Function of Vestibular-Nerve Afferent Types

描述（由申请人提供）：前庭系统负责收集头部在空间中的位置和运动信息。这些信息通过前庭脊髓反射的作用来维持姿势，并通过前庭眼反射（VOR）来稳定凝视。由于前庭输入脑干的中断而导致这些反射功能障碍可导致诸如梅尼埃病和氨基糖苷中毒等病理，并可能导致致残性眩晕和不平衡。在哺乳动物中，有三种类型的前庭神经传入神经元将这些信号从前庭外围传递到脑干，但这些不同类别的目的尚不清楚。基于它们的灵敏度和基线放电模式，它们被称为“定期放电”、“不规则放电”和“低增益不规则放电”。

DESCRIPTION (provided by applicant): The vestibular system is responsible for collecting information about the head's position and movement in space. This information is used to maintain posture through the actions of the vestibulospinal reflexes and to stabilize gaze by means of the vestibulo-ocular reflex (VOR). Dysfunction of these reflexes due to disruption of vestibular input to the brainstem can lead to pathologies such as Meniere's disease and aminoglycoside toxicity and may bring about disabling vertigo and disequilibrium. In mammals, three types of vestibular-nerve afferent neurons carry these signals from the vestibular periphery to the brainstem, but the purpose for these separate classes is not known. Based on their sensitivity and baseline discharge patterns, they have been termed "regularly discharging," "irregularly discharging," and "low-gain irregularly discharging." Indirect evidence suggests that these afferent types may be differentially affected by various pathologic processes. The studies proposed here aim to define the contribution of irregular afferents to the VOR by reversibly stimulating or inhibiting their contribution to the vestibulo-ocular reflex during high-frequency sinusoidal rotations as well as short transient motions of the head. The dynamics of irregular afferents suggest that their contribution to the VOR may be particularly important under these previously untested conditions. Techniques of signal theory will be used, based on the responses of individual afferents to sharp movements, to determine the relative information carrying capacity of neurons over the short latencies (< 10 ms) allowed by the VOR. A model of vestibular-nerve afferents that predicts neural responses to high-frequency and transient head motion will be developed from the data collected. Findings from this study will allow better understanding of pathologies of the peripheral vestibular system.