Dealing with uncertain visual feedback while walking

视觉通过允许我们检测和定义环境的特性，接收和处理自我和物体运动的提示，以及确定四肢和身体相对于周围环境的位置，对行走做出了重要贡献。这些视觉过程既依赖于完整的视觉系统，也依赖于适当的凝视行为，有助于识别危险、通过障碍和控制脚部位置。神经系统必须将它从视觉接收的输入与其他感官来源相结合，以确定身体/四肢的状态，以控制和适应不同情况下的行走。然而，它面临着一个根本性的问题：如何应对不确定性。这种不确定性在一定程度上是由感官感受器的局限性造成的，比如眼睛，以及身体随着年龄或疾病的变化。此外，我们的环境随着我们在其中的互动和移动而不断变化。这导致了环境的不确定性，这可能源于不可预测的地形或行人和其他移动物体的轨迹，或者由环境照明的变化引起。这项研究计划的长期目标是确定神经系统如何解决视觉和环境的不确定性，以控制和适应行走。 这项拟议的研究将集中在三个相辅相成的目标上：(1)确定大脑在面对不确定性时如何适应改变的视觉输入；(2)确定不确定性对凝视分配的影响，以及在视觉引导下行走时人的视线位置和脚部位置之间的时空关系；以及(3)确定在复杂环境中行走时，随着视觉反馈不确定性的增加，神经系统如何重新加权前庭输入。在这些目标的实验中，个人将被要求在需要精确放置脚部和/或穿越不平坦/不规则地形的情况下行走。我们将量化脚部放置的准确性、平衡性，以及当个人适应环境的限制和由特殊眼镜、不可预测的物体运动或照明变化造成的视觉不确定性时，人们注视的位置。 这项拟议的研究计划将为神经系统如何处理行走时的不确定性提供基本的见解。鉴于视觉质量的类似变化在几种情况下都会发生，包括年龄、新处方镜片和眼病，详细了解大脑如何适应改变的视觉输入(目标1)是至关重要的。目标2将有助于我们理解凝视在自然环境中是如何分配的，凝视模式是如何学习的，以及这种对世界的视觉采样是如何与行走时的脚部放置相结合的。由于有效的凝视行为对使用人机界面(如交互显示器、军事模拟器)至关重要，识别指导凝视的因素以及凝视模式是如何学习的有助于它们的设计和使用中的培训。对目标3的研究将促进我们对运动控制感觉系统之间复杂相互作用的了解。总而言之，这些知识最终将导致创新战略，以改善神经和/或眼疾患者的移动性，并促进用于临床、军事和娱乐目的的脑/人机界面的设计。

Vision contributes essentially to walking by allowing us to detect and define properties of the environment, receive and process self- and object-motion cues, and determine the position of the limbs and body relative to our surroundings. These visual processes, which depend on both an intact visual system and appropriate gaze behaviour, facilitate the identification of hazards, negotiation of obstacles, and control of foot placement. The nervous system must integrate the input it receives from vision with other sensory sources to determine the state of the body/limbs to control and adapt walking in different situations. However, it is faced with a fundamental problem: how to deal with uncertainty. This uncertainty is created, in part, by the limitations of sensory receptors, such as the eye, and body changes from age or disease. In addition, our environment continually changes as we interact and move within it. This leads to environmental uncertainty, which may stem from unpredictable terrain or trajectories of pedestrians and other moving objects, or be caused by changes in ambient lighting. The long-term goal of this program of research is to determine how the nervous system resolves visual and environmental uncertainty to control and to adapt walking. The proposed research will focus on three complementary objectives: (1) Determine how the brain adapts to altered visual input in the face of uncertainty; (2) Determine the effects of uncertainty on the allocation of gaze and the spatiotemporal relationship between where a person looks and foot placement during visually guided walking; and (3) Identify how the nervous system re-weights vestibular input with increased visual feedback uncertainty while walking in complex environments. In the experiments of these objectives, individuals will be required to walk in situations that require precise foot placement and/or across uneven/irregular terrain. We will quantify foot placement accuracy, balance, and where people fixate as individuals adapt to the constraints of the environment and visual uncertainty created by special glasses, unpredictable motion of objects, or changes in lighting. The proposed program of research will provide fundamental insight into how the nervous system deals with uncertainty while walking. A detailed understanding of how the brain adapts to altered visual input (Objective 1) is essential given that analogous changes in the quality of vision occur in several situations, including with age, new prescription lenses, and eye disease. Objective 2 will facilitate our understanding about how gaze is allocated in natural environments, how gaze patterns are learned, and how this visual sampling of the world is coupled to foot placement while walking. Because efficient gaze behaviour is essential for using human-machine interfaces (e.g., interactive displays, military simulators), identification of the factors that guide gaze and how gaze patterns are learned can assist in their design and training in their use. Research of Objective 3 will advance our knowledge of the complex interaction between sensory systems for the control of movement. Together, this knowledge will ultimately lead to innovative strategies to improve the mobility of those with neurological and/or eye disease, and facilitate the design of brain/human-machine interfaces used for clinical, military, and entertainment purposes.