Function of spinal neural circuit for generating muscle activities

在执行精确握力任务的猴子中，我们记录了任务过程中颈脊髓的活动，同时记录了手和手臂肌肉的肌电活动。大多数Prem-ins(23/25)表现为与运动相关的放电频率调制：11块为时相后紧张性易化(p+t+)，4块为纯相，4块为纯紧张性，4块为失活，而靶肌肉持续存在p+t+活动(65/66块肌肉)。结果表明，脊髓前角蛋白参与了多条神经通路的调节，对灵长类动物精确握力的控制具有重要意义。为了检测脊髓INS介导的下行信号，我们识别了251个M1和90个红核脊髓神经元，并使用非负矩阵分解从EMG信号中提取了肌肉协同效应。对群体的PREM连接模式的聚类分析表明，每个PREM群体可以以不同的方式为肌肉协同作用提供神经元支撑。

In monkeys performing precision grip task, we recorded activity from the cervical spinal cordsimultaneously with electromyographic (EMG) activity from hand and arm muscles during the task. Most PreM-INs (23/25) displayed movement-related firing rate modulations: 11 had phasic followed by tonic facilitation (p+t+); 4 were pure phasic; 4 were pure tonic; and 4 were deactivated, while their target muscles consistently had p+t+ activity (65/66 muscles). Results indicated that several neural pathway could be mediated by the spinal PreM-INs makes a significant contribution to the control of precision grip in primates. For detecting the descending signal mediated by spinal Ins, we identified 251 M1 and 90 rubrospinal neurons, and extracted muscle synergies using non-negative matrix factorization from the EMG signals. Clustering analysis of the PreM connection patterns of the populations indicate each PreM population can provide a neuronal underpinning of muscle synergies in contrasting ways.