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[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

Received: 2010-05-31　　Accepted: 2010-08-17

Corresponding author: 唐佳　　E-mail: bobaytang@yahoo.com.cn

Citing This Article：

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).