Vestibular Contributions to Estimated Head Motion and Orientation

描述（由申请人提供）：前庭迷宫提供的有关头部运动和方向的信息受到几个特征的限制，但在前庭刺激期间，大脑仍然能够产生相对准确的感知和眼动反应。前庭系统必须处理的一个主要问题是神经处理的各个方面所固有的噪声。在这个提议中，我们将使用几种新技术（包括非人灵长类动物的前庭心理物理学，半规管传入的高频电刺激，前庭-眼反射（VOR）阈值和前庭中央噪声的测量）来研究噪声如何影响负责前庭介导的眼球运动和知觉反应的中央加工。更具体地说，我们提出了三个假设，我们将在三个特定的目标中进行测试，重点关注大脑优化感知和眼动反应的能力，尽管迷宫提供的信息有限。在前两个具体目标中，我们将通过使用非常高频的电刺激管道壶腹神经叠加在正常管道传入信号上，来改变管道传入信号的噪声量。我们将研究椎管旋转输入上的噪声如何影响知觉和眼动反应，并预测当噪声增加时，大脑中的速度存储积分器将变得不那么有效（目的1），并且低频平移作为倾斜的误解将会加剧（目的2）。在具体目标3中，我们将研究前庭外周消融增加中央前庭噪声的假设，通过氨基糖苷诱导不同程度的前庭外周功能减退，并测量VOR的变化和前庭噪声的行为测量，基于头部静止时注视点状目标时眼速度方差的变化。总之，这些实验将有助于回答关于前庭信息如何被集中处理的长期和基本问题，这项工作不仅将提高对正常前庭生理学的理解，而且可能有助于阐明外周和中枢前庭系统疾病引起的异常知觉和眼动反应的机制。

DESCRIPTION (provided by applicant): The information about head motion and orientation provided by the vestibular labyrinth is constrained by several features, but the brain is still abl to generate relatively accurate perceptual and eye movement responses during vestibular stimulation. One major problem the vestibular system must deal with is the noise inherent in all aspects of neural processing. In this proposal we will use several novel techniques (including vestibular psychophysics in non-human primates, high-frequency electrical stimulation of semicircular canal afferents, and measures of the vestibulo-ocular reflex (VOR) threshold and central vestibular noise) to investigate how noise affects the central processing that is responsible for vestibular-mediated eye movement and perceptual responses. More specifically, we propose three hypotheses which we will test in three specific aims that focus on the brain's ability to optimize perceptual and eye movement responses despite the limitations in the information provided by the labyrinth. In the first two specific aims, we will vary the amount of noise on the canal afferent signals by using very high-frequency electrical stimulation of the canal ampullary nerves superimposed on the normal canal afferent cues. We will investigate how noise on the canal rotational inputs affects perceptual and eye movement responses, and predict that when the noise increases the velocity storage integrator in the brain will become less effective (aim 1) and that the misperception of low-frequency translation as tilt will be accentuated (aim 2). In specific aim 3, we will investigate the hypothesis that peripheral vestibular ablation increases central vestibular noise by inducing different degrees of peripheral vestibular hypofunction with aminoglycosides and measuring changes in the VOR and in a behavioral measure of vestibular noise, based on changes in the variance of eye velocity during fixation of a punctate target with the head stationary. In sum, these experiments will help answer longstanding and fundamental questions about how vestibular information is processed centrally, and this work will not only improve understanding of normal vestibular physiology but may also help elucidate the mechanisms responsible for the abnormal perceptual and eye movement responses that occur with disorders of the peripheral and central vestibular system.