A feedback model reproduces muscle activity during human postural responses to support-surface translations
A feedback model reproduces muscle activity during human postural responses to support-surface translations
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DOI：
10.1152/jn.01110.2007
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发表时间：
2008-02-01
影响因子：
2.5
通讯作者：
Ting, Lena H.
中科院分区：
文献类型：
--
作者：
Welch, Torrence D. J.;Ting, Lena H.
虽然反馈模型已被用于模拟人体姿势控制中的身体运动，但尚不清楚在姿势响应期间由神经系统产生的肌肉激活模式是否也可以通过反馈控制过程来解释。我们调查了一个简单的反馈法是否可以解释肌肉激活的时间模式，在人类受试者的支持表面的翻译。在此之前，我们使用了一个单连杆倒立摆模型与延迟反馈控制器再现猫的姿势反应过程中的肌肉活动的时间模式。我们将该模型缩放到人体尺寸，并确定它是否可以在向前和向后的支撑表面扰动期间再现人体肌肉活动。通过优化，我们发现了三个反馈增益（钟摆加速度，速度和位移）和一个共同的时间延迟，使模型能够最好地匹配测量的肌电图（EMG）信号。对于每个肌肉和每个主题，在姿势反应过程中的EMG信号的整个时间过程在整个下半身的肌肉中被很好地重建，并且类似于从最优控制模型导出的解决方案。在踝部肌肉中，>75%的EMG变异性由模型重建引起。令人惊讶的是，超过67%的EMG变异性也在膝盖，臀部和骨盆肌肉中，即使这些关节的运动很小。虽然我们的优化没有明确要求，但摆运动学与主体质心（CoM）运动学很好地匹配。总之，这些结果表明，一组共同的反馈信号相关的任务级控制的CoM运动是用于在姿势控制过程中的肌肉活动的时间形成。
Although feedback models have been used to simulate body motions in human postural control, it is not known whether muscle activation patterns generated by the nervous system during postural responses can also be explained by a feedback control process. We investigated whether a simple feedback law could explain temporal patterns of muscle activation in response to support-surface translations in human subjects. Previously, we used a single-link inverted-pendulum model with a delayed feedback controller to reproduce temporal patterns of muscle activity during postural responses in cats. We scaled this model to human dimensions and determined whether it could reproduce human muscle activity during forward and backward support-surface perturbations. Through optimization, we found three feedback gains (on pendulum acceleration, velocity, and displacement) and a common time delay that allowed the model to best match measured electromyographic (EMG) signals. For each muscle and each subject, the entire time courses of EMG signals during postural responses were well reconstructed in muscles throughout the lower body and resembled the solution derived from an optimal control model. In ankle muscles, >75% of the EMG variability was accounted for by model reconstructions. Surprisingly, >67% of the EMG variability was also accounted for in knee, hip, and pelvis muscles, even though motion at these joints was minimal. Although not explicitly required by our optimization, pendulum kinematics were well matched to subject center-of-mass (CoM) kinematics. Together, these results suggest that a common set of feedback signals related to task-level control of CoM motion is used in the temporal formation of muscle activity during postural control.