Distorted Tonotopic Coding of Temporal Envelope and Fine Structure with Noise-Induced Hearing Loss
Distorted Tonotopic Coding of Temporal Envelope and Fine Structure with Noise-Induced Hearing Loss
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DOI：
10.1523/jneurosci.3944-15.2016
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发表时间：
2016-02-17
影响因子：
5.3
通讯作者：
Heinz, Michael G.
中科院分区：
文献类型：
--
作者：
Henry, Kenneth S.;Kale, Sushrut;Heinz, Michael G.
具有耳蜗听力损失的人在真实世界的收听环境中理解语音具有相当大的困难（例如，即使有现代数字助听器的放大。不幸的是，人类感知研究之间仍然存在脱节，这意味着对快速声学时间精细结构（TFS）的敏感性降低，而动物研究显示TFS或较慢包络（ENV）结构的神经编码变化极小。在这里，我们使用一般的系统识别（维纳内核）分析的灰鼠听觉神经纤维的反应，高斯噪声，揭示显着的失真的音调编码的TFS和ENV以下永久性的，噪声引起的听力损失。在特征频率（CF）>1.5 kHz的基底纤维中，听力损失引入了鲁棒的非音调定位编码（即，在错误的耳蜗位置）的低频TFS，而ENV反应通常保持在CF。因此，TFS编码响应于高斯噪声的最高主频为2.4 kHz，在噪声过度暴露的纤维与4.5 kHz的控制纤维相比。在更明显的耳蜗损伤病例中，ENV编码也变得非音调性。在顶端纤维中，观察到更经典的听力损失效应，即，在最佳频率没有显著偏移的情况下加宽调谐。由于TFS/ENV的这些失真和解离破坏了音调性，这是在背景噪声中进行鲁棒信号编码所必需的听觉处理的基本原则，因此这些结果对于理解听力损失患者所面临的沟通困难具有重要意义。此外，助听器可以受益于针对顶端和基底耳蜗区域的不同放大策略，以解决根本不同的编码缺陷。
People with cochlear hearing loss have substantial difficulty understanding speech in real-world listening environments (e.g., restaurants), even with amplification from a modern digital hearing aid. Unfortunately, a disconnect remains between human perceptual studies implicating diminished sensitivity to fast acoustic temporal fine structure (TFS) and animal studies showing minimal changes in neural coding of TFS or slower envelope (ENV) structure. Here, we used general system-identification (Wiener kernel) analyses of chinchilla auditory nerve fiber responses to Gaussian noise to reveal pronounced distortions in tonotopic coding of TFS and ENV following permanent, noise-induced hearing loss. In basal fibers with characteristic frequencies (CFs) >1.5 kHz, hearing loss introduced robust nontonotopic coding (i.e., at the wrong cochlear place) of low-frequency TFS, while ENV responses typically remained at CF. As a consequence, the highest dominant frequency of TFS coding in response to Gaussian noise was 2.4 kHz in noise-overexposed fibers compared with 4.5 kHz in control fibers. Coding of ENV also became nontonotopic in more pronounced cases of cochlear damage. In apical fibers, more classical hearing-loss effects were observed, i.e., broadened tuning without a significant shift in best frequency. Because these distortions and dissociations of TFS/ENV disrupt tonotopicity, a fundamental principle of auditory processing necessary for robust signal coding in background noise, these results have important implications for understanding communication difficulties faced by people with hearing loss. Further, hearing aids may benefit from distinct amplification strategies for apical and basal cochlear regions to address fundamentally different coding deficits.