Stretch Reflex Contributions to Multijoint Coordination

牵张反射对多关节协调的贡献

• 批准号: 7019224
• 负责人: ERIC JON PERREAULT
• 金额: $ 26.25万
• 依托单位: REHABILITATION INSTITUTE OF CHICAGO D/B/A SHIRLEY RYAN ABILITYLAB
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7019224
• 关键词: clinical research; joints; limbs; muscle; posture; reflex; stretch reflex

DESCRIPTION (provided by applicant): Abnormal interjoint coordination is a hallmark of neuropathologies such as stroke and spinal cord injury, and there is evidence that changes in stretch reflex function may contribute to this discoordination. Understanding the significance of these changes and how they might be reversed or reduced through rehabilitation is best done in the context of the unimpaired state. However, there is little information regarding the role of stretch reflexes in the unimpaired control of multijoint movement and posture. Rather, most human studies have focused on the stretch response to single joint perturbations, which allow for unambiguous regulation of muscle length, but do not address the complexities of real perturbations and real movements involving multiple muscles acting in multiple degrees of freedom. This purpose of this grant is to examine stretch reflex contributions to multijoint coordination in the unimpaired human arm. Specifically we will determine if the muscle activation patterns generated in response to whole limb perturbations arise from neurally-mediated, intermuscular (heteronymous) connections or if they simply represent the autogenic (homonymous) responses of individual muscles linked via the skeleton. In addition, the functional consequences of these actions will be addressed by quantifying the mechanical impact of any observed reflex actions. Our Aims are: 1) To examine the heteronymous reflexes connecting the elbow and shoulder by applying single joint perturbations to a single joint, and recording the changes in muscle activity elicited at both joints. These results will provide a "model-free" assessment of heteronymous linkages. 2) To examine the relative contributions of homonymous and heteronymous stretch reflex pathways in coordinating the response to whole limb perturbations. This will be investigated using a 3DOF robot to perturb limb posture and a 3D biomechanical model to estimate the resulting muscle length changes. Changes in muscle activation that are not directly linked to homonymous length changes are likely to represent the output of heteronymous pathways. 3) To examine the influence of reflexively evoked changes in muscle activity on the regulation of multijoint mechanics. The first two Aims are important for assessing the existence and connectivity of stretch reflex responses, but alone do not establish their functional consequences. The latter requires an assessment of how reflex responses influence the mechanical properties of a limb. This will be accomplished using nonlinear system identification techniques to estimate stretch reflex contributions to multijoint impedance. This study will be the first to investigate the role of multijoint stretch reflexes for coordinating arm posture in the 3DOF relevant to normal function. Our results will provide the essential basis for our further investigations into abnormal reflex function following stroke and will elucidate the degree to which spinal mechanisms should be targeted by rehabilitation interventions.

描述（由申请人提供）：关节间协调异常是神经病理学的标志，如中风和脊髓损伤，有证据表明牵张反射功能的变化可能导致这种失调。理解这些变化的意义以及如何通过康复来逆转或减少这些变化，最好是在未受损状态的背景下进行。然而，很少有关于牵张反射在多关节运动和姿势的未受损控制中的作用的信息。相反，大多数人类研究都集中在对单个关节扰动的拉伸反应上，这允许明确地调节肌肉长度，但没有解决涉及多个肌肉在多个自由度上作用的真实的扰动和真实的运动的复杂性。这项研究的目的是研究牵张反射对未受损人类手臂多关节协调的贡献，具体来说，我们将确定整个肢体扰动产生的肌肉激活模式是否来自神经介导的肌间（异源性）连接，或者它们是否仅仅代表通过骨骼连接的单个肌肉的自生（同源性）反应。此外，将通过量化任何观察到的反射动作的机械影响来解决这些动作的功能后果。我们的目标是：1）通过对单个关节施加单个关节扰动并记录在两个关节处引起的肌肉活动的变化来检查手肘和肩的异向反射。这些结果将提供一个“无模式”的异质性联系的评估。2)目的：研究同侧和异侧牵张反射通路在协调对全肢扰动反应中的相对作用。这将使用3DOF机器人来扰动肢体姿势和3D生物力学模型来估计由此产生的肌肉长度变化。与同源长度变化没有直接联系的肌肉激活变化可能代表了异源途径的输出。3)检查反射诱发的肌肉活动变化对多关节力学调节的影响。前两个目的对于评估牵张反射反应的存在和连接性很重要，但单独不能确定其功能后果。后者需要评估反射反应如何影响肢体的机械性能。这将使用非线性系统识别技术来估计牵张反射对多关节阻抗的贡献。这项研究将是第一个调查的作用，多关节伸展反射协调手臂姿势在3DOF相关的正常功能。我们的研究结果将为我们进一步研究中风后的反射功能异常提供必要的基础，并将阐明康复干预应针对脊柱机制的程度。