Development & Connections of Cochlear Spinal Ganglion

超出所提供的空间。 本研究提出了关于耳蜗发育和螺旋神经节投射到耳蜗核（CN）的地形组织的建立的具体问题。将采用细胞化学标记技术（NB和Dil）结合电生理记录和广泛的定量光镜和电镜分析进行神经束示踪。我们最近的研究表明，从螺旋神经节的基底部门的CN的每个细分的预测进行显着细化在出生后的早期发展。投射到前腹分区（AVCN）是超过50%，在新生儿比成人更广泛的CN大小归一化时，这些相同的神经元投射到背侧（DCN）和后腹（PVCN）分区的下行侧支是30%，比他们的成人同行。实验的目的包括：（1）进一步研究在妊娠晚期和出生后早期发育过程中，CN每个分区的投影的时间和顺序的细节。2)检查耳蜗顶端的投射，以确定其CN投射的成熟是否与Corti器的基底至顶端的成熟平行。3)完成新生儿耳聋对成年后严重听觉剥夺后CN投射特异性影响的定量研究。4)确定CN投射是否正常发育，或者是否由于早期发育期间螺旋神经节的限制性病变而发生显著重组。5)确定CN投射的解剖学重构是否是慢性脑内电刺激诱导的频率选择性明显丧失的基础。6)通过观察螺旋神经节内自发活动的性质，探讨听神经投射正常发育的机制。7)表征猫Corti器官在特定频率位置的出生后发育的选定超微结构特征。拟议的实验将增加我们的理解的解剖框架的信息处理机制在发展中的听觉系统，并将解决重要的问题，关键时期和可塑性。此外，拟在麻醉动物中进行的研究对儿童人工耳蜗的应用具有实际意义。性能现场=

EXCEED THE SPACE PROVIDED. This proposed research addresses specific questions regarding the development of the cochlea and the establishment of the topographic organization of spiral ganglion projections to the cochlear nuclei (CN). Cytochemical labeling techniques (NB and Dil) for neuronal tract tracing combined with electrophysiological recording and extensive quantitative light and electron microscopic analyses will be employed. Our recent studies have shown that projections from basal sectors of the spiral ganglion to each subdivision of the CN undergo significant refinement during early postnatal development. Projections to the anteroventral subdivision (AVCN) are more than 50% broader in neonates than in adults when normalized for CN size, and the descending collaterals of these same neurons projecting to the dorsal (DCN) and posteroventral (PVCN) subdivisions are 30% broader than their adult counterparts. Goals of proposed experiments include: 1) To further investigate the details of timing and sequence of topographic refinement during late gestation and early postnatal development of the projections to each subdivision of the CN. 2) To examine projections from the apical cochlea to determine if maturation of its CN projections parallels the basal-to-apical maturation of the organ of Corti. 3) To complete quantitative studies of the effects of neonatal deafening upon the specificity of CN projections examined in adulthood after a lifetime of severe auditory deprivation. 4) To determine whether CN projections develop normally or if significant reorganization occurs as a consequence of restricted lesions of the spiral ganglion created during early development. 5) To determine whether anatomical remodeling of CN projections underlies the apparent loss of frequency selectivity induced by chronic intracochlear electrical stimulation. 6) To explore the mechanisms which underlie normal development of the auditory nerve projections by examining the nature of spontaneous activity (if any) in spiral ganglion. 7) To characterize selected ultrastructural features of postnatal development of the cat organ of Corti at specific frequency locations. The proposed experiments will increase our understanding of the anatomical framework for information processing mechanisms in the developing auditory system and will address important questions regarding critical periods and plasticity. In addition, studies to be conducted in deafened animals have practical implications regarding application of cochlear implants in children. PERFORMANCE SITE ========================================Section End===========================================