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小鼠外侧丘系背核神经元对纯音的反应特性

佀文娟, 程艳玲, 杨丹丹, 王欣^*

华中师范大学生命科学学院，湖北省遗传调控与整合生物学重点实验室，武汉 430079

摘要

外侧丘系背核(dorsal nuclei of lateral lemniscus, DNLL)是听觉信息上传通路中的神经核团，是下丘抑制性输入的重要来源。目前对DNLL的研究远不如对听觉低位脑干和中脑下丘那么广泛而深入，对于小鼠这种常用听觉模式动物的DNLL的研究尚未见报道。本实验在自由声场条件下，采用单单位细胞外记录的方法，研究了昆明小鼠(Mus musculus, Km) DNLL神经元对纯音的声反应特性。实验结果显示，小鼠DNLL神经元对纯音刺激的发放模式分为瞬时型(36%)与长时型(64%)两类，两类发放模式对应的特征频率和阈值存在显著性差异。DNLL神经元的频率调谐曲线(frequency tuning curves, FTCs)均为开放的“V”型，瞬时型与长时型神经元的FTC无显著差异，但长时型神经元中持续型神经元的FTC明显较起始-持续型和暂停型神经元更为锐化。与猫等动物不同，小鼠DNLL神经元的特征频率与深度之间无线性相关(P > 0.05)，未见背腹轴音频拓扑组构。DNLL神经元的放电率-强度函数(rate-intensity function, RIF)分为单调型(60%)、饱和型(31%)和非单调型 (8%)。三种RIF均包含瞬时型与长时型发放模式，瞬时型神经元对应的动态范围显著小于长时型(P < 0.01)，这可能与瞬时型神经元接受较多的抑制性输入有关。小鼠DNLL神经元存在多样的发放模式和声强编码方式，源于其接受多个听觉核团的投射，其在听觉信息的处理过程中发挥不同的作用。

关键词： 外侧丘系背核; 发放模式 ; 频率调谐 ; 强度调谐 ; 小鼠

分类号：Q6;R338

Response characteristics of neurons to tone in dorsal nucleus of the lateral lemniscus of the mouse

SI Wen-Juan, CHENG Yan-Ling, YANG Dan-Dan, WANG Xin^*

College of Life Sciences and Hubei Key Laboratory of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China

Abstract

The dorsal nucleus of lateral lemniscus (DNLL) is a nucleus in the auditory ascending pathway, and casts inhibitory efferent projections to the inferior colliculus. Studies on the DNLL are less than studies on the auditory brain stem and inferior colliculus. To date, there is no information about response characteristics of neurons in DNLL of albino mouse. Under free field conditions, we used extracellular single unit recording to study the acoustic signal characteristics of DNLL neurons in Kunming mice (Mus musculus). Transient (36%) and ongoing (64%) firing patterns were found in 96 DNLL neurons. Neurons with different firing patterns have significant differences in characteristic frequency and minimal threshold. We recorded frequency tuning curves (FTCs) of 87 DNLL neurons. All of the FTCs exhibit an open “V” shape. There is no significant difference in FTCs between transient and ongoing neurons, but among the ongoing neurons, the FTCs of sustained neurons are sharper than those of onset plus sustained neurons and pauser neurons. Our results showed that the characteristic frequency of DNLL neurons of mice was not correlated with depth, supporting the view that the DNLL of mouse has no frequency topological organization through dorsal-ventral plane, which is different from cats and some other animals. Furthermore, by using rate-intensity function (RIF) analysis the mouse DNLL neurons can be classified as monotonic (60%), saturated (31%) and non-monotonic (8%) types. Each RIF type includes transient and ongoing firing patterns. Dynamic range of the transient firing pattern is smaller than that of ongoing firing ones (P < 0.01), suggesting that the inhibitory inputs may underlie the formation of transient firing pattern. Multiple firing patterns and intensity coding of DNLL neurons may derive from the projections from multiple auditory nuclei, and play different roles in auditory information processing.

Key words: dorsal nuclei of lateral lemniscus; firing pattern ; frequency tuning ; intensity tuning ; mouse

收稿日期：2015-07-08　　录用日期：2015-12-21

通讯作者：王欣　　E-mail: xueyue312@aliyun.com

引用本文：

佀文娟, 程艳玲, 杨丹丹, 王欣. 小鼠外侧丘系背核神经元对纯音的反应特性[J]. 生理学报 2016; 68 (1): 1-11.

SI Wen-Juan, CHENG Yan-Ling, YANG Dan-Dan, WANG Xin. Response characteristics of neurons to tone in dorsal nucleus of the lateral lemniscus of the mouse. Acta Physiol Sin 2016; 68 (1): 1-11 (in Chinese with English abstract).