Muscle Coordination Is Habitual Rather than Optimal
Muscle Coordination Is Habitual Rather than Optimal
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DOI：
10.1523/jneurosci.5792-11.2012
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发表时间：
2012-05-23
影响因子：
5.3
通讯作者：
Carroll, Timothy J.
中科院分区：
文献类型：
--
作者：
de Rugy, Aymar;Loeb, Gerald E.;Carroll, Timothy J.
当在多块肌肉之间分担负荷时，人类似乎会选择一种最佳的激活模式，以最大限度地减少成本，例如运动的努力或变化性。然而，神经系统如何实现这种行为尚不清楚。在这里，我们表明，相反的最优控制理论的预测，习惯性肌肉激活模式是令人惊讶的强大的肢体生物力学的变化。我们首先开发了一种方法来模拟关节力在真实的时间从肌电图记录的手腕肌肉。当模型被改变以模拟肌肉麻痹的效果时，受试者只是增加了所有肌肉的招募来完成任务，而不是只招募有用的肌肉。当模型被改变，使一块肌肉的力量输出异常嘈杂时，受试者再次坚持招募所有肌肉，而不是消除嘈杂的肌肉。这种习惯性的协调模式也不受生物力学的真实的改变的影响，生物力学的改变是通过选择性地损伤肌肉而不影响感觉反馈而产生的。受试者自然使用不同的肌肉收缩模式，以产生相同的力量，在不同的旋前-旋后姿势，但当模拟是基于一个姿势不同于实际姿势，招聘模式往往与实际，而不是模拟姿势。结果似乎与大脑中最佳控制器对运动程序的计算不一致。相反，大脑可能会学习和回忆命令程序，导致肌肉协调模式产生的较低的感觉运动回路，功能“足够好”。"
When sharing load among multiple muscles, humans appear to select an optimal pattern of activation that minimizes costs such as the effort or variability of movement. How the nervous system achieves this behavior, however, is unknown. Here we show that contrary to predictions from optimal control theory, habitual muscle activation patterns are surprisingly robust to changes in limb biomechanics. We first developed a method to simulate joint forces in real time from electromyographic recordings of the wrist muscles. When the model was altered to simulate the effects of paralyzing a muscle, the subjects simply increased the recruitment of all muscles to accomplish the task, rather than recruiting only the useful muscles. When the model was altered to make the force output of one muscle unusually noisy, the subjects again persisted in recruiting all muscles rather than eliminating the noisy one. Such habitual coordination patterns were also unaffected by real modifications of biomechanics produced by selectively damaging a muscle without affecting sensory feedback. Subjects naturally use different patterns of muscle contraction to produce the same forces in different pronation-supination postures, but when the simulation was based on a posture different from the actual posture, the recruitment patterns tended to agree with the actual rather than the simulated posture. The results appear inconsistent with computation of motor programs by an optimal controller in the brain. Rather, the brain may learn and recall command programs that result in muscle coordination patterns generated by lower sensorimotor circuitry that are functionally "good-enough."