MORPHOLOGY & CONNECTIONS OF THE COCHLEAR SPIRAL GANGLION

拟议的研究解决了有关 听觉周边的发展和听觉中枢的建立 耳蜗螺旋神经节投射到 耳蜗核（CN）。 细胞化学标记技术（NB和 DiI）用于神经束示踪结合生理记录 广泛的光学和电子显微镜分析将 就业。 初步研究表明，从基底的投影 螺旋神经节到前腹分部的部分 （AVCN）在纳塔尔后经历实质性重塑 但是这些神经元的下行侧支 投射到背侧（DCN）和后腹侧（PVCN）亚核 在出生时就形成了接近成人的精致的突起。 目标 进一步的实验包括：1）为了详细地确定时间， 地形细化过程中的发展顺序的高度 对CN的每个细分的有序投影;具体到 通过以下方式表征DCN和PVCN投射的重塑 研究早期的年龄。 2)检查从心尖部的投影 耳蜗以确定CN投射的成熟与 皮质器从基底到顶端的成熟。 3)以确定 CN预测是否正常发展或是否重要 重组的发生是螺旋损伤的结果 在早期发育过程中产生的神经节。 3)以确定是否 CN投射的解剖学重塑是明显丧失的基础 电刺激诱导的频率选择性， 人工耳蜗 4)为了确定CN的开发是否 预测是活动依赖于检查的影响， 抑制一氧化氮合成和阻断听觉 神经活动 5)为了表征特定的超微结构特征， 猫耳蜗特定频率的生后发育 地点 拟议的实验将增加我们对 信息处理机制的解剖学框架 发展周边听觉系统，并将解决重要的 关于关键期和可塑性的问题。 研究 动物实验在有效性和安全性方面具有实际意义， 优化儿童人工耳蜗植入。

The proposed research addresses specific questions about the development of the auditory periphery and the establishment of the topographic organization of cochlear spiral ganglion projections to the cochlear nuclei (CN). Cytochemical labeling techniques (NB and DiI) for neuronal tract tracing combined with physiological recording and extensive light and electron microscopic analyses will be employed. Initial studies have revealed that projections from basal sectors of the spiral ganglion to the anteroventral subdivision (AVCN) undergo substantial remodeling during post natal development, but the descending collaterals of these same neurons projecting to the dorsal (DCN) and posteroventral (PVCN) subnuclei form nearly adult-like, refined projections at birth. Objectives of further experiments include: 1) To determine in detail the timing and sequence of topographic refinement during development of the highly ordered projections to each subdivision of the CN; specifically to characterize remodeling of projections to DCN and PVCN by studying earlier ages. 2) To examine projections from the apical cochlea to determine of maturation of CN projections parallels the basal-to-apical maturation of the organ of corti. 3) To determine whether CN projections develop normally or if significant reorganization occurs as a consequence of lesions of the spiral ganglion created during early development. 3) To determine whether anatomical remodeling of CN projections underlies the apparent loss of frequency selectivity induced by electrical stimulation with a cochlear implant. 4) To determine whether development of CN projections is activity dependent by examining the effects of inhibition of nitrous oxide synthesis and of blockade of auditory nerve activity. 5) To characterize specific ultrastructural features of postnatal development of the cat cochlea at specific frequency locations. The proposed experiments will increase our understanding of the anatomical framework for information processing mechanisms in the developing peripheral auditory system and will address important questions regarding critical periods and plasticity. Studies in deafened animals have practical implications regarding efficacy and optimization of cochlear implants in children.