Flexible Recruitment of Balance Mechanisms to Environmental Constraints During Walking
Flexible Recruitment of Balance Mechanisms to Environmental Constraints During Walking
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DOI：
10.3389/frvir.2020.00005
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发表时间：
2020-08-07
影响因子：
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通讯作者：
Jeka, John
中科院分区：
文献类型：
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作者：
Fettrow, Tyler;DiBianca, Stephen;Jeka, John
背景：人类在行走时需要主动控制直立姿势，以避免失去平衡。对于人类在行走过程中如何调节平衡，特别是在复杂的环境中，我们还没有一个全面的理论。神经系统必须处理环境的许多方面，以产生适当的运动输出，以保持两条腿的平衡。我们之前已经确定了年轻健康成年人在行走时用来保持平衡的三种平衡机制：（1）踝关节滚动机制，踝关节内翻/外翻的调节； (2) 置脚机构，摆动式移脚置位； (3)推出机制，双站立时踝关节跖屈角度的调节。我们知道这些机制是相互依赖的，并且可能受到步态周期阶段和行走节奏等内部因素的影响。在这里，我们试图确定在存在环境限制的情况下行走时平衡的神经控制是否发生变化。方法：受试者在自定进度的跑步机上行走，同时沉浸在提供三种不同颜色路径的虚拟环境中。受试者被指示不要踏入禁行区，该区域出现在受试者的右侧或左侧。行走时，受试者会以电流前庭刺激的形式受到平衡扰动，从而产生侧身跌倒的感觉，要么朝向无步区，要么朝向另一侧的中性区。 结果：结果表明，平衡机制的使用会根据感知到的跌倒是朝向无步区还是中性区而改变。与中性刺激相比，参与者增加了对无步刺激的外侧踝关节和足部放置机制的使用，导致质心 (CoM) 发生更大的移动。结论：该实验进一步证明步行过程中的平衡控制系统极其灵活，在步态周期的不同时间招募多种机制来适应环境限制。
Background: Humans need to actively control their upright posture during walking to avoid loss of balance. We do not have a comprehensive theory for how humans regulate balance during walking, especially in complex environments. The nervous system must process many aspects of the environment to produce an appropriate motor output in order to maintain balance on two legs. We have previously identified three balance mechanisms that young healthy adults use to maintain balance while walking: (1) The ankle roll mechanism, a modulation of ankle inversion/eversion; (2) The foot placement mechanism, a shift of the swing foot placement; and (3) The push-off mechanism, a modulation of the ankle plantarflexion angle during double stance. We know that these mechanisms are interdependent and can be influenced by internal factors such as the phase of the gait cycle and walking cadence. Here we seek to determine whether there are changes in neural control of balance when walking in the presence of environmental constraints.Methods: Subjects walked on a self-paced treadmill while immersed in a virtual environment that provides three different colored pathways. Subjects were instructed not to step in the No-Step Zone, which appeared either on the right or left side of the subject. While walking, subjects received balance perturbations in the form of galvanic vestibular stimulation, providing the sensation of falling sideways, either toward the No-Step zone or toward the Neutral zone on the other side.Results: The results indicate that the use of the balance mechanisms are altered depending on whether the perceived fall is toward the No-Step or the Neutral zone. Participants increased the use of the lateral ankle and foot placement mechanisms for No-Step stimuli resulting in a larger shift of the center of mass (CoM) compared to the Neutral stimuli.Conclusion: This experiment provides further evidence that the balance control system during walking is extremely flexible, recruiting multiple mechanisms at different times in the gait cycle to adapt to environmental constraints.