Mechanisms underlying impaired postural corrections following stroke

项目摘要/摘要 预防跌倒计划的结果好坏参半，突显出需要更有效的治疗方法来应对 中风幸存者最常见的医学并发症。针对特定任务的培训，它直接针对 在跌倒过程中改善个人的反应，提供了潜力。这项提议的长期目标是 制定针对特定任务的培训，以解决中风幸存者独特的平衡挑战，即 效率高，时间效率高。在中风幸存者中实施特定任务培训计划的能力是 由于缺乏关于哪些因素和机制导致经济复苏失败的经验证据 这一群体中的平衡失调。成功复苏的基本要素(避免跌倒) 是代偿性肢体运动--迈出一步以恢复平衡或达到稳定的表面。我们最近 注意到代偿动作和惊吓动作之间的重要相似之处- 当暴露在令人震惊的刺激下时，非自愿地释放计划的运动。具体地说，令人震惊的和 在中风后，代偿性运动也有类似的缺陷，肌肉活动延迟、减少。 不适当的肌肉激活模式。因此，我们的中心假设是补偿性的赤字 中风后的运动是由惊吓引起的运动缺陷驱动的。在目标1中，我们的目标是 量化中风幸存者在平衡障碍期间的反应，确定导致 到不成功的恢复(即跌倒)。简而言之，中风幸存者将接触到一个 跑步机，同时量化稳定性测量，躯干和台阶运动学，瘫痪肢体参数，以及 肌电图仪。将评估因素对成功(避免跌倒)和失败进行分类的能力 (秋季)复苏。然后，可以在未来的特定任务培训范例中评估这些因素的可训练性 对于中风幸存者来说。在目标2中，我们将探讨导致补偿性赤字的机制。 中风幸存者的运动到手臂的扰动。我们的目标是评估赤字对惊吓的影响- 诱发运动对中风幸存者在手臂扰动期间进行有效补偿的能力。至 精确控制扰动参数并允许对偏瘫和非偏瘫肢体进行双边评估，我们 将在坐着时对受试者进行评估。在目标3中，我们将结合在目标1和目标2中学到的知识，并评估 导致跌倒的因素与所提出的机制之间的联系。我们的目标是1) 评估触发惊吓运动和成功的代偿运动之间的联系 在未受损个体的平衡挑战期间，以及2)评估以下缺陷之间的关系 惊吓诱发的运动和中风后代偿性肢体运动障碍。该计划的基本原理 建议是建立在秋季后经济复苏期间推动不成功复苏的因素和机制 笔划，以便在下一个应用程序中生成有效的特定于任务的训练范式。

PROJECT ABSTRACT/SUMMARY Fall prevention programs have had mixed results highlighting the need for more effective therapies that tackle the most common medical complication in stroke survivors. Task-specific training, which directly targets improving an individual's response during a fall, offers potential. The long-term goal of this proposal is to develop task-specific training that accounts for the unique balance challenges of stroke survivors that is both effective and time efficient. The ability to implement a task-specific training program in stroke survivors is thwarted by a lack of empirical evidence about which factors and mechanisms lead to a failed recovery during a balance disturbance in this population. An essential component of a successful recovery (avoidance of a fall) is compensatory limb movement – taking a step to regain balance or reaching to a stable surface. We recently noted important similarities between compensatory movements and startle-evoked movements – the involuntary release of planned movement when exposed to startling stimuli. Specifically, startle-evoked and compensatory movements share similar deficits following stroke – delayed, diminished muscle activity, and inappropriate patterns of muscle activation. Thus our central hypothesis is that deficits in compensatory movements post-stroke are driven by deficits in startle-evoked movements. In Aim 1, our objective is to quantify stroke survivors' response during a balance disturbance identifying the key, trainable factors that lead to unsuccessful recovery (i.e. a fall). In brief, stroke survivors will be exposed to backward translations of a treadmill while quantifying stability measures, trunk and step kinematics, paretic limb parameters, and electromyography. Factors will be assessed for their ability to classify successful (fall avoidance) and failed (fall) recoveries. These factors can then be assessed for trainability in future task-specific training paradigms for stroke survivors. In Aim 2, we will pursue identification of the mechanism driving deficits in compensatory movements to arm perturbation in stroke survivors. Our objective is to evaluate the impact of deficits in startle- evoked movement on the ability of stroke survivors to effectively compensate during an arm perturbation. To precisely control perturbation parameters and allow bilateral assessment of paretic and non-paretic limbs, we will evaluate subjects while seated. In Aim 3, we will combine knowledge gained in Aims 1 & 2 and evaluate the link between factors that contribute to falls and the mechanisms proposed. Our objectives are to 1) evaluate the link between triggering a startle-evoked movement and successful compensatory movement during a balance challenge in unimpaired individuals and 2) evaluate the relationship between deficits in startle-evoked movement and deficits in compensatory limb movements post-stroke. The rationale for the proposal is to establish both the factors and mechanisms driving unsuccessful recovery during a fall post- stroke in order to generate an effective task-specific training paradigm in the next application.