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声刺激时程和模式影响大蹄蝠下丘神经元的恢复周期

唐佳^*, 付子英, 吴飞健

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

摘要

本文旨在探讨声刺激时程及模式参量对恒频- 调频(constant frequency-frequency modulation, CF-FM)蝙蝠下丘(inferiorcolliculus, IC)神经元恢复周期的影响。实验选用5 只听力正常的大蹄蝠为实验动物，采用不同时程或不同模式的双声刺激，记录IC 神经元的反应和恢复周期。结果共记录到169 个IC 声敏感神经元。依据神经元恢复率达到50% 时的双声刺激间隔(interpulse interval, IPI)将神经元恢复周期分为三种类型：快速恢复型(fast, F)，50% IPI 为0 ~ 15 ms；短时恢复型(short, S)，50% IPI 为15.1 ~ 30 ms；长时恢复型(long, L)，50% IPI > 30 ms。在2、5 和7 ms 时程的CF 声刺激下，神经元50% IPI 平均值随声刺激时程的增加，分别为(30.2 ± 27.6)、(39.9 ± 29.1)和(49.4 ± 34.7) ms，F 和S 型神经元比例逐渐下降，而L 型神经元比例逐渐上升。当声刺激模式由2 ms CF声转变为2 ms FM声时， F、S 和L 三种类型神经元比例分别由32.3%、41.5%、26.2% 转变为47.7%、24.6%、27.7%，平均恢复周期缩短，由(30.2 ± 27.6)减至(23.9 ± 19.0) ms (P < 0.05, n = 65)。与7 msCF 声刺激相比，5+2 ms CF-FM声刺激使F 型神经元比例上升(18.2% → 29.1%)，S 型神经元(29.1% → 27.3%)和L 型神经元(52.7% → 43.6%)比例下降，平均恢复周期缩短，由(49.4 ± 34.7)减至(36.3 ± 29.4) ms (P < 0.05, n = 55)。结果提示，CF-FM蝙蝠回声定位信号中的CF 和FM 成分在蝙蝠导航和捕食过程中分别扮演不同的角色，其中终末相中的FM 成分主要使F 型神经元数量增多，平均恢复周期缩短。FM 成分在蝙蝠靠近靶物的过程中发挥重要作用以快速处理高脉冲重复率回声信息，它有利于准确计算目标距离和识别目标表面质地。

关键词： 声刺激时程; 声模式; 恢复周期; 恒频-调频蝙蝠

分类号：Q437

[Sound duration and sound pattern affect the recovery cycles of inferior collicular neurons in leaf-nosed bat, Hipposideros armiger.] [Ariticle in Chinese]

Tang Jia^*, FU Zi-Ying, WU Fei-Jian

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

Abstract

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular (IC) neurons in constantfrequency-frequency modulation (CF-FM) bats were explored in this study. Five leaf-nosed bats, Hipposideros armiger (4 males, 1female, 43-50 g body weight), were used as subjects. The extracellular responses of IC neurons to paired sound stimuli with differentduration and patterns were recorded, and the recovery was counted as the ratio of the second response to the first response. Totally,169 sound-sensitive IC neurons were recorded in the experiment. According to the interpulse interval (IPI) of paired sounds whenneurons reached 50% recovery (50% IPI), the recovery cycles of these IC neurons were classified into 3 types: fast recovery (F, the50% IPI was less than 15 ms), short recovery (S, the 50% IPI was between 15.1 and 30 ms) and long recovery (L, the 50% IPI was morethan 30 ms). When paired CF stimuli with 2 ms duration was used, the ratio of F neurons was 32.3%, and it decreased to 18.1% and18.2% respectively when 5 and 7 ms CF stimuli were used. The ratios of S and L neurons were 41.5%, 33.7%, 29.1% and 26.2%, 48.2%,52.7% respectively when 2, 5 and 7 ms CF stimuli were used. The average 50% IPI determined after stimulation with paired 2 ms, 5 msand 7 ms CF sounds were (30.2 ± 27.6), (39.9 ± 29.1) and (49.4 ± 34.7) ms, respectively, and the difference among them was significant(P < 0.01). When the stimuli of paired 2 ms CF sounds were shifted to paired 2 ms FM sounds, the proportion of F, S and L neurons changed from 32.3%, 41.5%, 26.2% to 47.7%, 24.6%, 27.7%, respectively, and the average 50% IPI decreased from (30.2 ± 27.6) to(23.9 ± 19.0) ms (P < 0.05, n = 65). When paired 5+2 ms CF-FM pulses were used instead of 7 ms CF sounds, the proportion of F,S and L neurons changed from 18.2%, 29.1%, 52.7% to 29.1%, 27.3%, 43.6%, respectively, and the average 50% IPI decreased from(49.4 ± 34.7) to (36.3 ± 29.4) ms (P < 0.05, n = 55). All these results suggest that the CF and FM components in echolocation signalof CF-FM bats play different roles during bats’ hunting and preying on. The FM component of CF-FM signal presenting in theterminal phase can increase the number of F type neurons and decrease the recovery cycles of IC neurons for processing high repetitionecho information, which ensures the bat to analyze the target range and surface texture more accurately.

Key words: sound duration; sound pattern; recovery cycle; CF-FM bat

收稿日期：2010-05-31　　录用日期：2010-08-17

通讯作者：唐佳　　E-mail: bobaytang@yahoo.com.cn

引用本文：

唐佳, 付子英, 吴飞健. 声刺激时程和模式影响大蹄蝠下丘神经元的恢复周期[J]. 生理学报 2010; 62 (5): 469-477.

Tang Jia, FU Zi-Ying, WU Fei-Jian. [Sound duration and sound pattern affect the recovery cycles of inferior collicular neurons in leaf-nosed bat, Hipposideros armiger.] [Ariticle in Chinese] . Acta Physiol Sin 2010; 62 (5): 469-477 (in Chinese with English abstract).