Mechanisms underlying impaired postural corrections following stroke

描述：跌倒预防计划的结果好坏参半，凸显了需要更有效的治疗方法来解决中风幸存者最常见的医学并发症。针对特定任务的培训，其直接目标是提高个人在跌倒时的反应能力，它提供了潜力。这项建议的长期目标是开发针对中风幸存者独特的平衡挑战的特定任务培训，既有效又节省时间。在中风幸存者中实施特定任务训练计划的能力受到缺乏经验证据的阻碍，因为缺乏经验证据表明，在这一人群的平衡障碍期间，哪些因素和机制导致康复失败。成功恢复(避免跌倒)的一个重要组成部分是代偿性肢体运动--迈出一步以恢复平衡或达到稳定的表面。PI最近注意到了代偿性运动和惊吓引起的运动之间的重要相似之处--当暴露在令人震惊的刺激下时，计划的运动不由自主地释放。具体地说，惊吓引起的运动和代偿性运动在中风后的延迟、肌肉活动减少和不适当的肌肉激活模式后具有相似的缺陷。因此，PI的中心假设是，中风后代偿性运动的缺陷是由惊吓诱发的运动缺陷驱动的。在目标1中，目标是量化中风幸存者在平衡障碍期间的反应，确定导致不成功康复(即摔倒)的关键、可训练的因素。简而言之，中风幸存者将接触到跑步机的反向平移，同时量化稳定性测量、躯干和台阶运动学、偏瘫肢体参数和肌电图。将评估这些因素对成功(避免跌倒)和失败(跌倒)恢复的分类能力。然后，可以在未来针对中风幸存者的特定任务训练范例中评估这些因素的可训练性。在目标2中，私人投资总监将探讨导致赤字的机制。 中风幸存者对手臂扰动的代偿性运动。目的是评估惊吓运动缺陷对中风幸存者有效地 在手臂扰动期间进行补偿。为了精确控制扰动参数，并允许对瘫痪和非瘫痪肢体进行双边评估，PIS将在坐着时对受试者进行评估。在目标3中，绩效指标将结合在目标1和目标2中获得的知识，并评估导致跌倒的因素与所提出的机制之间的联系。其目的是1)评估在未受损个体的平衡挑战中触发惊吓诱发运动和成功的代偿性运动之间的联系，以及2)评估中风后惊厥诱发运动缺陷和代偿性肢体运动缺陷之间的关系。该建议的基本原理是建立在中风后跌倒期间导致不成功恢复的因素和机制，以便在下一次应用中产生有效的针对任务的训练范例。

DESCRIPTION: 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 thwarte 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. The PIs 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 the PIs' central hypothesis is that deficits in compensatory movements post-stroke are driven by deficits in startle-evoked movements. In Aim 1, the 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 stabilit 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) recoveies. These factors can then be assessed for trainability in future task-specific training paradigms for stroke survivors. In Aim 2, the PIs will pursue identification of the mechanism driving deficits in compensatory movements to arm perturbation in stroke survivors. The 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, the PIs will evaluate subjects while seated. In Aim 3, the PIs will combine knowledge gained in Aims 1 & 2 and evaluate the link between factors that contribute to falls and the mechanisms proposed. The 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.