Verstynen T, Spencer R, Stinear C M, Konkle T, Diedrichsen J, Byblow W D, Ivry R B
Department of Psychology, University of California, Berkeley, CA 94720, USA.
Neuropsychologia. 2007 Mar 2;45(4):844-52. doi: 10.1016/j.neuropsychologia.2006.08.019. Epub 2006 Oct 4.
Congenital mirror movements (CMMs) are involuntary, symmetric movements of one hand during the production of voluntary movements with the other. CMMs have been attributed to a range of physiological mechanisms, including excessive ipsilateral projections from each motor cortex to distal extremities. We examined this hypothesis with an individual showing pronounced CMMs. Mirror movements were characterized for a set of hand muscles during a simple contraction task. Transcranial magnetic stimulation (TMS) was then used to map the relative input to each muscle from both motor cortices. Contrary to our expectations, CMMs were most prominent for muscles with the strongest contralateral representation rather than in muscles that were activated by stimulation of either hemisphere. These findings support a bilateral control hypothesis whereby CMMs result from the recruitment of both motor cortices during intended unimanual movements. Consistent with this hypothesis, bilateral motor cortex activity was evident during intended unimanual movements in an fMRI study. To assess the level at which bilateral recruitment occurs, motor cortex excitability during imagined unimanual movements was assessed with TMS. Facilitory excitation was only observed in the contralateral motor cortex. Thus, the bilateral recruitment of the hemispheres for unilateral actions in individuals with CMMs appears to occur during movement execution rather than motor planning.
先天性镜像运动（CMMs）是指在一侧手进行自主运动时，另一侧手出现的非自主对称运动。CMMs被认为与一系列生理机制有关，包括每个运动皮层向远端肢体的同侧投射过多。我们对一名表现出明显CMMs的个体进行了研究，以验证这一假设。在一项简单的收缩任务中，对一组手部肌肉的镜像运动进行了特征描述。然后使用经颅磁刺激（TMS）来绘制两个运动皮层对每块肌肉的相对输入情况。与我们的预期相反，CMMs在对侧代表最强的肌肉中最为明显，而不是在受到任何一个半球刺激而激活的肌肉中。这些发现支持了双侧控制假说，即CMMs是在预期的单手运动过程中两个运动皮层均被激活所致。与该假说一致，在一项功能磁共振成像（fMRI）研究中，预期的单手运动过程中双侧运动皮层活动明显。为了评估双侧激活发生的水平，使用TMS评估了想象中的单手运动过程中运动皮层的兴奋性。仅在对侧运动皮层观察到促进性兴奋。因此，患有CMMs的个体在单侧动作时半球的双侧激活似乎发生在运动执行过程中，而非运动计划阶段。
