Balance Control Mechanisms, Age-Related Changes, and Methods for Improvement of Balance During Gait

 描述（由申请人提供）： 目的：目的是了解在站立和行走步态中维持内外侧（ML）平衡的机制以及年龄如何影响这些机制。重点是ML平衡，因为之前的证据表明ML方向的稳定性比前后方向的问题更大，并且老年人中相当大比例的福尔斯摔倒发生在ML方向。根据初步结果，另一个目标是开始平衡辅助装置的原型开发，该平衡辅助装置可能改善步态期间的平衡，并降低影响平衡的缺陷受试者的福尔斯可能性。计划：该提案包括4个目标，其中三个研究步态期间平衡的神经控制的不同方面，一个目标建议应用其他目标的结果，以探索假体的开发，以提高步态期间的稳定性。在步态期间平衡的神经控制需要调节运动的两个不同方面。第一个方面涉及控制身体在空间中和相对于环境的定向的机制。这方面需要整合来自多个感觉系统（视觉，前庭，本体感受和体感）的信息，并随后产生适当的运动动作，以保持所需的身体姿势。目标1将描述步态过程中多感官对方向控制的影响，将其与站立的结果进行比较，并确定年龄如何影响这些方向控制机制。步态期间平衡控制的第二个方面涉及保持动态平衡的机制。动态平衡是指身体运动的振荡模式，发生在每个步骤周期。多 控制机制是动态平衡的潜在贡献者，包括基于调节步进定时的机制。这种步进定时机制目前还没有被认为是动态平衡的主要贡献者，但我们的初步结果揭示了它的重要性。目的2实验将描述有助于动态平衡的机制，并确定年龄对这些机制的影响。目标3将主要确定使用我们提出的方法获得的步态测量是否对应于通过传统方法获得的步态测量。目标4将探索开发一种平衡辅助器，通过基于身体运动的测量触发步进来改善步态期间的平衡。研究方法：参与者将主要从NCRAR现有的志愿者数据库中招募，这些志愿者表示愿意参加NCRAR的研究项目。这个数据库中至少有50%的受试者是退伍军人。受试者组将包括年轻退伍军人（年龄18至45岁）和老年退伍军人（>65岁），每组20名受试者。受试者将填写筛选问卷，该问卷提供平衡信心的自我评级，并已显示与预测福尔斯可能性的临床检查相关。目标1和2实验将在定制平衡测试设备上进行，该设备可以通过倾斜平台表面或受试者观察到的视觉场景来提供受控干扰。参与者要么站在平台表面上，要么在ML平衡控制方面执行具有与正常行走步态相似特征的原地踏步步态。记录的数据包括身体摇摆测量，平台力，步宽，步的时间，以及实际的表面和视觉场景运动。目标3和4将使用前庭电刺激来扰乱行走期间的平衡。数据分析将量化身体摇摆的措施，确定刺激-反应关系，并确定不同的动态平衡控制机制的贡献。将结合站立和步态期间的现有平衡数学模型，以解释实验数据，从而使识别的模型参数具有生理学意义，并提供跨年龄组比较的结局指标。年轻人和老年人的结果之间的统计比较将确定年龄影响步态平衡的程度。

 DESCRIPTION (provided by applicant): Objectives: The objectives are to understand the mechanisms that maintain medial-lateral (ML) balance during stance and walking gait and how age affects these mechanisms. The focus is on ML balance because previous evidence indicates that stability is more problematic in the ML direction than in the anterior-posterior direction and that a sizable proportion of falls in older individuals occur in the ML direction. Based on preliminary results, an additional objective is to begin prototype development of a balance aid that could potentially improve balance during gait and reduce the likelihood of falls in subjects with deficits that affect balance. Plan: The proposa includes 4 Aims, three of which investigate different aspects of the neural control of balance during gait and one Aim that proposes to apply results from the other Aims to explore development of a prosthesis to improve stability during gait. The neural control of balance during gait requires the regulation of two different aspects of movement. The first aspect involves the mechanism that controls body orientation in space and relative to the environment. This aspect requires the integration of information from multiple sensory systems (visual, vestibular, proprioceptive, and somatosensory) and the subsequent generation of appropriate motor actions that maintain a desired body posture. Aim 1 will characterize the multi-sensory influences on orientation control during gait, will compare them to results from stance, and will determine how age influences these orientation control mechanisms. The second aspect of balance control during gait involves mechanisms that maintain dynamic balance. Dynamic balance refers to the oscillating pattern of body motion that occurs with each step cycle. Multiple control mechanisms are potential contributors to dynamic balance, including a mechanism based on the regulation of step timing. This step-timing mechanism is not currently recognized as a major contributor to dynamic balance, but our preliminary results reveal its importance. Aim 2 experiments will characterize the mechanisms contributing to dynamic balance and determine the influence of age on these mechanisms. Aim 3 will primarily determine whether gait measures obtained using our proposed methods correspond to gait measures obtained by conventional methods. Aim 4 will explore development of a balance aid to improve balance during gait by triggering stepping based on measures of body motion. Methods: Participants will be recruited primarily from an existing NCRAR database of volunteers who have expressed willingness to participate in research projects at NCRAR. At least 50% of the subjects in this database are Veterans. Subject groups will include young Veterans (ages 18 to 45 years) and older Veterans (>65 years) with 20 subjects in each group. Subjects will fill out screening questionnaires that provide a self- rating of balance confidence and have been shown to correlate with clinical examinations that predict the likelihood of falls. Aim 1 and 2 experiments will be performed on a custom balance test device that can deliver controlled disturbances by tilting the platform surface or the visual scene viewed by the subject. Participants either stand on the platform surface or perform a stepping-in-place gait that has similar characteristics, in terms of ML balance control, as a normal walking gait. Recorded data include body sway measures, platform forces, step width, timing of steps, and actual surface and visual scene motion. Aims 3 and 4 will use galvanic vestibular stimulation to perturb balance during walking. Data analysis will quantify body sway measures, identify stimulus-response relationships, and identify the contributions of different mechanisms for dynamic balance control. Existing mathematical models of balance during stance and during gait will be combined to account for experimental data such that identified model parameters are physiologically meaningful and also provide outcome measures for comparison across age groups. Statistical comparison between results from younger and older adults will determine the extent to which age influences balance during gait.