Department of Physical Therapy and Human Movement Sciences, Northwestern University, 645 N Michigan Ave, Suite 1100, Chicago, IL, 60611, USA.
Research Service, Edward Hines Jr. VA Hospital, 5000 5th Ave, Hines, IL, 60141, USA.
Exp Brain Res. 2023 Oct;241(10):2535-2546. doi: 10.1007/s00221-023-06704-8. Epub 2023 Sep 13.
People use vision to inform motor control strategies during walking. With practice performing a target stepping task, people shift their gaze farther ahead, transitioning from watching their feet contact the target to looking for future target locations. The shift in gaze focus suggests the role of vision in motor control changes from emphasizing feedback to feedforward control. The present study examines whether changing visual fixation location is accompanied by a similar change in reliance upon visual information. Twenty healthy young adults practiced stepping on moving targets projected on the surface of a treadmill. Periodically, participants' visual reliance was probed by hiding stepping targets which inform feedback or feedforward (targets < or > 1.5 steps ahead, respectively) motor control strategies. We calculated visual reliance as the increase in step error when targets were hidden. We hypothesized that with practice, participant reliance on feedback visual information would decrease and their reliance on feedforward visual information would increase. Contrary to our hypothesis, participants became significantly more reliant on feedback visual information with practice (p < 0.001) but their reliance on feedforward visual information did not change (p = 0.49). Participants' reliance on visual information increased despite looking significantly farther ahead with practice (p < 0.016). Together, these results suggest that participants fixated on feedback information less. However, changes in fixation pattern did not reduce their reliance upon feedback information as stepping performance still significantly decreased when feedback information was removed after training. These findings provide important context for how the role of vision in controlling walking changes with practice.
人们在行走时利用视觉来调整运动控制策略。通过反复练习目标跨步任务,人们会将目光移得更远,从注视脚部接触目标过渡到寻找未来的目标位置。目光焦点的转移表明,视觉在运动控制中的作用从强调反馈转变为强调前馈控制。本研究考察了改变视觉固定位置是否伴随着对视觉信息依赖的类似变化。二十名健康的年轻成年人在跑步机表面上练习向移动目标跨步。定期隐藏告知反馈或前馈(分别为目标<或>1.5 步)运动控制策略的跨步目标,以探测参与者的视觉依赖程度。我们将视觉依赖程度定义为隐藏目标时步幅误差的增加。我们假设,随着练习,参与者对反馈视觉信息的依赖会减少,而对前馈视觉信息的依赖会增加。与我们的假设相反,参与者在练习中对反馈视觉信息的依赖显著增加(p<0.001),但对前馈视觉信息的依赖没有变化(p=0.49)。尽管参与者在练习中明显将目光投向更远的前方(p<0.016),但他们对视觉信息的依赖却增加了。这些结果表明,参与者注视反馈信息的次数减少了。然而,固定模式的变化并没有减少他们对反馈信息的依赖,因为在训练后移除反馈信息时,跨步性能仍然显著下降。这些发现为视觉在控制行走中的作用如何随练习而改变提供了重要的背景信息。