FREQUENCY SPECTRAL INTEGRATION OF INFERIOR COLLICULAR NEURONS IN THE PROCESSING OF SOUND SIGNAL
下丘神经元声信号处理过程中的频谱整合

With a particular two-tone stimulation paradigm under free field conditions, the frequency spectral integration of inferior collicular (IC) neurons was studied by using a pair of 3 mol/L KCL glass electrodes to simultaneously record. The experiments were conducted on 6 big brown bats (Eptesicus fuscus) tranquilized and anesthetized with Innoval-Vet (Fentanyl 0.08 mg/kg b.w., Droperidol 4 mg/kg b.w.) and Nembutal (50 mg/kg b.w.) and 22 paired IC neurons were obtained. The results are as follows: (1) 81.8% (36/44) paired neurons yielded mutually inhibitory spectral integration while others (18.2%, 8/44) mutually facilitated; (2) The most best frequencies (BFs) of correlated neurons (86.4%, 38/44) with integration were within the range of 20~30 kHz. Although there were nearly half of paired neurons (45.5%, 20/44) whose BFs differences were less than 2 kHz, the spectral integration between those neurons (13.6% 6/44) whose BFs differences were more than 10 kHz also can be observed; (3) The acoustic responses selectivity of IC neurons to frequency and intensity were modulated by frequency spectral integration. Our results add evidence to the notion that for better processing of complex sound signals there are mutual interactions of IC neurons within iso-frequency lamina or between iso-frequency lamminae.