COCHLEAR NERVE DEVELOPMENT

这项研究将探讨出生后的结构和功能的变化， 哺乳动物耳蜗神经元，是听觉成熟的基础。 的 耳蜗神经支配模式的发展将在一个年龄- 使用体内标准和新设计的新生沙鼠分级系列 体外辣根过氧化物酶示踪方法应用于完整和 严重切除耳蜗 大鼠耳蜗神经元轴发育的平行体外研究 长时间的器官型培养的沙鼠Corti器官将检查 耳蜗发育中神经元竞争作用 传入和传出神经在耳蜗毛细胞成熟形态形成中的作用 神经支配 引导形成和修剪的超微结构事件 耳蜗神经元及其靶毛细胞将在这两个研究 完整和培养耳蜗的连续重建选择的HRP- 使用高压电子显微镜（HVEM）标记的传入末梢。 耳蜗神经元声反应特性的生后变化 将在耳蜗螺旋内的特定部位使用新的 新生沙鼠螺旋神经节细胞记录法 这个国家有超过25万的儿童有听力障碍 因为某种先天性感觉神经性听力损失 拟议 研究应提供关键的规范性数据， 了解疾病改变发展的机制， 听觉周边的结构和功能。

This study will examine the postnatal changes in structure and function of mammalian cochlear neurons which underlie the maturation of hearing. The development of cochlear innervation patterns will be charted in an age- graded series of neonatal gerbils using standard in vivo and newly devised in vitro Horseradish peroxidase tract-tracing methods applied to intact and acutely-excised cochleae. Parallel in vitro studies of the development of cochlear neuron arbors in long-term organotypic cultures of the gerbil organ of Corti will examine the potential role of neuronal competition between developing cochlear afferents and efferents in sculpting a mature pattern of cochlear hair cell innervation. The ultrastructural events which guide the formation and pruning of cochlear neuron arbors with their target hair cells will be studied in both intact and cultured cochleae by serial reconstruction of selected HRP- labeled afferent terminals using high voltage electron microscopy (HVEM). Postnatal changes in the response properties of cochlear neurons to sound will be explored at specific sites within the cochlear spiral using a new spiral ganglion cell recording approach in neonatal gerbils. Over a quarter of a million children in this country are hearing impaired due to some form of congenital sensorineural hearing loss. The proposed studies should provide crucial normative data which are required for understanding the mechanisms by which disease alters the development of structure and function in the auditory periphery.