Minimizing Instability with Dynamic Visual Inputs

描述（由申请人提供）：该项目的长期目标是了解如何通过使用动态视觉环境来促进运动和姿态控制过程中的感觉运动再学习来帮助平衡和步态障碍。当前庭输入变得不可靠时，无论是由于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产生适当的反应，以改变姿势方向或平衡。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没有被证明是一种完全成功的干预，可能是因为控制的输入没有对姿势系统的功能提出必要的要求。个体可能会固定在一种反应模式上，而无法适应环境中遇到的各种干扰。我们拟研究正常受试者和双侧迷路丢失患者在动态视觉环境下运动时的姿势反应和空间定向的变化。我们假设患有前庭功能丧失的个体固定在一种补偿策略上，无法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个体补偿不稳定。受试者将在安静的姿势和在跑步机上行走时接受测试，而我们将操纵动态虚拟环境的速度或上下文对比。通过重复测量方差分析（anova）来测量和分析节段偏移和压力中心，以确定姿态组织和方向是否受到外围视野特定参数的影响。最不稳定的参数将被应用于一个训练项目中，在这个项目中，受试者将被指示关注远处的目标或内部反馈，以确定在动态视觉环境中的主动表现是否会增加迷路丧失患者的反应能力。最后，我们将评估在动态视觉环境中是否存在训练的功能延续。受试者将执行一个模拟物理世界的任务，在这个任务中，他们必须在他们周围的世界移动和他们的道路上出现障碍的时候，取回并放置一个物体。这些研究的结果将为视觉-前庭相互作用的动力学提供深入的见解，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.