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[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.

Received: 2009-05-05　　Accepted: 2009-07-22

Corresponding author: 吴飞健　　E-mail: wufj@main.ccun.edu.cn

Citing This Article：

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).