Vestibular Contributions to Estimated Head Motion and Orientation

描述（由申请人提供）：由前庭迷路提供的关于头部运动和定向的信息受到几个特征的约束，但是大脑仍然能够在前庭刺激期间产生相对准确的感知和眼睛运动响应。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固有的噪声。在这项提案中，我们将使用几种新的技术（包括前庭心理物理学在非人类灵长类动物，高频电刺激半规管传入，前庭眼反射（VOR）阈值和中央前庭噪声的措施），以调查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处理。更具体地说，我们提出了三个假设，我们将测试在三个特定的目标，专注于大脑的能力，优化感知和眼球运动的反应，尽管迷宫提供的信息的限制。在前两个具体的目标，我们将通过使用非常高的频率电刺激的运河壶腹神经叠加在正常的运河传入线索上的运河传入信号的噪声量。我们将研究如何噪声的运河旋转输入影响知觉和眼动反应，并预测，当噪声增加的速度存储积分器在大脑中将变得不那么有效（目标1）和低频平移的错觉倾斜将加重（目标2）。在具体目标3中，我们将研究外周前庭消融通过氨基糖苷类诱导不同程度的外周前庭功能减退并测量VOR和前庭噪声行为测量的变化来增加中枢前庭噪声的假设，该变化基于头部静止固定点状目标期间眼速方差的变化。总之，这些实验将有助于回答关于前庭信息如何集中处理的长期存在的基本问题，这项工作不仅将提高对正常前庭生理学的理解，而且还可能有助于阐明外周和中枢前庭系统疾病发生的异常感知和眼动反应的机制。

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.