Manley G A, Köppl C, Yates G K
Institut für Zoologie, Technische Universität München, Garching, Germany.
J Acoust Soc Am. 1997 Mar;101(3):1560-73. doi: 10.1121/1.418273.
The spontaneous and pure-tone sound-driven activity of primary auditory units was recorded in the cochlear ganglion of emu chicks aged between post-hatching days 1 and 14. Spontaneous activity tended to increase both with the chick's age and as a function of the unit's characteristic frequency (CF). The CF of 887 units ranged from 0.04 to 4 kHz, the thresholds down to 0 dB SPL. Although the CF range did not change, the thresholds improved with age during the first two weeks after hatching, by up to 18 dB at the highest frequencies. The threshold spread between units of similar CF in single animals was up to 60 dB. Rate-threshold tuning-curve symmetry varied with CF. In low-frequency units, the slope of the low-frequency tuning-curve flank was on average steeper than the high-frequency flank, whereas for high-frequency units, the reverse was true. Units of CF > 0.5 kHz generally showed low-frequency "tails" similar to those seen in mammalian primary auditory fibers. The mean tuning-curve frequency selectivity increased with CF. For units of CF > 0.2 kHz, thresholds were moderately correlated with tuning-curve frequency selectivity. Significant phase locking was observed up to about 4 kHz, the corner frequency of phase locking being at 1.15 kHz.
在孵化后1至14天的鸸鹋雏鸡的耳蜗神经节中记录了初级听觉单元的自发活动和纯音驱动活动。自发活动倾向于随着雏鸡年龄的增长以及作为单元特征频率（CF）的函数而增加。887个单元的CF范围为0.04至4 kHz，阈值低至0 dB SPL。虽然CF范围没有变化，但在孵化后的前两周内，阈值随着年龄的增长而改善，在最高频率下提高了18 dB。单只动物中具有相似CF的单元之间的阈值差异高达60 dB。速率-阈值调谐曲线的对称性随CF而变化。在低频单元中，低频调谐曲线侧翼的斜率平均比高频侧翼更陡，而对于高频单元，情况则相反。CF>0.5 kHz的单元通常表现出类似于哺乳动物初级听觉纤维中所见的低频“尾巴”。平均调谐曲线频率选择性随CF增加。对于CF>0.2 kHz的单元，阈值与调谐曲线频率选择性呈中度相关。在高达约4 kHz的频率下观察到明显的相位锁定，相位锁定的转折频率为1.15 kHz。
