McKiernan B J, Marcario J K, Karrer J H, Cheney P D
Department of Molecular and Integrative Physiology, and Smith Mental Retardation and Human Development Research Center, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
J Neurophysiol. 1998 Oct;80(4):1961-80. doi: 10.1152/jn.1998.80.4.1961.
We used spike-triggered averaging of rectified electromyographic activity to determine whether corticomotoneuronal (CM) cells produce postspike effects in muscles of both proximal and distal forelimb joints in monkeys performing a reach and prehension task. Two monkeys were trained to perform a self-paced task in which they reached forward from a starting position to retrieve a food reward from a small cylindrical well. We compiled spike-triggered averages from 22 to 24 separate forelimb muscles at both proximal (shoulder, elbow) and distal (wrist, digits, intrinsic hand) joints. Of 174 cells examined, 112 produced postspike effects in at least one of the target muscles. Of those cells, 45.5% produced postspike effects in both proximal and distal forelimb muscles. A nearly equal number (44.7%) produced postspike effects in distal muscles only, whereas a clear minority (9.8%) produced postspike effects in only proximal muscles. The majority of CM cells (71.4%) produced effects in two or more muscles, with an average muscle field of 3.1 +/- 2.1 (mean +/- SD) for facilitation plus suppression. Of 345 postspike effects identified, 70.7% were facilitation effects and 29.3% were suppression effects. The large majority of effects (72.2%) were in distal muscles. When averaged by joint, the latency and peak magnitude of postspike facilitation showed a stepwise increase from proximal to distal joints. The results of this study show that the majority of CM cells engaged in coordinated forelimb reaching movements facilitate and/or suppress muscles at multiple joints, including muscles at both proximal and distal joints. The results also show that CM cells make more frequent and more potent terminations in motoneuron pools of distal compared with proximal muscles.
我们利用整流后的肌电图活动进行触发脉冲平均，以确定在执行伸手抓握任务的猴子中，皮质脊髓运动神经元（CM）细胞是否会在前肢近端和远端关节的肌肉中产生脉冲后效应。训练了两只猴子执行一项自主节奏任务，即从起始位置向前伸手，从小圆柱形孔中获取食物奖励。我们汇总了来自近端（肩部、肘部）和远端（腕部、手指、手部固有肌）关节处22至24块不同前肢肌肉的触发脉冲平均值。在检查的174个细胞中，有112个在至少一块目标肌肉中产生了脉冲后效应。在这些细胞中，45.5%在近端和远端前肢肌肉中都产生了脉冲后效应。几乎相同数量（44.7%）的细胞仅在远端肌肉中产生脉冲后效应，而明显少数（9.8%）的细胞仅在近端肌肉中产生脉冲后效应。大多数CM细胞（71.4%）在两块或更多肌肉中产生效应，促进加抑制的平均肌肉场为3.1±2.1（平均值±标准差）。在识别出的345个脉冲后效应中，70.7%是促进效应，29.3%是抑制效应。绝大多数效应（72.2%）出现在远端肌肉中。按关节平均时，脉冲后促进的潜伏期和峰值幅度从近端关节到远端关节呈逐步增加。本研究结果表明，参与前肢协调伸展运动的大多数CM细胞会促进和/或抑制多个关节的肌肉，包括近端和远端关节的肌肉。结果还表明，与近端肌肉相比，CM细胞在远端运动神经元池中的终止更频繁、更有效。
