Topographic organization in the auditory brainstem of juvenile mice is disrupted in congenital deafness
Topographic organization in the auditory brainstem of juvenile mice is disrupted in congenital deafness
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DOI：
10.1113/jphysiol.2005.098780
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发表时间：
2006-03-15
影响因子：
5.5
通讯作者：
Walmsley, B
中科院分区：
文献类型：
--
作者：
Leao, RN;Sun, H;Walmsley, B
听性脑干核团内神经元按声音频率有着有序的分布。以前的免疫标记研究中的内侧核的斜方体（MNTB）表明，可能有梯度的电压门控电流的基础上，这种tonotopic安排。在这里，我们的电生理和免疫标记的结果表明，潜在的tonotopic组织的MNTB是一个组合的低和高阈值钾电流和超极化激活的阳离子电流的中侧梯度。我们的研究结果还表明，MNTB神经元的内在膜特性产生的地形梯度的时间延迟，这可能是相关的声音定位，从MNTB的内侧上级橄榄（MSO）的抑制性输入的时间的重要性之前的演示。最重要的是，我们证明，在先天性耳聋小鼠的MNTB，表现出没有自发的听觉神经活动，神经元特性的正常tonotopic梯度是不存在的。我们的研究结果表明，所观察到的地形梯度的神经元放电特性的MNTB的一个潜在的机制，表明一个内在的神经元机制是负责产生地形梯度的时间延迟，并提供直接的证据表明，这些梯度依赖于自发的听觉神经活动在发展过程中。
There is an orderly topographic arrangement of neurones within auditory brainstem nuclei based on sound frequency. Previous immunolabelling studies in the medial nucleus of the trapezoid body (MNTB) have suggested that there may be gradients of voltage-gated currents underlying this tonotopic arrangement. Here, our electrophysiological and immunolabelling results demonstrate that underlying the tonotopic organization of the MNTB is a combination of medio-lateral gradients of low-and high-threshold potassium currents and hyperpolarization-activated cation currents. Our results also show that the intrinsic membrane properties of MNTB neurones produce a topographic gradient of time delays, which may be relevant to sound localization, following previous demonstrations of the importance of the timing of inhibitory input from the MNTB to the medial superior olive (MSO). Most importantly, we demonstrate that, in the MNTB of congenitally deaf mice, which exhibit no spontaneous auditory nerve activity, the normal tonotopic gradients of neuronal properties are absent. Our results suggest an underlying mechanism for the observed topographic gradient of neuronal firing properties in the MNTB, show that an intrinsic neuronal mechanism is responsible for generating a topographic gradient of time-delays, and provide direct evidence that these gradients rely on spontaneous auditory nerve activity during development.