Minimizing Instability with Dynamic Visual Inputs

描述(申请人提供)：这个项目的长期目标是了解如何通过使用动态视觉环境来帮助平衡和步态障碍，以促进运动和站立姿势控制中的感觉运动重新学习。当前庭输入变得不可靠时，无论是迷路丢失还是功能障碍，个体必须学会依赖视觉和本体感觉通路来对姿势方向或平衡的变化产生适当的反应。通过在静态环境中练习姿势和有目的的活动来产生感觉再学习的尝试并未被证明是完全成功的干预，可能是因为受控输入没有对姿势系统的功能提出必要的要求。个体可能固定在一种反应模式上，无法与环境中遇到的干扰范围相匹配。我们建议研究正常受试者和双侧迷路丧失患者在动态视觉环境中运动时姿势反应和空间定向的变化。我们假设，前庭丧失的个体固定在一种补偿策略上，不能补偿动态环境中波动的需求。我们将研究提供使用视觉信息的策略是否有助于这些人补偿不稳定。受试者将在安静的站姿和在跑步机上行走时接受测试，同时我们操纵动态虚拟环境的速度或背景对比度。节段偏移和压力中心将通过重复测量ANOVA进行测量和分析，以确定姿势组织和方向是否受外围视野的特定参数影响。出现的最不稳定的参数将应用于训练计划，在该计划中，受试者将被指示专注于远处的目标或内部反馈，以确定在动态视觉环境中的积极表现是否会增加迷宫丧失个体的反应能力。最后，我们将评估动态视觉环境中的培训是否存在功能转移。受试者将执行一项模拟的物理世界任务，在这个任务中，当世界在他们周围移动，障碍物出现在他们的路径上时，他们必须取回并放置一个物体。这些研究的结果将提供对视觉前庭相互作用的动力学的洞察，并为平衡障碍的治疗干预确定具体的定量方案。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how balance and gait disorders can be helped by using dynamic visual environments to facilitate sensorimotor relearning during locomotion and stance postural control. When vestibular inputs become unreliable, either from labyrinthine loss or dysfunction, individuals must learn to rely upon visual and proprioceptive pathways to produce appropriate responses for changes in postural orientation or equilibrium. Attempts to produce sensory relearning through practicing postural and purposeful activities in static environments have not proved to be a fully successful intervention, possibly because the controlled inputs do not place the necessary demands on the functionality of the postural system. Individuals may become fixed on one pattern of response and be unable to match the range of disturbances encountered in the environment. We propose to study changes in postural responses and spatial orientation during locomotion within a dynamic visual environment in normal subjects and in patients with bilateral labyrinthine loss. We hypothesize that individuals with vestibular loss become fixed on one strategy of compensation and cannot compensate for the fluctuating demands of a dynamic environment. We will examine whether providing strategies for using visual information assists these individuals in compensating for destabilization. Subjects will be tested during quiet stance and walking on a treadmill while we manipulate the velocity or contextual contrast of a dynamic virtual environment. Segmental excursions and center of pressure will be measured and analyzed with repeated measures ANOVAs to determine if postural organization and orientation is influenced by specific parameters of the peripheral field of view. The parameters that emerge as most destabilizing will be applied in a training program where subjects will be instructed to focus on a distant target or on internal feedback to determine if active performance in a dynamic visual environment increases the response repertoire of individuals with labyrinthine loss. Finally, we will assess whether there is functional carryover from training within a dynamic visual environment. Subjects will perform a simulated physical world task in which they must retrieve and place an object while the world moves around them and obstacles appear in their path. Results from these studies will provide insight into the dynamics of the visualvestibular interaction and identify specific quantitative protocols for therapeutic interventions with balance disorders.