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小鼠下丘神经元的调制率选择性及其影响因素

廖阳, 臧旭东, 韩小燕, 李安安, 陈其才, 吴飞健

华中师范大学生命科学学院，基因调控与整合生物学湖北省重点实验室，武汉 430079； 湖北第二师范学院化学与生命科学系，武汉 430205

摘要

调频 (frequency modulated, FM)声广泛存在于动物通讯声及人类语言声信号中，虽然已在多种动物的不同听结构中发现有些神经元具有调制率选择性，但其影响因素及形成机制并不明了。本研究在自由声场条件下，采用在体细胞外单位记录方法，探讨昆明小鼠下丘神经元的调制率选择性及其影响因素。实验共在102 个神经元上获得了完整数据。在纯音刺激条件下，41.2% 的神经元(42/102)具有时程调谐特征，其中22.6% (23/102)为短通型，8.8% (9/102)为带通型，9.8%(10/102)为长通型。非时程调谐神经元占58.8% (60/102)。改用FM 声刺激后，大多数时程调谐神经元(78.6%, 33/42)显示出与时程选择相关的调制率选择性，但在不同带宽下具有不同的最佳调制率，其调制率选择性类型完全受时程调谐特性主导，和FM 声带宽无关。部分时程调谐神经元表现出和时程不相关的调制率选择类型(11.9%, 5/42)，或者丧失时程(或者调制率)选择性(9.5%, 4/42)。此外，超过一半的(53.3%, 32/60)非时程调谐神经元在FM 声下出现调制率选择性，且几乎全部为快调制率选择类型(96.9%, 31/32)。该类神经元中，部分神经元(25.0%, 8/32)在不同FM 声带宽下保持相同的最佳调制率，表现出真正的调制率选择性。以上结果表明，小鼠下丘神经元的时程调谐特性在定型其调制率选择性类型方面起关键作用，部分神经元的调制率选择性则取决于FM 声的带宽，而真正意义上的调制率选择性神经元在小鼠下丘并不多见。

关键词： 调制率选择; 调制范围; 时程; 下丘; 小鼠

分类号：Q437

[Selectivity for the rate of frequency-modulated sweeps and its affecting factors in the inferior collicular neurons of mouse.] [Ariticle in Chinese]

LIAO Yang, ZANG Xu-Dong, HAN Xiao-Yan, LI An-An, CHEN Qi-Cai, WU Fei-Jian

College of Life Sciences and Hubei Key Lab of Genetic Regulation and Integrative Biology, Central China Normal University, Wuhan 430079, China； Department of Life Sciences and Chemistry, Hubei University of Education, Wuhan 430205, China

Abstract

Both animal communication sounds and human speech contain frequency-modulated (FM) sweeps. Although the selectivity for the rate of FM sweeps in neurons has been found in many kinds of animals at different levels of the central auditory structures, the underlying neural mechanism is still not clear. Using extracellular single unit recording techniques, we examined the selectivity for the rate of FM sweeps in the inferior colliculus (IC) neurons of the Kunming mouse (Mus musculus, Km) in the free-field stimulation conditions and determined its affecting factors. Totally, 102 neurons were recorded successfully, among which 42 neurons (41.2%) displayed a duration tuning pattern under pure tone (PT) stimulus. The percentages of short-pass, band-pass, and long-pass neurons were 22.6% (23/10), 8.8% (9/102), 9.8% (10/102), respectively. The other 60 neurons (58.8%) did not show any duration tuning features. Under FM stimulus, the majority of duration tuning neurons (78.6%, 33/42) showed the selectivity for the rate of FM sweeps. For these neurons, the type of rate selectivity was determined by the duration tuning features, but it was not related to the modulation range (MR) of FM. In a small fraction of duration tuning neurons (21.4%, 9/42), the rate selectivity was correlated with the MR, but uncorrelated with the duration tuning features. On the other hand, more than half of the non-duration tuning neurons (53.3%, 32/60) exhibited the rate selectivity under FM stimulus, and almost all of them (31/32) showed fast-rate selectivity. Nevertheless, there were 8 neurons (in 32) displaying the same best rate at different MR, indicating that they were real rate-selective neurons. Our results indicate that the selectivity for the rate of FM sweeps is co-determined by duration tuning features and sweep bandwidth. Only a few of inferior colliculus neurons belong to real rate-selectivity neurons in the mouse.

Key words: rate of frequency-modulated sweeps; modulation range; duration tuning; inferior colliculus; mouse.

收稿日期：2009-05-05　　录用日期：2009-07-22

通讯作者：吴飞健　　E-mail: wufj@main.ccun.edu.cn

引用本文：

廖阳, 臧旭东, 韩小燕, 李安安, 陈其才, 吴飞健. 小鼠下丘神经元的调制率选择性及其影响因素[J]. 生理学报 2009; 61 (5): 469-479.

LIAO Yang, ZANG Xu-Dong, HAN Xiao-Yan, LI An-An, CHEN Qi-Cai, WU Fei-Jian. [Selectivity for the rate of frequency-modulated sweeps and its affecting factors in the inferior collicular neurons of mouse.] [Ariticle in Chinese] . Acta Physiol Sin 2009; 61 (5): 469-479 (in Chinese with English abstract).