Nikolov Petyo, Hassan Shady S, Schnitzler Alfons, Groiss Stefan J
Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
Front Neurosci. 2021 Apr 23;15:665258. doi: 10.3389/fnins.2021.665258. eCollection 2021.
Motor evoked potentials (MEP), obtained by transcranial magnetic stimulation (TMS) are a common tool in clinical research and diagnostic. Nevertheless, reports regarding the influence of filter settings on MEP are sparse. Here, we compared MEP amplitudes and signal to noise ratio (SNR) using multiple high pass filter (HPF) and notch filter settings.
Twenty healthy subjects were enrolled in the study. Recruitment curves were obtained with HPF settings varied at 10, 20, 50, and 100 Hz. The four HPF settings were tested both with and without 50 Hz active notch filter. Low pass filter was kept constant at 5 kHz.
MEP amplitudes with HPF at 10 and 20 Hz were significantly higher than at 100 Hz, regardless of the notch filter. However, SNR did not differ among HPF settings. An active notch filter significantly improved SNR.
The reduction in MEP amplitudes with HPF above 20 Hz may be due to noise reduction, since the different HPF conditions did not alter SNR. Thus, higher HPF above 50 Hz may be an option to reduce noise, the use of a notch filter may even improve SNR.
Our findings are relevant for the selection of filter settings and might be of importance to any researcher who utilizes TMS-MEP.
经颅磁刺激（TMS）获得的运动诱发电位（MEP）是临床研究和诊断中的常用工具。然而，关于滤波设置对MEP影响的报道却很少。在此，我们使用多种高通滤波器（HPF）和陷波滤波器设置比较了MEP的振幅和信噪比（SNR）。
20名健康受试者参与了本研究。在高通滤波器设置分别为10、20、50和100赫兹的情况下获取募集曲线。这四种高通滤波器设置在有和没有50赫兹有源陷波滤波器的情况下都进行了测试。低通滤波器保持在5千赫兹不变。
无论是否有陷波滤波器，高通滤波器设置为10和20赫兹时的MEP振幅均显著高于100赫兹时的。然而，高通滤波器设置之间的信噪比并无差异。有源陷波滤波器显著提高了信噪比。
20赫兹以上高通滤波器导致MEP振幅降低可能是由于噪声减少，因为不同的高通滤波器条件并未改变信噪比。因此，50赫兹以上更高的高通滤波器设置可能是降低噪声的一种选择，使用陷波滤波器甚至可能提高信噪比。
我们的研究结果与滤波设置的选择相关，可能对任何使用TMS-MEP的研究人员都很重要。
