Department of Psychology and University of Arizona, Tucson, Arizona, USA.
Department of Biomedical Engineering, University of Arizona, Tucson, Arizona, USA.
Brain Connect. 2023 Feb;13(1):39-50. doi: 10.1089/brain.2021.0180. Epub 2022 Jun 27.
Repetitive transcranial magnetic stimulation (rTMS) is a promising therapeutic technique, and is believed to accomplish its effect by influencing the stimulated and remotely connected areas. However, responsiveness to rTMS shows high interindividual variability, and this intersubject variability is particularly high in older adults. It remains unclear whether baseline resting-state functional connectivity (rsFC) contributes to this variability in older adults. The aims of this study are to (1) examine rTMS effects over the primary motor cortex (M1) in older adults, and (2) identify baseline network properties that may contribute to the interindividual variability. We tested response to intermittent theta burst stimulation (iTBS), an effective rTMS protocol, over M1 by using both electromyography and resting-state functional magnetic resonance imaging in older adults. Outcome measures included motor-evoked potential (MEP) elicited by single-pulse transcranial magnetic stimulation and rsFC before and after an iTBS session. iTBS significantly increased MEP amplitudes and rsFC between the stimulation site, sensorimotor cortex, and supplementary motor area (SMA) in older adults. iTBS-induced changes in MEP amplitude were positively correlated with increases in interhemispheric rsFC after iTBS. Furthermore, older adults with lower baseline interhemispheric rsFC between sensorimotor cortex and SMA exhibited stronger MEP response after iTBS. Findings of the study suggest that different levels of interhemispheric communication during resting state might contribute to the response heterogeneity to iTBS in older adults. Interhemispheric rsFC may have great potential serving as a useful marker for predicting iTBS responsiveness in older adults. ClinicalTrials.gov ID: 1707654427 Impact statement Factors contributing to interindividual variability of the responsive to repetitive transcranial magnetic stimulation (rTMS) in older adults remain poorly understood. In this study, we examined the effects of rTMS over the primary motor cortex in older adults, and found that response to rTMS is associated with prestimulation interhemispheric connectivity in the sensorimotor and premotor areas. Findings of the study have great potential to be translated into a connectivity-based strategy for identification of responders for rTMS in older adults.
重复经颅磁刺激 (rTMS) 是一种很有前途的治疗技术，据信它通过影响刺激和远程连接的区域来发挥作用。然而，rTMS 的反应在个体间表现出高度的可变性，而这种个体间的可变性在老年人中尤其高。目前尚不清楚静息状态功能连接 (rsFC) 是否有助于老年人的这种变异性。本研究的目的是：(1) 检测 rTMS 对老年人初级运动皮层 (M1) 的影响；(2) 确定可能导致个体间变异性的基线网络特性。我们使用肌电图和静息态功能磁共振成像测试了老年人 M1 上的间歇性 theta 爆发刺激 (iTBS) 的反应，这是一种有效的 rTMS 方案。结果测量包括单次经颅磁刺激诱发的运动诱发电位 (MEP) 和 iTBS 前后的 rsFC。iTBS 显著增加了老年人 MEP 幅度和刺激部位、感觉运动皮层和辅助运动区 (SMA) 之间的 rsFC。iTBS 诱导的 MEP 幅度变化与 iTBS 后双侧半球 rsFC 的增加呈正相关。此外，在 iTBS 后，基底 rsFC 较低的老年人的 MEP 反应更强。该研究的结果表明，静息状态下不同水平的半球间通讯可能导致老年人对 iTBS 的反应异质性。半球间 rsFC 可能具有作为预测老年人 iTBS 反应性的有用标志物的巨大潜力。ClinicalTrials.gov ID：1707654427 影响陈述 导致老年人对重复经颅磁刺激 (rTMS) 反应性个体间差异的因素仍知之甚少。在这项研究中，我们研究了 rTMS 对老年人初级运动皮层的影响，发现 rTMS 的反应与刺激前感觉运动和运动前区域的半球间连接有关。该研究的结果具有很大的潜力转化为一种基于连接的策略，用于识别老年人 rTMS 的反应者。
