CELLULAR MECHANISMS OF THE VESTIBULAR SYSTEM

我们的长期目标是了解细胞机制， 前庭神经传入神经的放电特性。 为此， 已经开发了海龟后嵴的体外制备。 其优点是：1）输入放电特性 在体外制备和完整的，呼吸 动物 2)I型毛细胞仅限于中央区域，它们 构成了这个区域的毛细胞的绝大多数， 由具有独特生理特性的传入神经支配。 在 一个类似的静脉，bouton传入不同，在他们的生理 这些特性支配着外围区的不同部分。 因此通过 研究从不同区域采集的毛细胞， 可能将毛细胞和传入神经的生理学联系起来 使它们活跃起来。 3)传出神经的电刺激产生 一些传入神经兴奋，另一些则抑制。 由于两 各种传入神经支配神经上皮的不同部分， 研究从特定区域提取的毛细胞应该使我们能够 决定了这两种传出动作的细胞基础。 4)头发 来自该器官的细胞相对容易分离和表征 全细胞密封记录。 有三个具体目标：1）完成前庭的研究- 神经放电的体外制备。 传入的特点是 他们对头部旋转的反应， 传出纤维的电刺激，以及 其外围终端的形态。 2)为了表征I型 和II型毛细胞，分离自特定区域的 神经上皮，就其电压和离子敏感电流而言， 以及传出递质乙酰胆碱诱发的电流 （乙酰胆碱）。 3)将研究扩展到乌龟椭圆囊斑 因为这个终末器官为一些计划中的研究提供了优势， 在接下来的几年里。 拟议的研究旨在对两个问题作出贡献。 什么 是I型毛细胞和它们的花萼的独特功能 结局？ 神经元的传出调节功能是什么？ 前庭终器 这些问题对于理解 前庭迷路的运作在健康和疾病。

Our long-term goal is to understand the cellular mechanisms determining the discharge properties of vestibular-nerve afferents. To this end, an in vitro preparation of the turtle posterior crista has been developed. Its advantages are: 1) Afferent discharge properties are indistinguishable in the in vitro preparation and in intact, respiring animals. 2) Type I hair cells are restricted to a central zone, they make up the large majority of hair cells in this zone, and they are innervated by afferents having distinctive physiological properties. In a similar vein, bouton afferents differing in their physiological properties innervate distinct parts of the peripheral zone. Hence, by studying hair cells harvested from the different regions, it should be possible to correlate the physiology of hair cells and of the afferents innervating them. 3) Electrical stimulation of efferents produces excitation in some afferents and inhibition in others. Since the two kinds of afferents innervate distinct parts of the neuroepithelium, a study of hair cells drawn from specific regions should allow us to determine the cellular basis for both kinds of efferent actions. 4) Hair cells from this organ are relatively easy to isolate and to characterize with whole-cell tight-seal recordings. There are three specific aims: 1) To complete studies of vestibular- nerve discharge in the in vitro preparation. Afferents are characterized in terms of their responses to head rotations, their responses to electrical stimulation of efferent fibers, and the location and morphology of their peripheral terminations. 2) To characterize type I and type II hair cells, isolated from specific regions of the neuroepithelium, in terms of their voltage- and ion-sensitive currents, as well as the current evoked by the efferent transmitter, acetylcholine (ACh). 3) To extend the studies to the utricular macula of the turtle because this end organ offers advantages for some of the research planned for the next several years. The proposed studies are intended to contribute to two questions. What are the distinctive functions of type I hair cells and their calyx endings? What is the function of the efferent regulation of the vestibular end organs? The questions are of importance in understanding the operation of the vestibular labyrinth in health and disease.