Graci Valentina, Elliott David B, Buckley John G
Vision and Mobility Laboratory, Bradford School of Optometry and Vision Science, University of Bradford, Bradford, United Kingdom.
Optom Vis Sci. 2010 Jan;87(1):21-7. doi: 10.1097/OPX.0b013e3181c1d547.
To determine the relative importance to adaptive locomotion of peripheral visual cues provided by different parts of the visual field.
Twelve subjects completed obstacle crossing trials while wearing goggles that provided four visual conditions: upper visual field occlusion, lower visual field occlusion (LO), circumferential peripheral visual field occlusion (CPO), and full vision. The obstacle was either positioned as a lone structure or within a doorframe.
Given that subjects completed the task safely without cues from the lower or peripheral visual field, this suggests that subjects used exteroceptive information provided in a feed-forward manner under these conditions. LO and CPO led to increased foot placement distance from the obstacle and to increased toe clearance over the obstacle with a reduced crossing-walking velocity. The increased variability of dependent measures under LO and CPO suggests that exproprioceptive information from the peripheral visual field is generally used to provide online control of lower limbs. The presence of the doorframe facilitated lead-foot placement under LO by providing exproprioceptive cues in the upper visual field. However, under CPO conditions, the doorframe led to a further reduction in crossing velocity and increase in trail-foot horizontal distance and lead-toe clearance, which may have been because of concerns about hitting the doorframe with the head and/or upper body.
Our findings suggest that exteroceptive cues are provided by the central visual field and are used in a feed-forward manner to plan the gait adaptations required to safely negotiate an obstacle, whereas exproprioceptive information is provided by the peripheral visual field and used online to "fine tune" adaptive gait. The loss of the upper and lower peripheral visual fields together had a greater effect on adaptive gait compared with the loss of the lower visual field alone, likely because of the absence of lamellar flow visual cues used to control egomotion.
确定视野不同部分提供的周边视觉线索对适应性运动的相对重要性。
12名受试者戴着提供四种视觉条件的护目镜完成跨越障碍物试验：上视野遮挡、下视野遮挡（LO）、周边视野圆周遮挡（CPO）和全视野。障碍物要么作为单独结构放置，要么放置在门框内。
鉴于受试者在没有来自下视野或周边视野线索的情况下安全完成任务，这表明受试者在这些条件下以前馈方式使用了提供的外感受信息。LO和CPO导致与障碍物的足部放置距离增加，并且跨越障碍物时的脚趾间隙增加，同时行走速度降低。在LO和CPO下相关测量的变异性增加表明，来自周边视野的本体感受信息通常用于提供对下肢的在线控制。门框的存在通过在上视野中提供本体感受线索促进了LO下的领先足部放置。然而，在CPO条件下，门框导致跨越速度进一步降低，拖后足部水平距离增加以及领先脚趾间隙增加，这可能是因为担心头部和/或上身撞到门框。
我们的研究结果表明，外感受线索由中央视野提供，并以前馈方式用于规划安全通过障碍物所需的步态适应，而本体感受信息由周边视野提供并在线用于“微调”适应性步态。与仅失去下视野相比，上下周边视野同时丧失对适应性步态的影响更大，这可能是因为缺乏用于控制自我运动的层流视觉线索。
