Motor Control Laboratory, Research Centre for Motor Control and Neuroplasticity, Department of Biomedical Kinesiology, Group Biomedical Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.
PLoS One. 2011 Mar 9;6(3):e17742. doi: 10.1371/journal.pone.0017742.
Unilateral movements are mainly controlled by the contralateral hemisphere, even though the primary motor cortex ipsilateral (M1(ipsi)) to the moving body side can undergo task-related changes of activity as well. Here we used transcranial magnetic stimulation (TMS) to investigate whether representations of the wrist flexor (FCR) and extensor (ECR) in M1(ipsi) would be modulated when unilateral rhythmical wrist movements were executed in isolation or in the context of a simple or difficult hand-foot coordination pattern, and whether this modulation would differ for the left versus right hemisphere. We found that M1(ipsi) facilitation of the resting ECR and FCR mirrored the activation of the moving wrist such that facilitation was higher when the homologous muscle was activated during the cyclical movement. We showed that this ipsilateral facilitation increased significantly when the wrist movements were performed in the context of demanding hand-foot coordination tasks whereas foot movements alone influenced the hand representation of M1(ipsi) only slightly. Our data revealed a clear hemispheric asymmetry such that MEP responses were significantly larger when elicited in the left M1(ipsi) than in the right. In experiment 2, we tested whether the modulations of M1(ipsi) facilitation, caused by performing different coordination tasks with the left versus right body sides, could be explained by changes in short intracortical inhibition (SICI). We found that SICI was increasingly reduced for a complex coordination pattern as compared to rest, but only in the right M1(ipsi). We argue that our results might reflect the stronger involvement of the left versus right hemisphere in performing demanding motor tasks.
单侧运动主要由对侧半球控制，尽管同侧（M1（ipsi））初级运动皮层也可以发生与任务相关的活动变化。在这里，我们使用经颅磁刺激（TMS）来研究当单侧节律性手腕运动在孤立或简单或困难的手脚协调模式下执行时，M1（ipsi）中手腕屈肌（FCR）和伸肌（ECR）的代表是否会发生调制，以及这种调制是否会因左半球和右半球而有所不同。我们发现，M1（ipsi）对静息 ECR 和 FCR 的易化与运动手腕的激活相匹配，即当同源肌肉在周期性运动中被激活时，易化程度更高。我们表明，当手腕运动在要求较高的手脚协调任务中进行时，这种同侧易化会显著增加，而单独的脚部运动只会对 M1（ipsi）的手部代表产生轻微影响。我们的数据显示出明显的半球不对称性，即当在左侧 M1（ipsi）中诱发时，MEP 反应明显大于右侧。在实验 2 中，我们测试了通过用左侧和右侧身体执行不同的协调任务来调节 M1（ipsi）易化的情况，是否可以通过短程皮质内抑制（SICI）的变化来解释。我们发现，与休息相比，对于复杂的协调模式，SICI 会逐渐减少，但仅在右侧 M1（ipsi）中。我们认为，我们的结果可能反映了左半球和右半球在执行高要求运动任务时的更强参与。
