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首页> 外文期刊>Experimental Brain Research >Can stabilizing features of rapid triggered stepping reactions be modulated to meet environmental constraints?
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Can stabilizing features of rapid triggered stepping reactions be modulated to meet environmental constraints?

机译：可以对快速触发的步进反应的稳定特征进行调节以满足环境限制吗？

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摘要

This study examined whether the stabilizing features of rapid triggered compensatory stepping reactions can be modulated to accommodate an environmental constraint, in the form of an obstacle placed in front of the subject. The compensatory stepping reactions were evoked, in 11 healthy young adults, by unpredictable multidirectional platform translation; the forward-step reactions evoked by large backward translations were analyzed. Clearance of the obstacle required a doubling of the usual (no obstacle) swing duration and therein presented significant challenges to both anteroposterior (a-p) and lateral stability, yet the central nervous system (CNS) was able to decelerate and stabilize the body’s center of mass (COM) without taking additional steps. Findings that the response was modulated successfully without prior practice or exposure to the perturbation suggest that the CNS automatically incorporates exteroceptive information into the control of compensatory stepping. Control of a-p stability appeared primarily to involve an increase in forward step distance. Surprisingly, the control of lateral stability involved both an anticipatory postural adjustment (APA) and lateral step placement. By including a much larger APA prior to foot-lift (137% increase in amplitude and 50% increase in duration versus no-obstacle trials), the COM was propelled to a more stable position prior to swing phase. This was achieved with minimal (32 ms) delay in foot-lift, due, in part, to more rapid initiation and execution of limb unloading. In contrast to previous findings that APAs are commonly absent or severely reduced during compensatory stepping, the present results demonstrate that large APAs can be incorporated into these reactions when demanded by task conditions. However, these large APAs were still insufficient to counter the increased tendency of the COM to fall during the prolonged swing phase. The fact that the APA was included at all may indicate a hybrid control, in which predictive control (via APA) is used to reduce the anticipated lateral instability, and reactive control of the final foot placement, governed by sensory discharge related to the actual COM motion, provides any additional stabilization required.
机译：这项研究检查了是否可以对快速触发的补偿性步进反应的稳定特征进行调节以适应环境限制，以障碍物的形式放置在受试者的前方。通过不可预测的多向平台转换，在11名健康的年轻人中引起了补偿性的步进反应；分析了由大型反向翻译引起的前向反应。清除障碍物需要将通常的（无障碍物）挥杆持续时间增加一倍，从而对前后（ap）和侧向稳定性都提出了重大挑战，而中枢神经系统（CNS）却能够使身体的质心减速和稳定（COM），而无需采取其他步骤。发现在没有事先实践或没有扰动的情况下成功地调制了响应，这表明CNS会自动将兴奋性信息纳入补偿性步进控制中。控制a-p稳定性似乎主要涉及向前步距的增加。出人意料的是，对侧向稳定性的控制涉及预期的姿势调整（APA）和侧向台阶放置。通过在抬脚之前增加一个更大的APA（与无障碍试验相比，幅度增加了137％，持续时间增加了50％），COM在摆动阶段之前被推到了更稳定的位置。之所以能够做到这一点，是因为最小程度地（32毫秒）的抬举延迟，部分原因是肢体卸载的启动和执行更加迅速。与以前的发现相反，在补偿性步进过程中APA通常不存在或严重降低，本研究结果表明，当任务条件需要时，可以将大量APA纳入这些反应。但是，这些大的APA仍然不足以抵消COM在长时间摆动阶段下降的趋势。完全包含APA的事实可能表明存在混合控制，其中预测控制（通过APA）用于减少预期的侧向不稳定性，并通过与实际COM相关的感觉放电来控制最终足部的反应性控制。运动，提供所需的任何其他稳定作用。

著录项

  • 来源
    《Experimental Brain Research》 |2002年第3期|297-308|共12页
  • 作者

    John L. Zettel; William E. McIlroy; Brian E. Maki;

  • 作者单位

    Centre for Studies in Aging Sunnybrook and Women’s College Health Sciences Centre University of TorontoInstitute of Medical Science University of TorontoInstitute of Biomaterials and Biomedical Engineering University of Toronto;

    Centre for Studies in Aging Sunnybrook and Women’s College Health Sciences Centre University of TorontoGraduate Department of Rehabilitation Science University of Toronto;

    Centre for Studies in Aging Sunnybrook and Women’s College Health Sciences Centre University of TorontoInstitute of Medical Science University of TorontoDepartment of Surgery University of Toronto;

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  • 正文语种 eng
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  • 关键词

    Anticipatory postural adjustments; Obstacle clearance; Postural balance; Stepping; Triggered reactions;

    机译：预期姿势调整;障碍物清除;姿势平衡;踩踏;触发反应;

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