Russell Ian J, Drexl Markus, Foeller Elisabeth, Vater Marianne, Kössl Manfred
School of Life Sciences, University of Sussex, Brighton, BN1 9QG United Kingdom.
J Neurosci. 2003 Oct 22;23(29):9508-18. doi: 10.1523/JNEUROSCI.23-29-09508.2003.
Cochlear microphonic potential (CM) was recorded from the CF2 region and the sparsely innervated zone (the mustached bat's cochlea fovea) that is specialized for analyzing the Doppler-shifted echoes of the first-harmonic (approximately 61 kHz) of the constant-frequency component of the echolocation call. Temporal analysis of the CM, which is tuned sharply to the 61 kHz cochlear resonance, revealed that at the resonance frequency, and within 1 msec of tone onset, CM is broadly tuned with linear magnitude level functions. CM measured during the ongoing tone and in the ringing after tone offset is 50 dB more sensitive, is sharply tuned, has compressive level functions, and the phase leads onset CM by 90 degrees: an indication that cochlear responses are amplified during maximum basilar membrane velocity. For high-level tones above the resonance frequency, CM appears at tone onset and after tone offset. Measurements indicate that the two oscillators responsible for the cochlear resonance, presumably the basilar and tectorial membranes, move together in phase during the ongoing tone, thereby minimizing net shear between them and hair cell excitation. For tones within 2 kHz of the cochlear resonance the frequency of CM measured within 2 msec of tone onset is not that of the stimulus but is proportional to it. For tones just below the cochlear resonance region CM frequency is a constant amount below that of the stimulus depending on CM measurement delay from tone onset. The frequency responses of the CM recorded from the cochlear fovea can be accounted for through synchronization between the nonlinear oscillators responsible for the cochlear resonance and the stimulus tone.
耳蜗微音器电位（CM）是从CF2区域和稀疏神经支配区（髯蝠的耳蜗中央凹）记录的，该区域专门用于分析回声定位叫声的恒定频率成分的一次谐波（约61kHz）的多普勒频移回声。对CM进行时间分析，其对61kHz的耳蜗共振有尖锐调谐，结果显示在共振频率下，且在音调开始后的1毫秒内，CM具有线性幅度水平函数的宽调谐。在持续音调期间和音调偏移后的振铃期间测量的CM灵敏度高50dB，调谐尖锐，具有压缩水平函数，并且相位比起始CM超前90度：这表明在基底膜最大速度期间耳蜗反应被放大。对于高于共振频率的高强度音调，CM出现在音调开始时和音调偏移后。测量表明，负责耳蜗共振的两个振荡器，大概是基底膜和盖膜，在持续音调期间同相移动，从而使它们之间的净剪切力和毛细胞兴奋最小化。对于在耳蜗共振2kHz范围内的音调，在音调开始后2毫秒内测量的CM频率不是刺激频率，而是与刺激频率成比例。对于刚好低于耳蜗共振区域的音调，CM频率比刺激频率低一个恒定值，这取决于从音调开始的CM测量延迟。从耳蜗中央凹记录到的CM的频率响应可以通过负责耳蜗共振的非线性振荡器与刺激音调之间的同步来解释。
