Frequency-dependent force direction elucidates neural control of balance.
Frequency-dependent force direction elucidates neural control of balance.
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频率依赖力的方向阐明了神经控制的平衡。
DOI：
10.1186/s12984-021-00907-2
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发表时间：
2021-09-25
影响因子：
5.1
通讯作者：
Hogan N
中科院分区：
文献类型：
--
作者：
Shiozawa K;Lee J;Russo M;Sternad D;Hogan N
保持直立姿势是一项不稳定的任务，需要复杂的神经肌肉控制。人类使用脚-地面相互作用力，其特征在于应用点，幅度和方向来管理身体加速度。当在频域中分析站立的人的地面反作用力的方向时，先前的工作在不同的频带中发现了一致的模式。为了测试这种频率依赖性行为是否提供了神经控制的独特特征，或者是生物力学的必然结果，本研究模拟了安静站立，并将结果与人类受试者数据进行了比较。为了开发最简单的胜任和神经力学合理的动态模型，可以解释在多个受试者中观察到的模式，我们首先探索了模型所需的最小自由度。然后，我们应用了一种成熟的最优控制方法，该方法被参数化以最大化生理相关的洞察力来稳定平衡模型。如果一个站立的人被建模为一个单倒立摆，没有控制器可以重现实验观察到的模式。最简单的主管模型，近似一个站立的人是一个双倒立摆与扭矩驱动的踝关节和髋关节。一系列的控制器参数可以稳定这个模型，并重现实验数据中观察到的一般趋势，这一结果似乎表明生物力学的约束，而不是控制的后果。然而，频率依赖性模式的细节在测试的控制参数值之间变化很大。最能再现人类实验结果的一组参数表明，人类受试者为保持安静站立而采用的控制策略最好用最小的控制努力来描述，重点是脚踝扭矩。研究结果表明，在安静的站立观察到的地面反作用力的频率依赖性模式传达了人类控制策略的定量信息。这项研究的方法可能会扩展到调查人类神经控制策略在不同的背景下的平衡，如辅助设备或在神经受损的科目。
Maintaining upright posture is an unstable task that requires sophisticated neuro-muscular control. Humans use foot–ground interaction forces, characterized by point of application, magnitude, and direction to manage body accelerations. When analyzing the directions of the ground reaction forces of standing humans in the frequency domain, previous work found a consistent pattern in different frequency bands. To test whether this frequency-dependent behavior provided a distinctive signature of neural control or was a necessary consequence of biomechanics, this study simulated quiet standing and compared the results with human subject data. Aiming to develop the simplest competent and neuromechanically justifiable dynamic model that could account for the pattern observed across multiple subjects, we first explored the minimum number of degrees of freedom required for the model. Then, we applied a well-established optimal control method that was parameterized to maximize physiologically-relevant insight to stabilize the balancing model. If a standing human was modeled as a single inverted pendulum, no controller could reproduce the experimentally observed pattern. The simplest competent model that approximated a standing human was a double inverted pendulum with torque-actuated ankle and hip joints. A range of controller parameters could stabilize this model and reproduce the general trend observed in experimental data; this result seems to indicate a biomechanical constraint and not a consequence of control. However, details of the frequency-dependent pattern varied substantially across tested control parameter values. The set of parameters that best reproduced the human experimental results suggests that the control strategy employed by human subjects to maintain quiet standing was best described by minimal control effort with an emphasis on ankle torque. The findings suggest that the frequency-dependent pattern of ground reaction forces observed in quiet standing conveys quantitative information about human control strategies. This study’s method might be extended to investigate human neural control strategies in different contexts of balance, such as with an assistive device or in neurologically impaired subjects.
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影响因子：
2.4
作者：
Runge, CF;Shupert, CL;Zajac, FE
通讯作者：
Zajac, FE
影响因子：
2
作者：
Duarte, Marcos;Sternad, Dagmar
通讯作者：
Sternad, Dagmar
影响因子：
4.6
作者：
Park, Yoonjin;Lee, Kyunghwa;Lee, SeungGwan
通讯作者：
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影响因子：
6.7
作者：
Horak, Fay B.
通讯作者：
Horak, Fay B.
DOI：
10.1098/rspa.2017.0404
发表时间：
2017-11-01
影响因子：
3.5
作者：
Mueller, Roy;Rode, Christian;Blickhan, Reinhard
通讯作者：
Blickhan, Reinhard