Spatiotemporal Analysis of Cochlear Nucleus Innervation by Spiral Ganglion Neurons that Serve Distinct Regions of the Cochlea.
Spatiotemporal Analysis of Cochlear Nucleus Innervation by Spiral Ganglion Neurons that Serve Distinct Regions of the Cochlea.
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DOI：
10.1016/j.neuroscience.2020.08.029
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发表时间：
2020-10-15
期刊：
影响因子：
3.3
通讯作者：
Yu WM
中科院分区：
文献类型：
--
作者：
Scheffel JL;Mohammed SS;Borcean CK;Parng AJ;Yoon HJ;Gutierrez DA;Yu WM
耳蜗神经元根据其对不同声音频率（称为神经元的特征频率）的敏感性，以张力异位的方式支配脑干耳蜗核。目前尚不清楚这些具有不同特征频率的神经元是否使用不同的策略来支配耳蜗核。在这里，我们使用遗传方法对传递不同特征频率的螺旋神经节神经元（sgn）及其听觉神经纤维（anf）进行差异标记。我们发现，提供耳蜗不同区域的SGN群体在耳蜗声位图形成过程中采用不同的细胞策略来靶向和支配耳蜗核中的神经元。表现出高特征频率的anf在初始超调时，会对大面积的目标进行采样，然后再优化其与正确目标的连接，而表现出低特征频率的光纤在初始定位时更准确，并进行最小的目标采样。此外，与周围突起相似，anf的中心突起沿张力轴呈梯度发展，预期高频anf的生长和分支比预期低频anf早2天左右开始。高频anf和低频anf的突触发生过程相似，但低频anf形成更小的终球突触末梢的比例更高。这些观察结果揭示了细胞机制的多样性，听觉神经元将成为功能上不同的，在听觉图形成过程中用来支配它们的目标。
Cochlear neurons innervate the brainstem cochlear nucleus in a tonotopic fashion according to their sensitivity to different sound frequencies (known as the neuron's characteristic frequency). It is unclear whether these neurons with distinct characteristic frequencies use different strategies to innervate the cochlear nucleus. Here, we use genetic approaches to differentially label spiral ganglion neurons (SGNs) and their auditory nerve fibers (ANFs) that relay different characteristic frequencies. We found that SGN populations that supply distinct regions of the cochlea employ different cellular strategies to target and innervate neurons in the cochlear nucleus during tonotopic map formation. ANFs that will exhibit high-characteristic frequencies initially overshoot and sample a large area of targets before refining their connections to correct targets, while fibers that will exhibit low-characteristic frequencies are more accurate in initial targeting and undergo minimal target sampling. Moreover, similar to their peripheral projections, the central projections of ANFs show a gradient of development along the tonotopic axis, with outgrowth and branching of prospective high-frequency ANFs initiated about two days earlier than those of prospective low-frequency ANFs. The processes of synaptogenesis are similar between high- and low-frequency ANFs, but a higher proportion of low-frequency ANFs form smaller endbulb synaptic endings. These observations reveal the diversity of cellular mechanisms that auditory neurons that will become functionally distinct use to innervate their targets during tonotopic map formation.
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影响因子：
16.2
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