POSTNATAL DEVELOPMENT OF THE AUDITORY RESPONSE PROPERTIES IN INFEROIR COLLICULAR NEURONS OF BAT, PHINOLOPHUS ROUXI
菊头幅出生后下丘听神经元反应特性的演化

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).