Individual-specific engagement of cortical resources for standing balance control in aging and post stroke

项目摘要 我们的长期目标是识别平衡健康和受损的神经机制，以机械地引导- 基于预测、评估和干预的方法，用于解决衰老中常见的平衡和步态障碍 和神经性疾病。众所周知，在临床上，皮质资源参与平衡控制 是包括中风幸存者在内的老年人跌倒风险的一个指标，根据平衡的退化推断 和/或当并发认知任务将注意力从平衡控制转移时的步态表现。一位科学的 改善平衡障碍的预后工具、预防策略和干预措施的障碍是我们 缺乏对皮质资源如何以及何时参与平衡控制的理解，尤其是在 平衡任务难度。我们建议的一个创新是确定直接的、机械性的皮质测量方法 反应性平衡期间的活动。我们将结合MPI Ting在反应性神经力学方面的专业知识 平衡控制和MPI Borich在人类电生理学方面的专业知识，以确定大脑之间的关系 活动和运动功能，以改善中风的康复。我们的目标是识别大脑皮质活动信号 区分个体水平、任务水平和群体水平的大脑皮质资源参与平衡的差异 年轻人(目标1)、老年人(目标2)和因中风而单侧损害的老年人的对照 (目标3)。我们将测量脑电(EEG)、肌电(EMG)和生物力学信号 在反应性平衡恢复到支撑面平移期间。我们建议使用这两种方法在临床上可行 基于电极的分析方法，以及机械上重要的解剖学信息功能 使用高密度脑电结合结构和功能磁共振扫描进行分析。我们假设 平衡控制期间的皮质活动信号以个体、年龄和疾病特有的方式增加 随着平衡任务难度的增加。在组内，我们预测大脑皮质活动的个体变异性为 用平衡挑战来解释，即将平衡任务难度归一化到步幅阈值，这是平衡的一种衡量标准 功能。然而，在组之间，我们预测皮层活动特征及其与平衡挑战的关系 会有所不同。我们的目标是由我们的初步数据激励的，这些数据显示：1)N1和Beta能力超过 平衡任务困难的腿部感觉运动区取决于年轻人和老年人的平衡功能2) 感觉运动功能连通性与平衡任务难度之间的相反关系。 老年人；3)感觉运动与前额运动相关的平衡功能的不同方面 老年人的连接性；以及4)卒中幸存者的感觉运动功能连接性与 步行功能。如果成功，我们将确定平衡健康的神经生理指标，这将广泛 适用于整个生命周期，适用于神经和骨科平衡障碍，显著 推进科学框架，实现个性化、机械化的精准医疗战略 评估和干预，以改善生活质量那些健康状况不佳的人。

Project Summary Our long-term goal is to identify neural mechanisms of healthy and impaired balance to guide mechanistically- based predictors, assessments, and interventions for addressing balance and gait impairments common in aging and neurological disorders. It is well-known clinically that engagement of cortical resources in balance control is an indicator of fall risk in older adults including stroke survivors, as inferred by the degradation of balance and/or gait performance when a concurrent cognitive task shifts attention away from balance control. A scientific barrier to improving prognostic tools, preventive strategies, and interventions for balance impairments is that we lack an understanding of how and when cortical resources are engaged in balance control, particularly with balance task difficulty. An innovation of our proposal is to identify direct, mechanistic measures of cortical activity during reactive balance. We will combine MPI Ting’s expertise in the neuromechanics of reactive balance control and MPI Borich’s expertise in human electrophysiology to identify relationships between brain activity and motor function to improve stroke rehabilitation. Our objective is to identify cortical activity signatures that distinguish individual-, task-, and group-level differences in the engagement of cortical resources for balance control amongst young adults (Aim 1), older adults (Aim 2), and older adults with unilateral lesions due to stroke (Aim 3). We will measure electroencephalographic (EEG), electromyographic (EMG), and biomechanical signals during reactive balance recovery to support-surface translations. We propose to use both clinically feasible electrode-based analysis approaches, as well as mechanistically-important anatomically-informed functional analyses using high-density EEG in combination with structural and functional MRI scans. We hypothesize that cortical activity signatures during balance control increase in an individual-, age-, and disease-specific manner as balance task difficulty increases. Within groups, we predict individual variability in cortical activity to be explained by balance challenge, i.e., balance task difficulty normalized to step threshold, a measure of balance function. However, between groups, we predict cortical activity signatures and their relation to balance challenge will differ. Our Aims are motivated by our preliminary data that show 1) increases in N1 and beta power over leg sensorimotor regions with balance task difficulty depend on balance function in young and older adults 2) opposite relationships between sensorimotor functional connectivity and balance task difficulty in younger vs. older adults; 3) distinct aspects of balance function associated with sensorimotor vs. prefrontal-motor connectivity in older adults; and 4) sensorimotor functional connectivity in stroke survivors associated with walking function. If successful, we will identify neurophysiological indicators of balance health that will be broadly applicable across the lifespan, and across neurological and orthopedic balance disorders to significantly advance the scientific framework to enable precision-medicine strategies for personalized, mechanistic assessments and interventions to improve quality of life those with poor balance health.