Motor cortex excitability and connectivity in chronic stroke: a multimodal model of functional reorganization
Motor cortex excitability and connectivity in chronic stroke: a multimodal model of functional reorganization
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DOI：
10.1007/s00429-013-0702-8
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发表时间：
2015-03-01
影响因子：
3.1
通讯作者：
Grefkes, Christian
中科院分区：
文献类型：
--
作者：
Volz, Lukas J.;Sarfeld, Anna-Sophia;Grefkes, Christian
脑缺血会引发一系列细胞过程，从而诱导神经保护、炎症、细胞凋亡和再生。在神经网络水平上，损伤同时诱发大脑可塑性。然而，许多中风幸存者留下了永久性的运动缺陷，并且对决定中风后功能结果的神经生物学因素知之甚少。经颅磁刺激 (TMS) 和磁共振成像 (MRI) 是非侵入性方法，可以深入了解皮质运动系统的功能（重新）组织。我们在这里结合神经导航 TMS、MRI 和连接分析来研究手功能恢复的程度取决于皮质脊髓束 (CST) 损伤和大脑可塑性的生物标志物，如皮质兴奋性和运动网络有效连接。正如预期的那样，12 名患有持续性运动缺陷的中风患者的个人运动表现被发现不仅取决于 CST 损伤的程度，还取决于运动皮层的兴奋性和半球间的连接性。此外，数据显示，严重受损患者的同侧运动皮层兴奋性降低与半球间抑制降低之间存在很强的相关性。同侧运动皮层兴奋性的个体间差异与运动缺陷的相关性比异常半球间连接或 CST 损伤的相关性更强。结合这三个因素的多元线性回归分析解释了功能障碍80%以上的方差。皮质兴奋性和半球间抑制减少的相互关系为中风后对侧半球的抑制解除理论提供了直接的多模态证据。最后，我们的数据揭示了一个关键机制（即与兴奋性相关的半球间抑制减少），解释了旨在调节中风患者皮质兴奋性的新型治疗方法的康复潜力。
Cerebral ischemia triggers a cascade of cellular processes, which induce neuroprotection, inflammation, apoptosis and regeneration. At the neural network level, lesions concomitantly induce cerebral plasticity. Yet, many stroke survivors are left with a permanent motor deficit, and only little is known about the neurobiological factors that determine functional outcome after stroke. Transcranial magnetic stimulation (TMS) and magnetic resonance imaging (MRI) are non-invasive approaches that allow insights into the functional (re-) organization of the cortical motor system. We here combined neuronavigated TMS, MRI and analyses of connectivity to investigate to which degree recovery of hand function depends on corticospinal tract (CST) damage and biomarkers of cerebral plasticity like cortical excitability and motor network effective connectivity. As expected, individual motor performance of 12 stroke patients with persistent motor deficits was found to depend upon the degree of CST damage but also motor cortex excitability and interhemispheric connectivity. In addition, the data revealed a strong correlation between reduced ipsilesional motor cortex excitability and reduced interhemispheric inhibition in severely impaired patients. Interindividual differences in ipsilesional motor cortex excitability were stronger related to the motor deficit than abnormal interhemispheric connectivity or CST damage. Multivariate linear regression analysis combining the three factors accounted for more than 80 % of the variance in functional impairment. The inter-relation of cortical excitability and reduced interhemispheric inhibition provides direct multi-modal evidence for the disinhibition theory of the contralesional hemisphere following stroke. Finally, our data reveal a key mechanism (i.e., the excitability-related reduction in interhemispheric inhibition) accounting for the rehabilitative potential of novel therapeutic approaches which aim at modulating cortical excitability in stroke patients.