Brain Imaging and Neurostimulation Laboratory, University Medical Center Hamburg-Eppendorf, Department of Neurology, 20246 Hamburg, Germany.
J Neurosci. 2011 Jun 22;31(25):9111-7. doi: 10.1523/JNEUROSCI.0046-11.2011.
Independent use of both hands is characteristic of human action in daily life. By nature, however, in-phase bimanual movements, for example clapping, are easier to accomplish than anti-phase movements, for example playing the piano. It is commonly agreed that interhemispheric interactions play a central role in the coordination of bimanual movements. However, the spatial, temporal, and physiological properties of the interhemispheric signals that coordinate different modes of bimanual movements are still not completely understood. More precisely, do individual interhemispheric connectivity parameters have behavioral relevance for bimanual rapid anti-phase coordination? To address this question, we measured movement-related interhemispheric interactions, i.e., inhibition and facilitation, and correlated them with the performance during bimanual coordination. We found that movement-related facilitation from right premotor to left primary motor cortex (rPMd-lM1) predicted performance in anti-phase bimanual movements. It is of note that only fast facilitation during the preparatory period of a movement was associated with success in anti-phase movements. Modulation of right to left primary motor interaction (rM1-lM1) was not related to anti-phase but predicted bimanual in-phase and unimanual behavior. These data suggest that strictly timed modulation of interhemispheric rPMd-lM1 connectivity is essential for independent high-frequency use of both hands. The rM1-lM1 results indicate that adjustment of connectivity between homologous M1 may be important for the regulation of homologous muscle synergies.
双手独立使用是人类日常生活中行动的特征。然而，从本质上讲，同相双手运动（例如拍手）比异相运动（例如弹钢琴）更容易完成。人们普遍认为，大脑两半球之间的相互作用在双手运动的协调中起着核心作用。然而，协调不同模式的双手运动的大脑两半球信号的空间、时间和生理特性尚不完全清楚。更确切地说，个体大脑两半球间连通性参数对于双手快速异相协调是否具有行为相关性？为了解决这个问题，我们测量了与运动相关的大脑两半球间相互作用，即抑制和易化，并将其与双手协调时的表现相关联。我们发现，来自右侧运动前区到左侧初级运动皮层的运动相关易化（rPMd-lM1）可预测双手异相运动的表现。值得注意的是，只有在运动准备期快速的易化与异相运动的成功相关。右向左初级运动相互作用（rM1-lM1）的调制与异相运动但预测双手同相和单手运动有关。这些数据表明，大脑两半球间 rPMd-lM1 连通性的严格定时调制对于双手独立高频使用至关重要。rM1-lM1 的结果表明，调节同源 M1 之间的连通性对于同源肌肉协同作用的调节可能很重要。
