The Auditory Nerve Overlapped Waveform (ANOW) Originates in the Cochlear Apex
The Auditory Nerve Overlapped Waveform (ANOW) Originates in the Cochlear Apex
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DOI：
10.1007/s10162-014-0447-y
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发表时间：
2014-06-01
影响因子：
2.4
通讯作者：
Salt, A. N.
中科院分区：
文献类型：
--
作者：
Lichtenhan, J. T.;Hartsock, J. J.;Salt, A. N.
使用复合动作电位 (CAP)、听觉脑干反应和耳声发射来测量耳蜗功能对于高频声音效果良好，但在低频声音时存在问题。我们最近表明，听觉神经重叠波形 (ANOW) 可以客观地量化低频 (< 1 kHz) 听觉灵敏度，因为低频下的 ANOW 阈值和高频下的 CAP 阈值与单个听觉神经纤维阈值类似。然而，这种有利的关系并不一定意味着 ANOW 源自支配耳蜗顶端低频区域的听觉神经纤维。在本研究中，我们记录了在施用河鲀毒素（TTX）阻断神经功能期间耳蜗对低频（353、500和707 Hz）和高频（2至16 kHz）突发音调的反应。 TTX 采用一种新颖的缓慢给药方法，通过密封在耳蜗尖部的移液管进行注射，从而可以实时测量从尖部到基部的系统神经阻滞。在阈值和对中等水平高频声音的反应受到影响之前，对中等水平低频声音的锁相（ANOW）和起始（CAP）神经放电的幅度被显着抑制。这些结果表明，ANOW 源自支配耳蜗尖部的听觉神经纤维的反应，证实 ANOW 提供了低频听觉神经功能的有效生理测量。
Measurements of cochlear function with compound action potentials (CAPs), auditory brainstem responses, and otoacoustic emissions work well with high-frequency sounds but are problematic at low frequencies. We have recently shown that the auditory nerve overlapped waveform (ANOW) can objectively quantify low-frequency (< 1 kHz) auditory sensitivity, as thresholds for ANOW at low frequencies and for CAP at high frequencies relate similarly to single auditory nerve fiber thresholds. This favorable relationship, however, does not necessarily mean that ANOW originates from auditory nerve fibers innervating low-frequency regions of the cochlear apex. In the present study, we recorded the cochlear response to tone bursts of low frequency (353, 500, and 707 Hz) and high frequency (2 to 16 kHz) during administration of tetrodotoxin (TTX) to block neural function. TTX was injected using a novel method of slow administration from a pipette sealed into the cochlear apex, allowing real-time measurements of systematic neural blocking from apex to base. The amplitude of phase-locked (ANOW) and onset (CAP) neural firing to moderate-level, low-frequency sounds were markedly suppressed before thresholds and responses to moderate-level, high-frequency sounds were affected. These results demonstrate that the ANOW originates from responses of auditory nerve fibers innervating cochlear apex, confirming that ANOW provides a valid physiological measure of low-frequency auditory nerve function.