Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China; Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Department of Connectomics, Max Planck Institute for Brain Research, Frankfurt/Main, Germany.
Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
Cell Rep. 2021 Jan 5;34(1):108551. doi: 10.1016/j.celrep.2020.108551.
Recent studies reveal great diversity in the structure, function, and efferent innervation of afferent synaptic connections between the cochlear inner hair cells (IHCs) and spiral ganglion neurons (SGNs), which likely enables audition to process a wide range of sound pressures. By performing an extensive electron microscopic (EM) reconstruction of the neural circuitry in the mature mouse organ of Corti, we demonstrate that afferent SGN dendrites differ in abundance and composition of efferent innervation in a manner dependent on their afferent synaptic connectivity with IHCs. SGNs that sample glutamate release from several presynaptic ribbons receive more efferent innervation from lateral olivocochlear projections than those driven by a single ribbon. Next to the prevailing unbranched SGN dendrites, we found branched SGN dendrites that can contact several ribbons of 1-2 IHCs. Unexpectedly, medial olivocochlear neurons provide efferent innervation of SGN dendrites, preferring those forming single-ribbon, pillar-side synapses. We propose a fine-tuning of afferent and efferent SGN innervation.
最近的研究揭示了耳蜗内毛细胞 (IHC) 和螺旋神经节神经元 (SGN) 之间传入突触连接的结构、功能和传出神经支配的巨大多样性，这可能使听觉能够处理广泛的声压。通过对成熟小鼠耳蜗的神经回路进行广泛的电子显微镜 (EM) 重建，我们证明传入 SGN 树突的传出神经支配的丰富度和组成在依赖于它们与 IHC 的传入突触连接的方式上存在差异。从几个突触前带接收谷氨酸释放的 SGN 接收来自外侧橄榄耳蜗投射的传出神经支配比那些由单个带驱动的 SGN 多。除了常见的无分支 SGN 树突外，我们还发现了分支 SGN 树突，它们可以与 1-2 个 IHC 的几个带接触。出乎意料的是，内侧橄榄耳蜗神经元为 SGN 树突提供传出神经支配，偏爱形成单带、柱侧突触的 SGN。我们提出了传入和传出 SGN 支配的精细调节。
