Envelope Coding in Auditory Nerve Fibers Following Noise-Induced Hearing Loss
Envelope Coding in Auditory Nerve Fibers Following Noise-Induced Hearing Loss
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DOI：
10.1007/s10162-010-0223-6
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发表时间：
2010-12-01
影响因子：
2.4
通讯作者：
Heinz, Michael G.
中科院分区：
文献类型：
--
作者：
Kale, Sushrut;Heinz, Michael G.
最近的感知研究表明，与感音神经性听力损失（SNHL）的听众有一个降低的能力，使用时间的精细结构线索，而SNHL对时间包络线索的影响通常被认为是最小的。几项感知研究表明，SNHL之后的包络编码实际上可能会得到增强，并且这种效果实际上可能会降低调制掩蔽中的收听（例如，竞争的谈话者）。本研究探讨了SNHL对听觉神经（AN）纤维中与精细结构编码相关的包络编码的生理效应。反应进行了比较与正常的听力和那些有轻度中度噪声引起的听力损失的麻醉龙猫。时间包络编码的窄带调制的刺激（正弦振幅调制的音调和单一共振峰刺激）进行了量化与几个神经指标。信封和精细结构编码的相对强度进行了比较，使用洗牌相关分析。平均而言，暴露于噪音的AN纤维的包络编码强度增强。在AN纤维中观察到高度增强的信封编码，具有高阈值和非常陡峭的速率水平功能，这可能与严重的外毛细胞和内毛细胞损伤有关。细结构编码的退化被观察到的AN纤维编码主要是细结构或信封之间的过渡发生在较低的特征频率以下SNHL。尽管AN纤维编码精细结构的基本能力没有退化，但这种相对精细结构的退化发生，并且不依赖于降低的频率选择性。总体而言，这些数据表明，需要考虑SNHL的相对影响的信封和精细结构编码在评估复杂的刺激的时间处理的知觉缺陷。
Recent perceptual studies suggest that listeners with sensorineural hearing loss (SNHL) have a reduced ability to use temporal fine-structure cues, whereas the effects of SNHL on temporal envelope cues are generally thought to be minimal. Several perceptual studies suggest that envelope coding may actually be enhanced following SNHL and that this effect may actually degrade listening in modulated maskers (e.g., competing talkers). The present study examined physiological effects of SNHL on envelope coding in auditory nerve (AN) fibers in relation to fine-structure coding. Responses were compared between anesthetized chinchillas with normal hearing and those with a mild-moderate noise-induced hearing loss. Temporal envelope coding of narrowband-modulated stimuli (sinusoidally amplitude-modulated tones and single-formant stimuli) was quantified with several neural metrics. The relative strength of envelope and fine-structure coding was compared using shuffled correlogram analyses. On average, the strength of envelope coding was enhanced in noise-exposed AN fibers. A high degree of enhanced envelope coding was observed in AN fibers with high thresholds and very steep rate-level functions, which were likely associated with severe outer and inner hair cell damage. Degradation in fine-structure coding was observed in that the transition between AN fibers coding primarily fine structure or envelope occurred at lower characteristic frequencies following SNHL. This relative fine-structure degradation occurred despite no degradation in the fundamental ability of AN fibers to encode fine structure and did not depend on reduced frequency selectivity. Overall, these data suggest the need to consider the relative effects of SNHL on envelope and fine-structure coding in evaluating perceptual deficits in temporal processing of complex stimuli.