Cortical control of a proximo-distal muscle synergy in humans

美国神经学家和科学作家Richard E Cytowic在他的《品尝形状的人》一书中描述说，大脑是一个“分布式系统”，其中“特定回路所服务的复杂功能的许多方面并不严格地位于其任何一个部分，而是在任何给定时间发生在回路本身的主导过程中”。因此，这里描述的实验研究旨在进一步了解人类大脑的这一主导过程是怎样的，更确切地说，它是如何为肌肉协调和协同作用而工作的。这是一个控制关节间运动（协同）的大脑功能连接的问题，目前的资助扩大了对这种控制的发育方面的关注。此外，这项基础工作将对拓宽我们对成人损伤或学龄儿童早产史后大脑连接相关的重组（可塑性）潜力的认识具有重要意义。为此目的，健康的成年人和足月出生的健康学龄儿童（8-10岁）将参加。该实验将测试大脑结构内部以及大脑和小脑之间的连接是否参与了近端-远端肌肉协同作用的控制。我们所使用的实验模型是一个精确的握持任务，其中叠加了周期性的手腕运动。将应用经颅磁刺激（TMS）的标准化范式（单脉冲、双脉冲、重复）来测试成人和儿童大脑连接的功能性存在。图像引导的TMS导航仪将用于精确的大脑和小脑刺激。将测试手腕运动的主动与被动情况或肌肉振动引起的手腕运动幻觉。结果可能对神经康复有潜在的影响，为卒中患者和患有肌肉协调障碍的早产儿促进手远端功能提供新的指导。

The American neurologist and science writer Richard E Cytowic described in his book titled 'The man who tasted shapes', that the brain was as a "distributed system" where "the many aspects of complex functions subserved by a particular circuit are not rigidly located in any one of its segments but rather in the dominant process occurring at any given time in the circuit itself". The experimental studies described here are thus aimed at understanding further how this dominant process of human brain is like and more precisely, how it works for muscle coordination and synergy. It is question of brain functional connectivity to control interjoint movement (synergy) and the current grant enlarges the focus on the developmental aspect of such a control. Besides, this basic work will be of major importance to broaden our knowledge of the brain connectivity - related potential of reorganization (plasticity) following a lesion in adults or due to a preterm birth history in school-aged children. To this end, healthy adults and healthy school-aged (8-10 yr) children born full-term will participate. The experiments will test whether connections within brain structures and between brain and cerebellum are involved in the control of a proximo-distal muscle synergy. The experimental model we are used to work with is namely a precision grip task with superimposed cyclic wrist movements. Standardized paradigms of transcranial magnetic stimulation (TMS) will be applied (single, paired-pulse, repetitive) to test the functional existence of cerebral connections in adults and children. An image-guided TMS navigator will be used for accurate brain and cerebellum stimulation. Active vs. passive conditions of wrist movements or illusion of wrist movements induced by muscle vibration will be tested. Results may have a potential impact in neuro-rehabilitation to provide new guidelines for promoting hand distal function in patients with stroke and in very preterm children living with muscle coordination impairments.