Stability in a frontal plane model of balance requires coupled changes to postural configuration and neural feedback control
Stability in a frontal plane model of balance requires coupled changes to postural configuration and neural feedback control
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DOI：
10.1152/jn.00010.2011
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发表时间：
2011-07-01
影响因子：
2.5
通讯作者：
Ting, Lena H.
中科院分区：
文献类型：
--
作者：
Bingham, Jeffrey T.;Choi, Julia T.;Ting, Lena H.
Bingham JT，Choi JT，Ting LH.额面平衡模型的稳定性需要姿势配置和神经反馈控制的耦合变化。J Neurophysiol 106：437-448，2011.首次发表于2011年5月4日; doi：10.1152/jn.00010.2011。姿势稳定性取决于肌肉骨骼系统和神经控制机制之间的相互作用。我们提出了一个额状面模型稳定的延迟反馈来分析的影响，改变立场的宽度对姿势的扰动反应。我们假设改变站立宽度会改变身体的机械动力学，并限制产生稳定姿势行为的延迟反馈增益的范围。令人惊讶的是，机械稳定性被发现降低作为立场宽度增加，由于有效惯性降低。此外，由于感觉运动延迟和增加杠杆髋关节扭矩的质心运动，稳定延迟反馈增益的幅度随着站立宽度的增加而减小。此外，稳定的反馈增益的范围是不重叠的跨越不同的立场宽度，使使用一个单一的神经反馈控制策略，在狭窄和广泛的立场可能会导致不稳定。稳定反馈增益集进一步减少了脚抬离和扰动幅度的约束。模拟适合实验测量的运动学，并确定的反馈增益证实了模型预测。此外，线性化系统的分析增益裕度被发现预测阶跃过渡，而不需要仿真。总之，该模型提供了一种方法来分离姿势配置，延迟的感觉运动反馈，和非线性的脚抬离约束之间的复杂的相互作用。该模型表明，只有当延迟神经反馈增益减小时，才能实现宽姿态下的稳定性。这个模型可能是有用的，在解释预期和矛盾的变化，在健康和神经功能受损的个人的立场宽度。
Bingham JT, Choi JT, Ting LH. Stability in a frontal plane model of balance requires coupled changes to postural configuration and neural feedback control. J Neurophysiol 106: 437-448, 2011. First published May 4, 2011; doi:10.1152/jn.00010.2011.-Postural stability depends on interactions between the musculoskeletal system and neural control mechanisms. We present a frontal plane model stabilized by delayed feedback to analyze the effects of altered stance width on postural responses to perturbations. We hypothesized that changing stance width alters the mechanical dynamics of the body and limits the range of delayed feedback gains that produce stable postural behaviors. Surprisingly, mechanical stability was found to decrease as stance width increased due to decreased effective inertia. Furthermore, due to sensorimotor delays and increased leverage of hip joint torque on center-of-mass motion, the magnitudes of the stabilizing delayed feedback gains decreased as stance width increased. Moreover, the ranges of the stable feedback gains were nonoverlapping across different stance widths such that using a single neural feedback control strategy at both narrow and wide stances could lead to instability. The set of stable feedback gains was further reduced by constraints on foot lift-off and perturbation magnitude. Simulations were fit to experimentally measured kinematics, and the identified feedback gains corroborated model predictions. In addition, analytical gain margin of the linearized system was found to predict step transitions without the need for simulation. In conclusion, this model offers a method to dissociate the complex interactions between postural configuration, delayed sensorimotor feedback, and nonlinear foot lift-off constraints. The model demonstrates that stability at wide stances can only be achieved if delayed neural feedback gains decrease. This model may be useful in explaining both expected and paradoxical changes in stance width in healthy and neurologically impaired individuals.