Role of vestibular information in initiation of rapid postural responses.
Role of vestibular information in initiation of rapid postural responses.
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前庭信息在快速姿势反应启动中的作用。
DOI：
10.1007/s002210050528
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发表时间：
1998
影响因子：
2
通讯作者：
Zajac,FE
中科院分区：
文献类型：
--
作者：
Runge,CF;Shupert,CL;Horak,FB;Zajac,FE
双侧前庭功能丧失的患者在不迈步的情况下难以保持平衡，尤其是在一前一后站立、在顺应性表面上站立、跨过狭窄的横梁站立或单脚站立时，尤其是在闭眼的情况下。正常人（没有感觉障碍）通过快速、主动的髋关节旋转（一种“髋关节策略”）来保持这些任务的平衡。前庭患者对短支撑表面的平移没有髋关节策略，这一点以前被认为是使用髋关节策略需要完整前庭系统的证据。然而，许多需要髋关节策略的任务会改变一个或多个重要的系统特征，例如身体的初始状态（串联站姿）、动力学（顺应性表面）或稳定性的生物力学极限（窄梁）。因此，这些任务中的平衡缺陷可能是由于在计划和执行感觉运动反应时未能考虑到这些支持表面的改变。在这项研究中，我们测试的假设，前庭信息是至关重要的触发髋关节的策略，即使在一个不变的支持表面上，这不会对系统特性的变化。我们记录了前庭患者和对照受试者的姿势反应，闭上眼睛，以不同速度的后方支持表面的翻译，在直立的立场上，一个坚定的，平坦的表面。指导受试者在可能的情况下保持平衡，不踏步。在对照受试者中，更快的平移速度（25 cm/s或更高）产生了早期髋关节扭矩（前400 ms）的一致模式（即，时髦的策略）。大多数双侧前庭功能丧失的患者对相同的平移速度有相似的扭矩反应。与我们的假设相反，我们得出结论，前庭功能是不必要的，以触发髋关节的策略。因此，我们假设，平衡赤字先前观察到的前庭患者在姿势任务，引起髋关节的策略可能是由于感觉运动的后果所施加的姿势任务在这些研究中的系统改变。两名在婴儿期失去前庭功能的年轻患者的初步结果表明，年龄、前庭功能丧失的持续时间和/或丧失的时间也可能是影响髋关节策略作为快速姿势反应的因素。
Patients with bilateral vestibular loss have difficulty maintaining balance without stepping when standing in tandem, on compliant surfaces, across narrow beams, or on one foot, especially with eyes closed. Normal individuals (with no sensory impairment) maintain balance in these tasks by employing quick, active hip rotation (a “hip strategy”). The absence of a hip strategy in vestibular patients responding to translations of a short support surface has previously been taken as evidence that the use of hip strategy requires an intact vestibular system. However, many tasks requiring hip strategy alter one or a combination of important system characteristics, such as initial state of the body (tandem stance), dynamics (compliant surfaces), or biomechanical limits of stability (narrow beams). Therefore, the balance deficit in these tasks may result from a failure to account for these support surface alterations when planning and executing sensorimotor responses. In this study, we tested the hypothesis that vestibular information is critical to trigger a hip strategy even on an unaltered support surface, which imposes no changes on the system characteristics. We recorded the postural responses of vestibular patients and control subjects with eyes closed to rearward support surface translations of varying velocity, in erect stance on a firm, flat surface. Subjects were instructed to maintain balance without stepping, if possible. Faster translation velocities (25 cm/s or more) produced a consistent pattern of early hip torque (first 400 ms) in control subjects (i.e., a hip strategy). Most of the patients with bilateral vestibular loss responded to the same translation velocities with similar torques. Contrary to our hypothesis, we conclude that vestibular function is not necessary to trigger a hip strategy. We postulate, therefore, that the balance deficit previously observed in vestibular patients during postural tasks that elicit a hip strategy may have been due to the sensorimotor consequences of the system alterations imposed by the postural tasks used in those studies. Preliminary results from two younger patients who lost vestibular function as infants indicate that age, duration of vestibular loss, and/or the timing of the loss may also be factors that can influence the use of hip strategy as a rapid postural response.