豚鼠耳蜗电位幅度“重振”现象的实验观察

Amplitude recruitment of cochlear potential

用胞内记录方法通过对豚鼠耳蜗第三圈记录白噪声暴露前后外毛细胞（OHC）胞内交流感受器电位，中阶记录胞外交流感受器电位（CM），以及圆窗龛处听神经复合动作电位（CAP）及其各自输入-输出函数曲线（I／O）结果提示，噪声暴露前OHC的交流感受器电位和CM的I／O曲线为一具有饱和状态的典型非线性特点，CAP的I／O则为具有低段“平台”和高段的非线性特点，噪声暴露后，CAP阈移10dB），OHC交流感受器电位、CM的I／O非线性特点减弱，线性化增强，CAP的I／O曲线“平台”基本消失，幅度增长率提高．讨论了此现象发生机理可能是OHC的主动反馈（Activefeedback－AF）受损，除增益减小（即听力下降），其交流感受器电位非线性增长功能线性化，使之决定强度编码的基底膜运动也线性化，导致输入的反应（CAP）也线性化．

Intracellular recordings were made from outer hair cells (OHC) and the cochlear microphonics (CM) were recorded from scala media (SM) in third turn of guinea pig cochlea, the compound action potential (CAP) were recorded at the round window (RW) before and after the animal were exposed to white noise. The results suggest that the nonlinear properties with 'saduration' of Input/output (I/O) function of OHC AC recepter potential and CM were founded;the nonlinear properties with 'Low', 'Platean' and 'high' of CAP also were investigated. After explosion, the threshold shift of CAP has about 10 dB. The I/O of OHC responses and CM were changed in a linearizing (i.e., nonlinearity loss), the 'platean' of I/O CAP disappeared and the growth rate of CAP amplitude were larger than before explosion. The response amplitude recruitment of OHC appears to result from reduction in gain (i.e., hearing loss); It was due to the nonlinear growth function of OHC recepter potentials was changed in linearizing that the basilar membrance motion was changed in linearizing. Since intensity coding in the inner ear dependson an interaction of nonlinear basilar membrane and nerve fibers.So that it must lead to a linearizing of CAP as input responses.