Cognitive Systems Lab, Institute of Physics, Chemnitz University of Technology, Reichenhainer Str. 70, 09126, Chemnitz, Germany.
Physics of Cognition Group, Institute of Physics, Chemnitz University of Technology, 09126, Chemnitz, Germany.
Exp Brain Res. 2023 Mar;241(3):765-780. doi: 10.1007/s00221-023-06560-6. Epub 2023 Feb 2.
Walking is a complex task. To prevent falls and injuries, gait needs to constantly adjust to the environment. This requires information from various sensory systems; in turn, moving through the environment continuously changes available sensory information. Visual information is available from a distance, and therefore most critical when negotiating difficult terrain. To effectively sample visual information, humans adjust their gaze to the terrain or-in laboratory settings-when facing motor perturbations. During activities of daily living, however, only a fraction of sensory and cognitive resources can be devoted to ensuring safe gait. How do humans deal with challenging walking conditions when they face high cognitive load? Young, healthy participants (N = 24) walked on a treadmill through a virtual, but naturalistic environment. Occasionally, their gait was experimentally perturbed, inducing slipping. We varied cognitive load by asking participants in some blocks to count backward in steps of seven; orthogonally, we varied whether visual cues indicated upcoming perturbations. We replicated earlier findings on how humans adjust their gaze and their gait rapidly and flexibly on various time scales: eye and head movements responded in a partially compensatory pattern and visual cues mostly affected eye movements. Interestingly, the cognitive task affected mainly head orientation. During the cognitive task, we found no clear signs of a less stable gait or of a cautious gait mode, but evidence that participants adapted their gait less to the perturbations than without secondary task. In sum, cognitive load affects head orientation and impairs the ability to adjust to gait perturbations.
行走是一项复杂的任务。为了防止跌倒和受伤，步态需要不断适应环境。这需要来自各种感觉系统的信息；反过来，通过环境移动会不断改变可用的感觉信息。视觉信息可以从远处获得，因此在穿越困难地形时最为关键。为了有效地采样视觉信息，人类会调整他们的注视方向以适应地形，或者在实验室环境中面对运动扰动时调整。然而，在日常生活活动中，只有一小部分感觉和认知资源可以用于确保安全的步态。当人们面临高认知负荷时，他们如何应对具有挑战性的行走条件？年轻、健康的参与者（N=24）在跑步机上穿过一个虚拟但自然的环境行走。偶尔，他们的步态会受到实验性干扰，导致滑倒。我们通过在一些区块中要求参与者以七步为单位向后倒数来改变认知负荷；正交地，我们改变视觉提示是否表示即将发生的扰动。我们复制了之前关于人类如何在各种时间尺度上快速、灵活地调整注视和步态的发现：眼睛和头部运动以部分补偿的模式做出反应，视觉提示主要影响眼睛运动。有趣的是，认知任务主要影响头部方向。在认知任务中，我们没有发现步态不太稳定或谨慎步态模式的明显迹象，但有证据表明参与者对扰动的适应程度不如没有次要任务时高。总之，认知负荷会影响头部方向，并损害对步态扰动的适应能力。
