Sharma Nikhil, Baron Jean-Claude, Rowe James B
Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
Ann Neurol. 2009 Nov;66(5):604-16. doi: 10.1002/ana.21810.
Neuroplasticity is essential for recovery after stroke and is the target for new stroke therapies. During recovery from subcortical motor stroke, brain activations associated with movement may appear normal despite residual functional impairment. This raises an important question: how far does recovery of motor performance depend on the processes that precede movement execution involving the premotor and prefrontal cortex, rather than recovery of the corticospinal system alone?
We examined stroke patients with functional magnetic resonance imaging while they either imagined or executed a finger-thumb opposition sequence. In addition to classical analyses of regional activations, we studied neuroplasticity in terms of differential network connectivity using structural equation modeling. The study included 8 right-handed patients who had suffered a left-hemisphere subcortical ischemic stroke with paresis, and 13 age-matched healthy controls.
With good functional recovery, the regional activations had returned to normal in patients. However, connectivity within the extended motor network remained abnormal. These abnormalities were seen predominantly during motor imagery and correlated with motor performance.
Our results indicate that neuroplasticity can manifest itself as differences in connectivity among cortical areas remote from the infarct, rather than in the degree of regional activation. Connection strengths between nodes of the cortical motor network correlate with motor outcome. The altered organization of connectivity of the prefrontal areas may reflect the role of the prefrontal cortex in higher order planning of movement. Our results are relevant to the assessment and understanding of emerging physical and neurophysiological therapies for stroke rehabilitation.
神经可塑性对中风后的恢复至关重要，且是新型中风治疗方法的目标。在从皮质下运动性中风恢复的过程中，尽管存在残余功能障碍，但与运动相关的脑激活可能看起来正常。这就引出了一个重要问题：运动表现的恢复在多大程度上取决于运动执行之前涉及运动前区和前额叶皮质的过程，而不仅仅是皮质脊髓系统的恢复？
我们对中风患者进行功能磁共振成像检查，让他们想象或执行拇指对指序列。除了对区域激活进行经典分析外，我们还使用结构方程模型从差异网络连通性方面研究神经可塑性。该研究包括8名患有左半球皮质下缺血性中风并伴有轻瘫的右利手患者，以及13名年龄匹配的健康对照者。
随着功能的良好恢复，患者的区域激活已恢复正常。然而，扩展运动网络内的连通性仍然异常。这些异常主要在运动想象期间出现，并且与运动表现相关。
我们的结果表明，神经可塑性可表现为远离梗死灶的皮质区域之间连通性的差异，而非区域激活程度的差异。皮质运动网络节点之间的连接强度与运动结果相关。前额叶区域连通性的改变组织可能反映了前额叶皮质在运动的高级规划中的作用。我们的结果与中风康复新兴物理和神经生理治疗方法的评估及理解相关。
