NeuroImage: Clinical Interindividual di ff erences in motor network connectivity and behavioral response to iTBS in stroke patients
NeuroImage: Clinical Interindividual di ff erences in motor network connectivity and behavioral response to iTBS in stroke patients
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一项研究表明，通过 rTMS 调节初级运动皮层 (M1) 兴奋性后，受中风影响的手部运动性能的改善表现出很高的个体差异。我们在这里测试了这样的假设：在中风患者中，兴奋性 rTMS 行为反应的个体差异与刺激区域网络连接的个体差异有关。慢性中风患者 (n = 14) 和健康对照组 (n = 12) 在执行简单的手部运动任务时接受功能磁共振成像 (fMRI) 扫描。动态因果模型（DCM）用于研究关键运动区域的有效连接。在功能磁共振成像实验后的不同天，患者接受对同侧 M1 的间歇性 theta 突发刺激 (iTBS) 或对顶枕皮质的控制刺激。在 iTBS 之前和之后测量运动性能和皮质兴奋性的 TMS 参数。我们的结果显示，在开始 iTBS 干预之前，受影响手部运动性能较好的患者在辅助运动区 (SMA) 和 M1 之间表现出更强的内源性耦合。与对照刺激相比，将 iTBS 应用于同侧 M1 显着增加同侧 M1 兴奋性并降低对侧 M1 兴奋性。 iTBS 后的个体行为改善与刺激前受刺激半球的神经耦合强度特别相关，尤其是针对受刺激 M1 的连接。结合内源连接和行为参数可以解释 iTBS 后观察到的手部运动表现差异的 82%。总之，数据表明，中风后个体对 iTBS 的易感性受到受损半球运动网络连接的个体间差异的影响。
an of suggest that improvements in motor performance of the stroke-a ff ected hand following modulation of primary motor cortex (M1) excitability by rTMS shows a high interindividual variability. We here tested the hypothesis that in stroke patients the interindividual variability of behavioral response to excitatory rTMS is related to interindividual di ff erences in network connectivity of the stimulated region. Chronic stroke patients ( n = 14) and healthy controls ( n = 12) were scanned with functional magnetic re- sonance imaging (fMRI) while performing a simple hand motor task. Dynamic causal modeling (DCM) was used to investigate e ff ective connectivity of key motor regions. On two di ff erent days after the fMRI experiment, patients received either intermittent theta-burst stimulation (iTBS) over ipsilesional M1 or control stimulation over the parieto-occipital cortex. Motor performance and TMS parameters of cortical excitability were measured before and after iTBS. Our results revealed that patients with better motor performance of the a ff ected hand showed stronger endogenous coupling between supplemental motor area (SMA) and M1 before starting the iTBS intervention. Applying iTBS to ipsilesional M1 signi fi cantly increased ipsilesional M1 excitability and decreased contralesional M1 excitability as compared to control stimulation. Individual behavioral improvements fol- lowing iTBS speci fi cally correlated with neural coupling strengths in the stimulated hemisphere prior to stimulation, especially for connections targeting the stimulated M1. Combining endogenous connectivity and behavioral parameters explained 82% of the variance in hand motor performance observed after iTBS. In conclusion, the data suggest that the individual susceptibility to iTBS after stroke is in fl uenced by interindividual di ff erences in motor network connectivity of the lesioned hemisphere.