Identifying potential cortical mechanisms responsible for gait impairment in older adult fallers

项目摘要 关于老年人步态障碍和跌倒风险的皮质机制的知识不足， 制定有效的跌倒预防干预措施。为了改善目前的步态评估和 在老年人的干预措施中，需要对步态表现进行更完整的量化。电流 步态期间皮质活动的量化主要限于前额皮质（PFC）和年轻人。 缺乏有关后顶叶皮层（PPC;视觉处理的方向和运动的 在步态期间的空间中的身体）活动进一步限制了当前跌倒文献的可解释性。老年 与年轻人相比，成年人的视觉处理速度较慢，因此，建立PPC在步态中的作用， 老年人跌倒者和非跌倒者对于理解PPC在跌倒风险中的作用至关重要。拟议 这项研究的重要贡献包括在老年人完成视觉复杂步态任务时定义皮层活动。 并确定皮质活动如何影响老年人步态和跌倒预测因子之间的关系 fallers和non-fallers。这一贡献是重要的，因为它将确定PPC的未知作用， 老年跌倒者和非跌倒者视觉复杂步态表现期间的PFC，这将指导更多 有效的预防措施。这项拟议的研究是创新的，因为它量化了PPC活动 在需要持续视觉处理的视觉复杂步态任务期间，模仿 家庭和社区环境。这项建议的主要目的是比较大脑皮层的活动， 年轻人、健康老年人和老年人跌倒者的PPC和PFC以及关键步态指标， 复杂的步态任务，并阐明PPC和PFC活动对步态和跌倒之间的关系的影响 老年人跌倒者和非跌倒者的预测因子。这项建议涉及以下具体目标： 目的1：年龄和跌倒状态对步态期间PPC和PFC活动的影响 假设1：老年人的氧合血红蛋白浓度增加，脱氧血红蛋白浓度降低， 步态和步态变异性期间的PPC和PFC，并降低动态稳定性和步长调整精度 比年轻的成年人。老年跌倒者的皮层活动和步态变异性最大， 动态稳定性和步进调节精度。从离地到踏石跑步机步态的PPC活动 对于老年人来说，这将是最大的，因为他们将无法迅速处理增加的视觉刺激。 目的2：通过皮层活动调节步态表现和跌倒预测因子的关系 假设2：步态表现和福尔斯之间的关系已被研究，然而，皮质 活动介导这种关系是未知的。皮质活动，特别是PPC活动，将是一个重要的 调节步态性能（动态稳定性、可变性和步长调整）之间关系的媒介 准确性）和跌倒预测因素（跌倒史和害怕跌倒）。这将是第一个严格的 分析老年跌倒者和非跌倒者的步态表现、PPC和PFC活动以及跌倒预测因素。

Project Summary Insufficient knowledge about the cortical mechanisms of gait impairment and fall risk in older adults limits the development of effective fall prevention interventions. In order to improve the current gait assessments and interventions in older adults, a more complete quantification of gait performance is required. Current quantification of cortical activity during gait is mostly limited to the prefrontal cortex (PFC) and young adults. The lack of information about the posterior parietal cortex (PPC; visual processing of orientation and motion of the body in space) activity during gait further limits the interpretability of the current fall literature. Older adults' visual processing is slower compared to young adults, therefore, establishing the PPC's role in gait for older adult fallers and non-fallers is critical for understanding the role of the PPC in fall risk. The proposed study's significant contributions include defining cortical activity during a visually complex gait task in older adults and establish how cortical activity affects the relationship between gait and fall predictors in older adult fallers and non-fallers. This contribution is significant because it will identify the unknown roles of the PPC and PFC during visually complex gait performance in older adult fallers and non-fallers, which will guide more effective fall prevention interventions. This proposed study is innovative because it quantifies PPC activity during a visually complex gait task that requires constant visual processing, mimicking gait demands in the home and community environments. The primary purpose of this proposal is to compare cortical activity in the PPC and PFC and key gait metrics in young, healthy older and older adult fallers during increasingly complex gait tasks and elucidate the effect PPC and PFC activity have on the relationship between gait and fall predictors in older adult fallers and non-fallers. This proposal addresses the following specific aims: Aim 1: Effects of age and fall status on PPC and PFC activity during gait Hypothesis 1: Older adults will have increased oxy- and decreased deoxygenated hemoglobin concentrations in the PPC and PFC during gait and gait variability, and reduced dynamic stability and step adjustment accuracy than young adults. Older adult fallers will exhibit the most cortical activity and gait variability, and least dynamic stability and step adjustment accuracy. PPC activity from over ground to stepping-stone treadmill gait will be greatest for the older adult fallers, as they will be unable to swiftly process the added visual stimuli. Aim 2: Mediation of the gait performance and fall predictor relationship by cortical activity Hypothesis 2: The relationship between gait performance and falls has been examined, however, how cortical activity mediates this relationship is unknown. Cortical activity, especially PPC activity, will be a significant mediator to the relationship between gait performance (dynamic stability, variability, and step adjustment accuracy) and fall predictors (fall history and fear of falling) in older adults. This will be the first rigorous analyses of gait performance, PPC and PFC activity, and fall predictors in older adult fallers and non-fallers.