Davare M, Duque J, Vandermeeren Y, Thonnard J-L, Olivier E
Laboratory of Neurophysiology, Department of Physiology, School of Medicine, Université catholique de Louvain, Brussels, Belgium.
Cereb Cortex. 2007 Feb;17(2):353-62. doi: 10.1093/cercor/bhj152. Epub 2006 Mar 8.
The precise contribution of the ipsilateral primary motor cortex (iM1) to hand movements remains controversial. To address this issue, we elicited transient virtual lesions of iM1 by means of transcranial magnetic stimulation (TMS) in healthy subjects performing either a grip-lift task or a step-tracking task with their right dominant hand. We found that, irrespective of the task, a virtual lesion of iM1 altered the timing of the muscle recruitment. In the grip-lift task, this led to a less coordinated sequence of grip and lift movements and in the step-tracking task, to a perturbation of the movement trajectory. In the step-tracking task, we have demonstrated that disrupting iM1 activity may, depending on the TMS delay, either advance or delay the muscle recruitment. The present study suggests that iM1 plays a critical role in hand movements by contributing to the setting of the muscle recruitment timing, most likely through either inhibitory or facilitatory transcallosal influences onto the contralateral M1 (cM1). iM1 would therefore contribute to shape precisely the muscular command originating from cM1.
同侧初级运动皮层（iM1）对手部运动的确切贡献仍存在争议。为解决这一问题，我们通过经颅磁刺激（TMS）在使用右手优势手执行抓握-提起任务或阶梯跟踪任务的健康受试者中诱发iM1的短暂虚拟损伤。我们发现，无论任务如何，iM1的虚拟损伤都会改变肌肉募集的时间。在抓握-提起任务中，这导致抓握和提起动作的协调性降低，而在阶梯跟踪任务中，则导致运动轨迹受到干扰。在阶梯跟踪任务中，我们已经证明，根据TMS延迟的不同，破坏iM1活动可能会提前或延迟肌肉募集。本研究表明，iM1通过参与肌肉募集时间的设定，最有可能通过对侧M1（cM1）的抑制性或易化性胼胝体间影响，在手部运动中发挥关键作用。因此，iM1将有助于精确塑造源自cM1的肌肉指令。
