动物造模 z-bio 2021-12-06 741

　　Objective To observe the changes in auditory sensitivity and time resolution and the time correlation between the two during the development of the rat auditory system using the pre-reflex suppression method of auditory startle reflex.

　　Methods Twenty newborn SD rats with a daily age of 14.16.18.22.26.30.35 days were selected. The rats were divided into 2 groups with 10 rats in each group. The rats in each day-old group were subjected to auditory brain Dry response (ABR) test and pre-acoustic startle reflex inhibition test. One group of rats has a marked background noise frequency of 1-48 kHz during the test, and the other group of rats has a background noise frequency of 8-32 kHz.

　　Results 1.2 and 4 kHz ABB thresholds on the 26th day, 16 and 32 kHz ABR thresholds on the 22nd day, 8 and 48 kHz ABR thresholds on the 18th day and the 35th day were not statistically different (P>0.05) Therefore, on the 26th day after birth, the various frequencies of the rat’s auditory system have been fully developed, and the hearing acuity has reached the level of normal adult rats. The pre-startle reflex inhibition test shows that when the background noise is 8-32 kHz, the 14th The interval threshold for rats on day 30 is about 50 ms; the threshold for rats on day 16.18.22.26 is 25 ms; the threshold for rats on day 30 is 15 ms; the threshold for rats on day 35 is 8 ms. When the background noise is 1-48 kHz, the interval threshold is significantly decreased (P=0. 013), the interval threshold of the rat on the 14th day is 25 ms; the interval threshold of the rat on the 16.18 day is 15 ms; the 22.26.30.35 The interval threshold of the day rat was 10 ms, but under the two kinds of background noise, the time resolution both matured on the 30th day.

　　Conclusion During the development of the rat auditory system, the development of temporal resolution lags behind the development of auditory acuity.