BACKGROUND Studies examining the contribution of contralesional brain regions to motor recovery after stroke have revealed conflicting results comprising both supporting and disturbing influences. Especially the relevance of contralesional brain regions beyond primary motor cortex (M1) has rarely been studied, particularly concerning the temporal dynamics post-stroke. METHODS We, therefore, used online transcranial magnetic stimulation (TMS) interference to longitudinally assess the role of contralesional (right) frontoparietal areas for recovery of hand motor function after left hemispheric stroke: contralesional M1, contralesional dorsal premotor cortex (dPMC), and contralesional anterior intraparietal sulcus (IPS). Fourteen stroke patients and sixteen age-matched healthy subjects performed motor tasks of varying complexity with their (paretic) right hand. Motor performance was quantified using three-dimensional kinematic data. All patients were assessed twice, (i) in the first week, and (ii) after more than three months post-stroke. RESULTS While we did not observe a significant effect of TMS interference on movement kinematics following the stimulation of contralesional M1 and dPMC in the first week post-stroke, we found improvements of motor performance upon interference with contralesional IPS across motor tasks early after stroke, an effect that persisted into the later phase. By contrast, for dPMC, TMS-induced deterioration of motor performance was only evident three months post-stroke, suggesting that a supportive role of contralesional premotor cortex might evolve with reorganization. CONCLUSION We here highlight time-sensitive and region-specific effects of contralesional frontoparietal areas after left hemisphere stroke, which may influence on neuromodulation regimes aiming at supporting recovery of motor function post-stroke.

中文翻译：

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对侧额顶区在脑卒中后皮质重组中的不同作用

背景研究检查对侧脑区对中风后运动恢复的贡献的研究揭示了相互矛盾的结果，包括支持和干扰影响。特别是初级运动皮层 (M1) 以外的对侧大脑区域的相关性很少被研究，特别是关于中风后的时间动态。因此，我们使用在线经颅磁刺激 (TMS) 干扰纵向评估对侧（右）额顶区在左半球卒中后手部运动功能恢复中的作用：对侧 M1、对侧背侧运动前皮层 (dPMC) 和对侧运动前皮层 (dPMC)前顶内沟 (IPS)。14 名中风患者和 16 名年龄匹配的健康受试者用（麻痹的）右手执行不同复杂性的运动任务。使用三维运动学数据量化运动性能。所有患者都接受了两次评估，(i) 在第一周，和 (ii) 在中风后三个月以上。结果 虽然在中风后第一周刺激对侧 M1 和 dPMC 后，我们没有观察到 TMS 干扰对运动运动学的显着影响，但我们发现在中风后早期通过运动任务干扰对侧 IPS 后，运动性能得到改善，效果一直延续到后期。相比之下，对于 dPMC，TMS 引起的运动性能恶化仅在中风后三个月才明显，表明对侧运动前皮层的支持作用可能会随着重组而发展。结论 我们在此强调左半球中风后对侧额顶区的时间敏感性和区域特异性影响，这可能会影响旨在支持中风后运动功能恢复的神经调节机制。