菊头幅出生后下丘听神经元反应特性的演化

实验在出生后1周到6周的幼年和成年鲁氏菊头蝠(Rhinolophusrouxi)上进行。结果发现,出生第1周的动物下丘听神经元对超声刺激反应的最佳频率低,潜伏期长,阈值高。它们的平均值分别为:31.24±14.08千赫,16.56±3.83毫秒和74.24±6.22dB。同时,调谐曲线宽阔,Q10-dB值小,其均值为2.34±0.96。随着周令增长,上述特性逐渐改变。到第6周时,最佳频率的均值发展到70.16±19.16千赫,最佳频率分布峰值也移至75—85千赫的高频段,反应潜伏期均值降至8.12±1.86毫秒,阈值均值降至32.82±26.36dB,已出现相当多具有非常陡削调谐曲线的神精元,Q10-dB值在20以上者占到80％,有的高达100以上,已接近成年动物。

POSTNATAL DEVELOPMENT OF THE AUDITORY RESPONSE PROPERTIES IN INFEROIR COLLICULAR NEURONS OF BAT, PHINOLOPHUS ROUXI

Using electrophysiological technique, We studied the responses of inferior collicular (IC) neurons to acoustic stimulus in the juvenile (Ist to 6th postnatal week) and adult rufous horseshoe bat, Rhinolophus rouxi. The results are the following: (1). During the first postnatal week IC neurons had low best frequencies (BFs), long response latencies and high thresholds(MTs). The mean BEs, respons latency, MTs and Q10-dB value were 31.24 ± 14.08 KHz, 16.56 ± 3.83 ms, 74.24±6.22 dB SPL and 2.34 ±0.96 respectively. (2). During postnatal development, these response properties gradually shifted. The average values of mean BFs, latency, MTs and QlO-dB became 48.22±21.33 KHz, 12.41±3.94 ms, 40.24±24.32 dB SPL and 18.61±14.26 respectively in the 4th postnatal week. (3). In the 6th postnatal week the mean BFs progressively expanded towards to 70.16±19.16 KHz, and the peak of BF distribution have already shifted to high frequency band (75-85), the latency were shortened by an average of 8.12±1.86 ms, the MTs were reduced by an average of 32.83±26.35 dB SPL, and most units have become extremely narrowly tuned with high Q10-dB value (some unit up to 100) which reached the auditory functional range of adult bat's (mean BFs: 76.07±l8.31 KHz, mean latency: 6.83±1.77 ms, mean MTs. 28.63±17.79 dB SPL and mean Q10-dB value: 111.96±103.46).