Neuromechanical Modeling of Postural Responses

描述(由申请人提供)：由于失去平衡导致的跌倒是老年人受伤和死亡的主要原因，也是一种广泛的神经、肌肉骨骼和认知缺陷的衰弱症状。然而，由于许多神经和肌肉骨骼因素可能导致平衡障碍--或者相当于代偿策略--临床医生往往难以评估平衡障碍的严重程度，或确定其根本原因。本项目的目的是了解在站立平衡控制过程中，有助于姿势稳定的前馈和反馈神经机械元件的调节原理。我们选择在一次数据收集的时间框架内，研究神经系统可以快速调节或选择的神经机械元件。我们将前馈神经机械元件定义为那些在预期姿势扰动时调整肌肉骨骼系统的内在机械稳定性的元件，如姿势构型和姿势肌肉张力。我们将反馈神经机械元件定义为那些在姿势扰动后反应性激活肌肉的元件，包括任务级反馈增益、肌肉协同效应和脊髓反射。我们假设前馈和反馈神经机械元件被调制以实现诸如稳定性、可操作性、能量最小化或对不确定性的稳健性等隐含的性能目标。不同的表现目标可以解释在不同试验、不同个体、不同背景或不同运动缺陷之间观察到的运动变化。我们预测，神经机械元素的不同组合可能会产生定性上相似的运动，但在功能和能量上却会产生不同的结果。在目标1中，我们将研究用于站立平衡控制的前馈和反馈神经机械元件之间的相互作用；在目标3中，在完整动物的短期和长期姿势适应期间，我们将研究用于站立平衡控制的前馈和反馈神经机械元件之间的相互作用。在目标2中，我们将使用姿势控制的神经机械模型来确定功能和能量成本以及可能驱动健康和疾病的姿势适应的约束之间的权衡。这项建议继续发展我们的一般科学框架，朝着我们的长期目标发展，即了解、诊断和预测有平衡缺陷和一般运动障碍的个人的最佳运动功能。 公共卫生相关性：失去平衡导致跌倒是导致老年人受伤死亡的主要原因。由于一些神经和肌肉骨骼的缺陷，可能会发生失去平衡导致某人摔倒的情况。我们将确定特定的神经损伤如何改变平衡控制中微妙但可测量的变化。我们还开发了计算机模拟和分析工具，最终可能帮助医生预测如何最好地治疗平衡障碍。

DESCRIPTION (provided by applicant): Falls due to a loss of balance are a primary cause of injury and death in the elderly, and a debilitating symptom of a wide range of neurological, musculoskeletal, and cognitive deficits. However, because many neural and musculoskeletal elements can contribute to balance impairments - or equivalently to compensatory strategies - it is often difficult for clinicians to evaluate the severity of balance impairments, or to identify their underlying causes. The objective of this project is to understand the principles governing the modulation of feedforward and feedback neuromechanical elements contributing to postural stability during standing balance control. We have chosen to study the neuromechanical elements that can be rapidly modulated or selected by the nervous system, within the time frame of one session of data collection. We define feedforward neuromechanical elements to be those that adjust the intrinsic mechanical stability of the musculoskeletal system in anticipation of a postural perturbation, such as postural configuration and postural muscle tone. We define feedback neuromechanical elements to be those that activate muscles reactively following postural perturbations, and include task-level feedback gains, muscle synergies, and spinal reflexes. We hypothesize that the feedforward and feedback neuromechanical elements are modulated to achieve implicit performance goals such as stability, maneuverability, energy minimization, or robustness to uncertainty. Differing performance goals could explain variations in movement observed across trials, across individuals, across contexts, or across motor deficits. We predict that various combinations of neuromechanical elements may produce qualitatively similar movements, and yet quantitatively different functional and energetic consequences. We will study interactions between feedforward and feedback neuromechanical elements for standing balance control in normal and neurologically-impaired cats in Aim 1; during short- and long- term postural adaptations in intact animals in Aim 3. In Aim 2, we will identify tradeoffs between functional and energetic costs and constraints that may drive postural adaptations in both health and disease using neuromechanical models of postural control. This proposal continues our development of a general scientific framework toward our long-term goal of understanding, diagnosing, and predicting optimal motor function in individuals with balance deficits, and motor impairments in general. PUBLIC HEALTH RELEVANCE: Falls due to a loss of balance are the leading cause of injury leading to death in older adults. Loss of balance causing someone to fall can happen due to a number of neurological and musculoskeletal deficits. We will identify how specific neurological impairments alter subtle, but measurable changes in balance control. We also develop computer simulation and analysis tools that may eventually help physicians predict how best to treat balance impairments.