Nuyts Marten, Verstraelen Stefanie, Frieske Joana, Meesen Raf, Hoornweder Sybren Van
REVAL - Rehabilitation Research Center, Faculty of Rehabilitation Sciences, University of Hasselt, Diepenbeek, Belgium.
REVAL - Rehabilitation Research Center, Faculty of Rehabilitation Sciences, University of Hasselt, Diepenbeek, Belgium.
Clin Neurophysiol. 2025 Feb;170:123-131. doi: 10.1016/j.clinph.2024.12.009. Epub 2024 Dec 14.
Corticospinal excitability can be quantified using motor-evoked potentials (MEP) following transcranial magnetic stimulation (TMS). However, the inherent variability of MEPs poses significant challenges. We establish a framework using personal and experimental factors to select the optimal number of trials (n) required for reliable MEP estimates.
47 healthy younger underwent single-pulse TMS over the left primary motor cortex (M1). Per participant, 550 MEPs were collected at intensities ranging from 110 % to 150 % of the resting motor threshold (rMT), in 10 % increments. Per intensity, we calculated n. We analyzed which personal and experimental factors affected n.
n decreased with increasing TMS intensity, lower rMT baseline values, and exclusion of single-trial outliers. Sex had no significant effect.
Our study indicates that even when TMS is used as an outcome measure, custom-tailoring its protocol to study-related circumstances is key, as TMS intensity, outliers, baseline rMT, and the desired precision level affect the number of TMS trials needed to obtain a reliable MEP. Thus, we underscore the absence of a universal rule-of-thumb rule, although our predictive equations and online tool provide future TMS experimenters with the means to estimate the required number of TMS trials based on individual characteristics and specific experimental conditions.
Our predictive equations offer a tailored approach for selecting n, enhancing the reliability of TMS-derived corticospinal excitability measurements.
经颅磁刺激（TMS）后，可通过运动诱发电位（MEP）对皮质脊髓兴奋性进行量化。然而，MEP固有的变异性带来了重大挑战。我们建立了一个框架，利用个人因素和实验因素来选择可靠估计MEP所需的最佳试验次数（n）。
47名健康年轻人在左侧初级运动皮层（M1）接受单脉冲TMS。每位参与者在静息运动阈值（rMT）的110%至150%范围内，以10%的增量收集550个MEP，每次强度下计算n。我们分析了哪些个人因素和实验因素会影响n。
n随着TMS强度的增加、rMT基线值的降低以及单次试验异常值的排除而减少。性别无显著影响。
我们的研究表明，即使将TMS用作结果指标，根据研究相关情况定制其方案也很关键，因为TMS强度、异常值、基线rMT以及所需的精度水平会影响获得可靠MEP所需的TMS试验次数。因此，我们强调不存在通用的经验法则，尽管我们的预测方程和在线工具为未来的TMS实验者提供了根据个体特征和特定实验条件估计所需TMS试验次数的方法。
我们的预测方程为选择n提供了一种定制方法，提高了TMS衍生的皮质脊髓兴奋性测量的可靠性。
