Multisensory Integration and Human Postural Control

描述（由申请人提供）：本研究的长期目标是了解神经系统如何融合来自多个感觉系统的信息来控制直立姿势。在病人和老年人中，自适应地选择和重新权衡可选择的方向参考的能力被认为是姿势控制的关键因素。尽管多感官重加权很重要，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，同时操纵两种感觉输入（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制模型来确定姿势摇摆的哪些特征可以：i)归因于估计或控制；ii)区分用于多感官重加权的不同估计机制。具体目标是：

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.