMS trigger system could also stabilize the experimental time by changing the triggering threshold automatically.
摘要：
背景：经颅磁刺激（TMS），当应用于初级运动皮层时，在从外周肌肉测量的肌电图中引发运动诱发电位（MEP）。经常观察到MEP振幅在试验之间波动，即使有持续的刺激。许多因素导致TMS中的MEP波动。其中一个主要因素是大脑皮层活动的平稳性和不稳定性弱,我们假设MEP波动源于此。我们假设，当在头皮上测得的几个脑电图（EEG）通道在频域中高度相似时，将TMS传递到初级运动皮层时，MEP波动受到抑制。
目的：我们开发了一种TMS触发系统，使用EEG相干分析来抑制MEP波动，在频域中检测2个通道之间的脑电信号相似性。
方法：七个健康的成年人参加了实验，以确认TMS触发系统是否能够正常工作，记录MEP变化的平均幅度和系数，并与控制任务期间获得的值进行比较。我们还确定了每种条件下的实验时间，并验证了它是否在预测时间内。
结果：7名参与者中有5名MEP振幅的变异系数下降，根据F检验，在2名参与者中确认了显着差异（P=.02）。阈值修改后每个刺激所需的实验时间的变异系数小于不进行阈值修改时的变异系数。并且通过进行F检验证实了显着差异（P<.001）。
结论：我们发现使用本研究中开发的系统可以抑制MEP，并且TMS触发系统还可以通过自动改变触发阈值来稳定实验时间。
目的：我们开发了一种TMS触发系统，使用EEG相干分析来抑制MEP波动，在频域中检测2个通道之间的脑电信号相似性。
方法：七个健康的成年人参加了实验，以确认TMS触发系统是否能够正常工作，记录MEP变化的平均幅度和系数，并与控制任务期间获得的值进行比较。我们还确定了每种条件下的实验时间，并验证了它是否在预测时间内。
结果：7名参与者中有5名MEP振幅的变异系数下降，根据F检验，在2名参与者中确认了显着差异（P=.02）。阈值修改后每个刺激所需的实验时间的变异系数小于不进行阈值修改时的变异系数。并且通过进行F检验证实了显着差异（P<.001）。
结论：我们发现使用本研究中开发的系统可以抑制MEP，并且TMS触发系统还可以通过自动改变触发阈值来稳定实验时间。
