Cerebral networks of locomotor learning and retention in older adults

衰老通常会导致行走功能的大幅下降，特别是对于需要更多时间的行走任务， 复杂，如障碍物。这部分是由于缺乏持续的复杂步行练习 （久坐的生活方式）结合与年龄相关的大脑结构缺陷和大脑网络的完整性。 神经康复有助于恢复老年人失去的行走功能，但主要和持久的 改进是难以捉摸的。神经康复的基石是运动学习，运动学习被定义为一种持久的 由于练习或经验而导致的执行运动任务的能力的变化。在大多数临床 在这种情况下，提供足够密集的运动学习干预的时间和成本需求并不 可行有必要进行研究，以制定策略，提高运动学习的步行 （“运动学习”），以提高神经康复的有效性。 本研究的目的是使用非侵入性脑刺激来增强运动学习， 研究负责行动不便的老年人运动学习的大脑网络。 我们已经证明，额叶脑区，特别是前额叶皮层，对控制复杂的 步行任务。我们的神经成像和神经调节研究也表明，前额叶皮层结构和 网络连接对于获得和巩固新的运动技能是重要的。然而，一个主要的差距 存在关于行走任务的学习。拟议的研究旨在解决这一差距。我们的试点数据 来自老年人的研究表明，前额经颅直流电刺激（tDCS）在 学习复杂的障碍行走任务有助于任务表现的多日保持。在 我们将在这项试点工作的基础上，进行一项全面的试验， 与大脑结构、功能活动和网络连接相关的机制。我们将解决 具体目标如下： 具体目标1：确定前额叶tDCS在多大程度上增强了任务练习对保持的影响 在复杂的障碍行走任务中的表现。 具体目标2：确定绩效保持与个体差异的相关程度 在基线和实践引起的大脑测量（工作记忆，灰质体积，任务， 基于前额叶活动和大脑网络隔离）。 具体目标3：研究tDCS改变静息状态网络隔离的程度。 我们预计，前额叶tDCS将增加运动学习的保留，我们的数据将提供 第一个证据表明，特定的大脑机制负责运动学习/保持在老年人与 流动性不足。这一新知识将提供一种临床可行的干预方法，并揭示 未来干预措施的机械目标，以加强运动学习和康复。

Aging often leads to substantial declines in walking function, especially for walking tasks that are more complex such as obstacle crossing. This is due in part to a lack of continued practice of complex walking (sedentary lifestyle) combined with age-related deficits of brain structure and the integrity of brain networks. Neurorehabilitation can contribute to recovery of lost walking function in older adults, but major and persistent improvements are elusive. A cornerstone of neurorehabilitation is motor learning, defined as an enduring change in the ability to perform a motor task due to practice or experience. Unfortunately, in most clinical settings, the time and cost demands of delivering a sufficiently intensive motor learning intervention is not feasible. There is a need for research to develop strategies for enhancing motor learning of walking (“locomotor learning”) in order to improve the effectiveness of neurorehabilitation. The objective of this study is to use non-invasive brain stimulation to augment locomotor learning and to investigate brain networks that are responsible for locomotor learning in mobility-compromised older adults. We have shown that frontal brain regions, particularly prefrontal cortex, are crucial to control of complex walking tasks. Our neuroimaging and neuromodulation studies also show that prefrontal cortex structure and network connectivity are important for acquisition and consolidation of new motor skills. However, a major gap exists regarding learning of walking tasks. The proposed study is designed to address this gap. Our pilot data from older adults shows that prefrontal transcranial direct current stimulation (tDCS) administered during learning of a complex obstacle walking task contributes to multi-day retention of task performance. In the proposed study we will build upon this pilot work by conducting a full scale trial that also investigates mechanisms related to brain structure, functional activity, and network connectivity. We will address the following specific aims: Specific Aim 1: Determine the extent to which prefrontal tDCS augments the effect of task practice for retention of performance on a complex obstacle walking task. Specific Aim 2: Determine the extent to which retention of performance is associated with individual differences in baseline and practice-induced changes in brain measures (working memory, gray matter volume, task- based prefrontal activity, and brain network segregation). Specific Aim 3: Investigate the extent to which tDCS modifies resting state network segregation. We anticipate that prefrontal tDCS will augment retention of locomotor learning, and that our data will provide the first evidence of specific brain mechanisms responsible for locomotor learning/retention in older adults with mobility deficits. This new knowledge will provide a clinically feasible intervention approach as well as reveal mechanistic targets for future interventions to enhance locomotor learning and rehabilitation.