Stepping to recover balance in complex environments: Is online visual control of the foot motion necessary or sufficient?
Stepping to recover balance in complex environments: Is online visual control of the foot motion necessary or sufficient?
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DOI：
10.1016/j.neulet.2008.08.062
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发表时间：
2008-11-07
影响因子：
2.5
通讯作者：
Maki, Brian E.
中科院分区：
文献类型：
--
作者：
Scovil, Carol Y.;Zettel, John L.;Maki, Brian E.
由平衡扰动引起的快速步进反应必须适应障碍物和其他环境特征对肢体运动的约束。最近的研究结果表明，所需的视觉空间信息（VSI）的收购和存储“主动”，扰动发作（PO）之前，然而，在何种程度上“在线”（PO后）视觉反馈可以作出贡献是未知的。为了研究这一点，我们使用了大的不可预测的平台扰动来引起快速的阶跃反应，而受试者佩戴遮挡视力的液晶护目镜：（1）PO之前（强制使用在线VSI），（2）PO之后（强制使用存储的VSI），或（3）根本不佩戴（正常VSI）。受试者站在一个障碍物后面，在这个障碍物中，一个狭窄的狭槽的位置在两次试验之间不可预测地变化，在向前一步反应期间，脚必须通过这个狭槽移动。在能够完成这项任务的受试者中（8名受试年轻人中有6名），储存VSI和正常VSI试验的反应非常相似。然而，在在线VSI试验中，通过槽的脚步离开时间延迟（平均约50 ins）。据推测，这种延迟允许更多的时间来获取和处理关于所需足部轨迹的在线VSI，但在在线VSI试验中，受试者仍然更有可能选择"错误"的足部（狭槽位置的对侧），并在将足部移动通过狭槽时接触屏障。这些结果表明，存储VSI在步骤的最早阶段，在选择步骤肢体和规划初始轨迹的关键作用。所需VSI的在线获取和处理可能太慢而不能有效地控制该早期阶段，特别是在对精确的足部运动的要求很高的情况下。(C)2008爱思唯尔爱尔兰有限公司保留所有权利。
Rapid step reactions evoked by balance perturbation must accommodate constraints on limb motion imposed by obstacles and other environmental features. Recent results suggest that the required visuospatial information (VSI) is acquired and stored "proactively", prior to perturbation onset (PO); however, the extent to which "online" (post-PO) visual feedback can contribute is not known. To study this, we used large unpredictable platform perturbations to evoke rapid step reactions, while subjects WORE liquid crystal goggles that occluded vision: (I) prior to PO (forcing use of online-VSI), (2) after PO (forcing use of stored-VSI), or (3) not at all (normal-VSI). Subjects stood behind a barrier in which the location of a narrow slot, through which the foot had to be moved during forward step reactions, was varied unpredictably, between trials. Within subjects who were able to do the task (6 of 8 young adults tested), responses in stored-VSI and normal-VSI trials were very similar. However, in online-VSI trials, the foot-off time for the step through the slot was delayed (by similar to 50 ins, on average). Presumably, this delay allowed more time to acquire and process online-VSI regarding the required foot trajectory, yet subjects were still more likely to select the "wrong" foot (contralateral to the slot location) and to contact the barrier while moving the foot through the slot, in online-VSI trials. These results suggest a critical role for stored-VSI during the earliest phase of the step, in selecting the step limb and planning the initial trajectory. online acquisition and processing of the required VSI may be too slow to allow effective control of this early phase, particularly in situations where the demands for accurate foot motion are high. (C) 2008 Elsevier Ireland Ltd. All rights reserved.