Central and peripheral mechanisms controlling human balance control

我们都看到或经历过焦虑对控制平衡能力的影响。试想一下，有人试图走过平衡木或圆木。如果横梁或圆木在地面上，人们走过去可能没有问题；然而，如果它被高高举起，许多人就会失去平衡而跌倒。有趣的是，在这两种情况下，唯一发生变化的是摔倒的威胁或后果。威胁和焦虑的影响是我们认为可能导致老年人和有平衡障碍的人出现平衡问题和跌倒的一个因素。我们的研究表明，在其他方面健康的个体中，焦虑的增加会影响他们在安静站立或对意想不到的平衡障碍做出反应时控制平衡的方式。然而，焦虑影响大脑控制平衡能力的具体方式目前尚不清楚。这项研究计划的长期目标是发现焦虑如何导致老年人和神经系统疾病患者的平衡问题。研究计划的短期目标是确定大脑和神经系统的特定区域，促进焦虑对平衡控制的影响。我们将通过让受试者站在可以升高到不同高度的物理或虚拟（使用3D虚拟现实）平台上执行平衡任务来控制焦虑。将进行一系列研究，以评估焦虑如何影响大脑的不同区域和负责向肌肉传递平衡信号的途径，调整肌肉中拉伸依赖受体的敏感性，并将相关的感觉信息传递回大脑。平衡性能将从地面反作用力、运动分析和在安静站立和平衡扰动时记录的肌肉活动来评估。从拟议的研究计划中获得的知识将用于确定与人类平衡控制中焦虑相关的变化有关的特定神经机制，并将提高我们对焦虑和平衡之间的联系如何导致平衡缺陷和跌倒的理解。

We have all seen or experienced the effect that anxiety can have on the ability to control balance. Just think of someone trying to walk across a balance beam or log. If the beam or log is on the ground, people will likely have no problems to walk across it; however, if it were raised high in the air, many people would lose their balance and fall. Interestingly, the only thing that has changed in those two conditions is the threat or consequence of a fall. The effect of threat and anxiety is one factor that we believe may contribute to balance problems and falls in older adults and people with balance disorders. Our research has shown that increased anxiety in otherwise healthy individuals can influence the way they control balance when standing quietly or reacting to an unexpected balance disturbance. However, the specific way in which anxiety may influence the brain's ability to control balance is currently unknown. The long-term goal of proposed research program is to discover how anxiety may contribute to balance problems in older adults and patients with neurological disorders. The short term goals of the research program are to identify the specific areas of the brain and nervous system that promote the effects of anxiety on balance control. We will manipulate anxiety by having subjects perform balance tasks while standing on a physical, or virtual (using 3D virtual reality), platform that can be raised to different heights. A series of studies will be performed to assess how anxiety influences different areas of the brain and pathways that are responsible for transmitting balance signals to the muscles, adjusting the sensitivity of stretch-dependent receptors in the muscles, and relaying relevant sensory information back to the brain. Balance performance will be assessed from ground-reaction forces, motion analysis and muscular activity recorded during quiet standing and balance perturbations. Knowledge developed from the proposed research program will be used to identify the specific neural mechanisms that are involved in anxiety-related changes in human balance control and will improve our understanding of how links between anxiety and balance may contribute to balance deficits and falls.