de Albuquerque Lidio Lima, Pantovic Milan, Wilkins Erik W, Morris Desiree, Clingo Mitchell, Boss Sage, Riley Zachary A, Poston Brach
School of Health and Applied Human Sciences, University of North Carolina Wilmington, Wilmington, NC 28403, USA.
Health and Human Performance Department, Utah Tech University, St. George, UT 84770, USA.
Bioengineering (Basel). 2024 Jun 25;11(7):645. doi: 10.3390/bioengineering11070645.
Short-interval intracortical inhibition (SICI) is a common paired-pulse transcranial magnetic stimulation (TMS) measure used to assess primary motor cortex (M1) interneuron activity in healthy populations and in neurological disorders. Many of the parameters of TMS stimulation to most accurately measure SICI have been determined. However, one TMS parameter that has not been investigated is the time between SICI trials (termed inter-trial interval; ITI). This is despite a series of single-pulse TMS studies which have reported that motor evoked potential (MEP) amplitude were suppressed for short, but not long ITIs in approximately the initial ten trials of a TMS block of 20-30 trials. The primary purpose was to examine the effects of ITI on the quantification of SICI at rest. A total of 23 healthy adults completed an experimental session that included four SICI trial blocks. Each block utilized a different ITI (4, 6, 8, and 10 s) and was comprised of a total of 26 SICI trials divided into three epochs. ANOVA revealed that the main effects for ITI and epoch as well as their interaction were all non-statistically significant for SICI. We conclude that the shorter (4-6 s) ITIs used in studies investigating SICI should not alter the interpretation of M1 activity, while having the advantages of being more comfortable to participants and reducing the experimental time needed to evaluate perform single and paired-pulse TMS experiments.
短间隔皮质内抑制（SICI）是一种常见的双脉冲经颅磁刺激（TMS）测量方法，用于评估健康人群和神经疾病患者的初级运动皮层（M1）中间神经元活动。已经确定了TMS刺激的许多参数，以最准确地测量SICI。然而，一个尚未研究的TMS参数是SICI试验之间的时间（称为试验间隔时间；ITI）。尽管有一系列单脉冲TMS研究报告称，在20-30次试验的TMS组块的大约最初十次试验中，运动诱发电位（MEP）幅度在短ITI时被抑制，但在长ITI时未被抑制。主要目的是研究ITI对静息状态下SICI量化的影响。共有23名健康成年人完成了一个实验环节，其中包括四个SICI试验组块。每个组块使用不同的ITI（4、6、8和10秒），总共由26次SICI试验组成，分为三个时段。方差分析显示，ITI和时段的主效应以及它们的交互作用对SICI均无统计学意义。我们得出结论，在研究SICI的研究中使用较短（4-6秒）的ITI不应改变对M1活动的解释，同时具有让参与者更舒适以及减少评估单脉冲和双脉冲TMS实验所需实验时间的优点。
