MORPHOLOGY AND CONNECTIONS OF THE SPIRAL GANGLION

本申请中提出的实验解决了特定的问题 与出生后听觉周围的成熟有关， 目录 这些研究将提供有关 Corti器官发育的形态学和解剖学细节 耳蜗螺旋神经节细胞投射到 耳蜗核（CN）在正常和肿胀的动物。 细胞化学 神经束示踪和单纤维标记（BRP）技术 标记结合生理记录和广泛的光线， 这些研究将采用电子显微镜分析。 之间 目的如下：1）绘制出生后发育图， 螺旋神经节投射到CN利用HRP显微注射到 螺旋神经节，并确定是否精制的Islaminae 在出生时和/或成年听觉发育之前存在 阈值。2)为了确定耳蜗核投射模式 保持静止，或经历深刻的 耳毒性药物性耳聋的感觉剥夺。3)审查 慢性电刺激对组织的影响 CN投影，从而确定是否解剖重建 预测的基础是频率选择性的显着损失， 听觉中脑电刺激 被宠坏的猫4)为了确定自然活动的性质， 听觉神经的神经，从而评估它是如何 可能有助于建立正常的音调分布 CN的组织。5)为了探索罢工背后的机制， 神经节细胞和Corti器模式的差异 耳毒性药物致新生儿耳聋后观察到的退化。六、 为了表征出生后的特定超微结构特征， 猫耳蜗在成年人定义的位置的发育 基底膜的频率图。7)为了将函数 个体的、生理学特征的听觉神经的发育 具有Corti器发育形态特征的纤维. 耳蜗位置由单个标记的神经元支配。 这项拟议的工作将增加我们对解剖学的理解， 发展中国家信息处理机制框架 外周听觉系统，应该是许多人的关键兴趣， investigators. 对动物的研究解决了一些重要的问题 关于听觉系统的敏感期和可塑性， 具有实际意义的功效和优化 儿童人工耳蜗

The experiments proposed in this application address specific questions relating to the postnatal maturation of the auditory periphery in the cat. These studies will provide fundamental new information about the morphology of the developing organ of Corti and about anatomical details of the development of cochlear spiral ganglion cell projections to the cochlear nuclei (CN) in normal and deafened animals. Cytochemical labeling (BRP) techniques for neuronal tract tracing and single fiber labeling combined with physiological recording and extensive light and electron microscopic analyses will be employed in these studies. Among the objectives are the following: 1) To map the postnatal development of spiral ganglion projections to the CN utilizing HRP microinjections into the spiral ganglion, and to determine if refined isofrequency laminae are present at birth and/or prior to the development of adult auditory thresholds. 2) To determine if cochlear nucleus projection patterns remain static, or undergo topographic remodeling following profound sensory deprivation from ototoxic drug-induced deafness. 3) To examine the consequences of chronic electrical stimulation upon the organization of CN projections, and thus to determine if anatomical remodeling of projections underlies the striking loss of frequency selectivity in the auditory midbrain produced by electrical stimulation in neonatally deafened cats. 4) To determine the nature of spontaneous activity in the auditory nerve of neonatally deafened cats, and thus to assess how it might contribute to the establishment of the normal tonotopic organization of the CN. 5) To explore mechanisms underlying the striking disparity between patterns of ganglion cell and organ of Corti degeneration observed following neonatal deafening by ototoxic drugs. 6) To characterize specific ultrastructural features of postnatal development of the cat cochlea at locations defined by the adult frequency map of the basilar membrane. 7) To correlate the functional development of individual, physiologically-characterized auditory nerve fibers with the morphologic features of organ of Corti development at cochlear locations innervated by individual labeled neurons. This proposed work will increase our understanding of the anatomical framework for information processing mechanisms in the developing peripheral auditory system and should be of critical interest to many investigators. Studies in deafened animals address important questions regarding sensitive periods and plasticity in the auditory system, and have practical implications regarding the efficacy and optimization of cochlear implants in children.