MORPHOLOGY & CONNECTIONS OF THE COCHLEAR SPIRAL GANGLION

拟议的研究解决了关于 听觉外周功能的发展和功能的建立 耳蜗肌螺旋神经节投射的定位组织 耳蜗核(CN)。细胞化学标记技术(Nb和 Dii)用于结合生理记录的神经元束追踪 和广泛的光学和电子显微镜分析将是 受雇的。初步研究表明，基准面的投影 螺旋神经节向腹前亚部的分支 (AVCN)在出生后经历实质性的重塑 发育，但这些神经元的下行侧支 投射至背核(DCN)和腹后亚核(PVCN) 在出生时形成近乎成人式的精细投影。目标 进一步的实验包括：1)详细确定时间和 在高海拔地区发展过程中的地形细化顺序 对CN的每个细分进行有序投影；具体地说 通过以下方式表征DCN和PVCN的投射重构 学习更早的时代。2)检查根尖的投影 确定CN投射成熟度的耳蜗器与 Corti器官的基端到顶端的成熟。3)确定 CN预测是否正常发展或是否显著 重组是螺旋损伤的结果 神经节是在发育早期形成的。3)确定是否 CN投射的解剖重构是明显丢失的基础 由电刺激引起的频率选择性 人工耳蜗术。4)确定CN的发展是否 通过检查以下因素的影响，预测依赖于活动 一氧化二氮合成的抑制和听觉的阻断 神经活动。5)鉴定其特定的超微结构特征 猫耳蜗生后发育的特定频率 地点。 拟议中的实验将增加我们对 脑内信息处理机制的解剖学框架 发展外周听觉系统，并将解决重要的 关于关键期和可塑性的问题。研究项目： 失聪的动物在功效和 儿童人工耳蜗术式的优化。

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.