Modeling temporal information encoding by the population of fibers in the healthy and synaptopathic auditory nerve
Modeling temporal information encoding by the population of fibers in the healthy and synaptopathic auditory nerve
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DOI：
10.1016/j.heares.2022.108621
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发表时间：
2022-09-28
期刊：
影响因子：
2.8
通讯作者：
Lopez-Poveda, Enrique A.
中科院分区：
文献类型：
--
作者：
Johannesen, Peter T.;Leclere, Thibaud;Lopez-Poveda, Enrique A.
我们报告了一项理论研究，旨在探讨耳蜗突触丧失（突触病）对听神经纤维群体对声音包膜（ENV）和时间精细结构（TFS）编码的影响。采用计算模型模拟了不同载波频率和电平的10 Hz正弦波调幅（AM）音调诱发的听神经尖峰序列。该模型包括16个耳蜗通道，特征频率为250 Hz至8 kHz。每个通道分别由低自发率（LSR）、中自发率（MSR）和高自发率（HSR）的3、4和10条纤维支配。对于每个通道，尖峰序列被分解成三个独立的“种群”刺激后时间直方图（pths），每个纤维类型一个。应用信息论以数学上最优的方式从一个或多个pshs重构刺激波形、ENV和TFS。重建的质量被认为是对使用的ppss中存在的信息的估计。在刺激重建之前，通过去除特定类型和/或耳蜗区域的纤维来模拟各种突触病变情景。我们发现，在所有刺激载波频率和水平下，TFS主要由高铁纤维编码。ENV的编码比较复杂。在较低水平下，ENV主要由靠近刺激载波频率的CFs的HSR纤维编码。在更高的水平上，具有不同于AM载波频率的cf的高铁光纤与具有载波频率cf的LSR光纤对ENV的编码同样好或更好。总之，研究结果表明，健康的高铁纤维（即，包括在AM载波频率附近和远离CFs的纤维）可能足以在广泛的刺激水平范围内编码ENV和TFS。研究结果讨论了使用无创env和基于tfs的测量方法诊断突触病变的相关性。(c) 2022作者。这是一篇基于CC by-nc-nd许可的开放获取文章（http://creativecommons.org/licenses/by-nc-nd/4.0/）
We report a theoretical study aimed at investigating the impact of cochlear synapse loss (synaptopathy) on the encoding of the envelope (ENV) and temporal fine structure (TFS) of sounds by the population of auditory nerve fibers. A computational model was used to simulate auditory-nerve spike trains evoked by sinusoidally amplitude-modulated (AM) tones at 10 Hz with various carrier frequencies and levels. The model included 16 cochlear channels with characteristic frequencies (CFs) from 250 Hz to 8 kHz. Each channel was innervated by 3, 4 and 10 fibers with low (LSR), medium (MSR), and high spontaneous rates (HSR), respectively. For each channel, spike trains were collapsed into three separate 'population' post-stimulus time histograms (PSTHs), one per fiber type. Information theory was applied to reconstruct the stimulus waveform, ENV, and TFS from one or more PSTHs in a mathematically optimal way. The quality of the reconstruction was regarded as an estimate of the information present in the used PSTHs. Various synaptopathy scenarios were simulated by removing fibers of specific types and/or cochlear re-gions before stimulus reconstruction. We found that the TFS was predominantly encoded by HSR fibers at all stimulus carrier frequencies and levels. The encoding of the ENV was more complex. At lower levels, the ENV was predominantly encoded by HSR fibers with CFs near the stimulus carrier frequency. At higher levels, the ENV was equally well or better encoded by HSR fibers with CFs different from the AM carrier frequency as by LSR fibers with CFs at the carrier frequency. Altogether, findings suggest that a healthy population of HSR fibers (i.e., including fibers with CFs around and remote from the AM carrier frequency) might be sufficient to encode the ENV and TFS over a wide range of stimulus levels. Find-ings are discussed regarding their relevance for diagnosing synaptopathy using non-invasive ENV-and TFS-based measures. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )