美国哥伦比亚大学Mark M. Churchland小组的最新研究发现神经元可以灵活调控运动单元（MU）。相关论文于2022年10月10日发表在《自然—神经科学》杂志上。

研究人员建立了一个等距任务，即使在快速变化的力场中也可以稳定记录恒河猴的MU活动。令人惊讶的是，MU的活动模式依赖于行为，并且只能通过多个虚拟驱动器来准确描述。与灵活降序控制一致，邻近皮质位点的微小刺激招募了不同的MU。

此外，皮质群体反应具有充足的自由度以对细粒度控制进行潜在调控。因此，MU活动可被灵活调控以满足任务需求，皮层可能参与该调控过程。

据悉，自主运动需要从皮层到脊髓的信号传递，其中特定MU池激活每块肌肉。对MU功能的描述主要基于两个基本原则。首先，大脑皮层不能独立控制MU，而是为每个MU池提供一个公共驱动器。其次，MU的招募方式与亨尼曼大小招募原则规则大相径庭。虽然这种范式具有许多理论支持，但直接测试需要同时观察分布在不同力中的许多MU。

附：英文原文

Title: Flexible neural control of motor units

Author: Marshall, Najja J., Glaser, Joshua I., Trautmann, Eric M., Amematsro, Elom A., Perkins, Sean M., Shadlen, Michael N., Abbott, L. F., Cunningham, John P., Churchland, Mark M.

Issue&Volume: 2022-10-10

Abstract: Voluntary movement requires communication from cortex to the spinal cord, where a dedicated pool of motor units (MUs) activates each muscle. The canonical description of MU function rests upon two foundational tenets. First, cortex cannot control MUs independently but supplies each pool with a common drive. Second, MUs are recruited in a rigid fashion that largely accords with Henneman’s size principle. Although this paradigm has considerable empirical support, a direct test requires simultaneous observations of many MUs across diverse force profiles. In this study, we developed an isometric task that allowed stable MU recordings, in a rhesus macaque, even during rapidly changing forces. Patterns of MU activity were surprisingly behavior-dependent and could be accurately described only by assuming multiple drives. Consistent with flexible descending control, microstimulation of neighboring cortical sites recruited different MUs. Furthermore, the cortical population response displayed sufficient degrees of freedom to potentially exert fine-grained control. Thus, MU activity is flexibly controlled to meet task demands, and cortex may contribute to this ability.

DOI: 10.1038/s41593-022-01165-8

Source: https://www.nature.com/articles/s41593-022-01165-8