中文摘要：

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（inferior colliculus,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0～15ms;短时恢复型（short,S）,50%IPI为15.1～30ms;长时恢复型（long,L）,50%IPI〉30ms。在2、5和7ms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2msCF声转变为2msFM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7msCF声刺激相比,5＋2msCF-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。

英文摘要：

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular（IC） neurons in constant frequency-frequency modulation（CF-FM） bats were explored in this study.Five leaf-nosed bats,Hipposideros armiger（4 males,1 female,43-50 g body weight）,were used as subjects.The extracellular responses of IC neurons to paired sound stimuli with different duration 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 when neurons reached 50% recovery（50% IPI）,the recovery cycles of these IC neurons were classified into 3 types：fast recovery（F,the 50% 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 more than 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% and 18.2% 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 ms and 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