Contralateral Inhibition of Click- and Chirp-Evoked Human Compound Action Potentials.
Contralateral Inhibition of Click- and Chirp-Evoked Human Compound Action Potentials.
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DOI：
10.3389/fnins.2017.00189
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发表时间：
2017
影响因子：
4.3
通讯作者：
Cone BK
中科院分区：
文献类型：
--
作者：
Smith SB;Lichtenhan JT;Cone BK
尾侧外毛细胞（OHC）通过内侧橄榄耳蜗（MOC）束接受来自尾侧听觉脑干的直接传出反馈。该电路为MOC反射提供神经基质，MOC反射抑制耳蜗放大器增益，并被认为在噪声中听力和保护免受声学过度刺激中发挥作用。人类MOC反射已被广泛研究，使用耳声发射（OAE）的范例，然而，这些测量是不敏感的后续“下游”传出效应的神经合奏，介导听力。在这个实验中，点击和啁啾诱发的听神经复合动作电位（CAP）的幅度进行了测量，从人的鼓膜没有和MOC反射激活引起的对侧宽带噪声。我们假设，啁啾将是一个更理想的刺激测量神经MOC的影响，因为它沿着沿着整个长度的基底膜的激励，从而唤起一个更强大的CAP比点击在低到中等的刺激水平。在所有刺激强度（50-80 dB ppeSPL）下，啁啾产生的CAP大于滴答声。MOC反射抑制CAPs是更大的啁啾比点击在低刺激水平时，量化的幅度减少和有效衰减。啁啾和点击诱发的CAP的有效衰减大于点击诱发的耳声发射测量从相同的主题。我们的研究结果表明，啁啾是一个最佳的刺激唤起CAP在低刺激强度和评估MOC反射对听神经的影响。此外，我们的工作支持以前的研究结果，MOC反射的影响，在听觉神经的水平被低估的OAE抑制措施。
Cochlear outer hair cells (OHC) receive direct efferent feedback from the caudal auditory brainstem via the medial olivocochlear (MOC) bundle. This circuit provides the neural substrate for the MOC reflex, which inhibits cochlear amplifier gain and is believed to play a role in listening in noise and protection from acoustic overexposure. The human MOC reflex has been studied extensively using otoacoustic emissions (OAE) paradigms; however, these measurements are insensitive to subsequent “downstream” efferent effects on the neural ensembles that mediate hearing. In this experiment, click- and chirp-evoked auditory nerve compound action potential (CAP) amplitudes were measured electrocochleographically from the human eardrum without and with MOC reflex activation elicited by contralateral broadband noise. We hypothesized that the chirp would be a more optimal stimulus for measuring neural MOC effects because it synchronizes excitation along the entire length of the basilar membrane and thus evokes a more robust CAP than a click at low to moderate stimulus levels. Chirps produced larger CAPs than clicks at all stimulus intensities (50–80 dB ppeSPL). MOC reflex inhibition of CAPs was larger for chirps than clicks at low stimulus levels when quantified both in terms of amplitude reduction and effective attenuation. Effective attenuation was larger for chirp- and click-evoked CAPs than for click-evoked OAEs measured from the same subjects. Our results suggest that the chirp is an optimal stimulus for evoking CAPs at low stimulus intensities and for assessing MOC reflex effects on the auditory nerve. Further, our work supports previous findings that MOC reflex effects at the level of the auditory nerve are underestimated by measures of OAE inhibition.