Multisensory Integration and Human Postural Control

描述(申请人提供)：这项研究的长期目标是了解神经系统如何融合来自多个感官系统的信息来控制直立姿势。在患者和老年人群中，自适应地选择和重新加权另一种定向参考的能力被认为是姿势控制的关键因素。尽管多感官加权很重要，但人们对它是如何实现的知之甚少。我们开发了一种新的实验范式，可以同时操作两种感觉输入(视觉和触觉)来探索多感觉整合的特性。同时，我们开发了一种独特的两步建模方法，使用时间序列技术和机械模型来确定姿势摆动的哪些特征可以：i)归因于估计或控制；以及ii)区分用于多感觉重新加权的不同估计机制。具体目标是： 研究姿势摆动的感觉耦合和重加权特性。三个实验将准确地定义感官通道(视觉和触觉)提供的信息，以及这些通道如何通过重新加权进行交互。我们假设：a)强速度耦合和弱位置耦合；b)跨频率的均匀重新加权；以及c)取决于感觉输入的均方根速度的重新加权； 描述多感官重加权的动力学特征。神经系统在一个通道内和不同通道之间重新加权感觉信息的时间尺度尚不为人所知。两个实验将通过：1)在试验中添加或删除感觉通道；2)在试验中改变环境运动的幅度来研究重新加权动力学。我们假设，重新加权是：i)一个相对缓慢的过程；ii)依赖于新增加的感觉输入的幅度；以及 生病了。目的：确定双侧前庭功能丧失(BVL)患者和健康受试者的评估和控制的差异。前庭信息的丢失是否会影响估计和/或控制，目前尚不清楚。通过使用视觉和触摸输入以及固定或参考摇摆的支撑面的两个实验，比较BVL和健康受试者姿势摇摆动态特征的差异。我们的假设是，前庭功能的丧失影响了估计的性质，而不是控制。 这一建议的含义是：1)加强BVL患者的康复；2)开发一个明确将潜在生理子系统与姿势控制联系起来的机械模型。未来的工作将用类似的技术解决其他患者群体，以确定他们平衡赤字的基础。

DESCRIPTION (provided by applicant): The long-term goal of this research is to understand how the nervous system fuses information from multiple sensory systems for the control of upright stance. The ability to select and reweight alternative orientation references adaptively is considered a critical factor for postural control in patient and elderly populations. Despite the importance of multisensory reweighting, little is known about how it is achieved. We have developed a new experimental paradigm that simultaneously manipulates two sensory inputs (vision and touch) to probe the properties of multisensory integration. In parallel, we have developed a unique two-step modeling approach using time series techniques and mechanistic models to determine which characteristics of postural sway can: i) be attributed to estimation or control; and ii) distinguish different mechanisms of estimation used for multisensory reweighting. The specific aims are: I. To characterize sensory coupling and reweighting properties of postural sway. Three experiments will precisely define the information that sensory modalities (vision & touch) provide and how the modalities interact through reweighting. We hypothesize: a) strong velocity coupling and weak position coupling; b) uniform reweighting across frequency; and c) reweighting that is dependent upon the root mean square (RMS) velocity of sensory input; II. To characterize the dynamics of multisensory reweighting. The time scale over which the nervous system reweights sensory information within a modality and between modalities is not well known. Two experiments will investigate reweighting dynamics by: 1) adding or removing a sensory modality within a trial; 2) changing the amplitude of environmental motion within a trial. We hypothesize that reweighting is: i) a relatively slow process; and ii) dependent upon the amplitude of a newly added sensory input; and Ill. To determine how estimation and control differ in individuals with bilateral vestibular loss (BVL) and healthy subjects. It is not known whether the loss of vestibular information influences estimation and/or control. Differences in the dynamic characteristics of postural sway will be compared in BVL and healthy subjects with two experiments using visual and touch input and fixed or sway-referenced support surfaces. Our hypothesis is that the loss of vestibular function influences properties of estimation, rather than control. The implications of this proposal are: 1) to enhance rehabilitation of individuals with BVL; and 2) to develop a mechanistic model that will explicitly link underlying physiological subsystems to postural control. Future work will address other patient populations with similar techniques to determine the basis of their balance deficits.