The Coda of the Transient Response in a Sensitive Cochlea: A Computational Modeling Study.
The Coda of the Transient Response in a Sensitive Cochlea: A Computational Modeling Study.
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DOI：
10.1371/journal.pcbi.1005015
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发表时间：
2016-07
影响因子：
4.3
通讯作者：
Grosh K
中科院分区：
文献类型：
--
作者：
Li Y;Grosh K
在敏感的耳蜗中，基底膜对任何种类的瞬态激励（正常声学或人工耳蜗内激励）的响应不仅包括初级脉冲，还包括具有不同幅度但在测量位置的特征频率周围具有相似频谱内容的延迟次级响应的尾波。尾波，有时被称为回声或振铃，已经被描述为局部的短期记忆的形式，其可以影响听觉系统检测诸如语音的声学刺激中的间隙的能力。取决于个体耳蜗，主脉冲和随后的尾波之间的时间间隙的范围从主脉冲的群延迟的一到三倍（主脉冲的群延迟是几百微秒的量级）。尾波在生理上是脆弱的，当耳蜗受到轻微损害时就会消失。多组分敏感响应尚未完全理解。我们使用基于生理学的数学模型来研究（i）初级脉冲响应的产生和群延迟对各种刺激方法的依赖性，（ii）机械敏感离子通道特性中的空间扰动对延迟次级响应的产生和分离的影响。该模型表明，次级反应的存在取决于扰动的波数内容和耳蜗的活动水平。此外，该模型表明，在实验中看到的相邻尾波之间的不同的时间间隙取决于个人的扰动配置文件。非侵入性耳蜗诊断的影响进行了讨论。耳蜗中的流体-结构-电相互作用使得耳蜗分区中最重要的结构之一的基底膜能够根据传入声音的频率内容显示不同的动态模式。有趣的是，在健康的耳蜗中，基底膜的运动在传递到耳道的脉冲声刺激时显示回声。这些回声的延迟、持续时间和形状因耳蜗而异。耳蜗分区的属性的不规则性相干地散射声波和产生回声的假设进行检查。这些不规则性被假定为引起例如感觉细胞的损伤或耳蜗分区形态的自然随机性。在这里，我们建立了一个基于生理学的数学模型，通过将不规则性引入感觉细胞的特性来理解实验中观察到的回声。我们发现，回声的模式取决于个人的不规则性。我们的工作表明，耳道记录，这是相关的动力学的基底膜，可以被用作一种非侵入性的工具，不仅诊断颅内损伤，但也解释这些数据鉴于其特异质的起源。
In a sensitive cochlea, the basilar membrane response to transient excitation of any kind–normal acoustic or artificial intracochlear excitation–consists of not only a primary impulse but also a coda of delayed secondary responses with varying amplitudes but similar spectral content around the characteristic frequency of the measurement location. The coda, sometimes referred to as echoes or ringing, has been described as a form of local, short term memory which may influence the ability of the auditory system to detect gaps in an acoustic stimulus such as speech. Depending on the individual cochlea, the temporal gap between the primary impulse and the following coda ranges from once to thrice the group delay of the primary impulse (the group delay of the primary impulse is on the order of a few hundred microseconds). The coda is physiologically vulnerable, disappearing when the cochlea is compromised even slightly. The multicomponent sensitive response is not yet completely understood. We use a physiologically-based, mathematical model to investigate (i) the generation of the primary impulse response and the dependence of the group delay on the various stimulation methods, (ii) the effect of spatial perturbations in the properties of mechanically sensitive ion channels on the generation and separation of delayed secondary responses. The model suggests that the presence of the secondary responses depends on the wavenumber content of a perturbation and the activity level of the cochlea. In addition, the model shows that the varying temporal gaps between adjacent coda seen in experiments depend on the individual profiles of perturbations. Implications for non-invasive cochlear diagnosis are also discussed. The fluid-structure-electrical interaction in the cochlea enable the basilar membrane, one of the most important structures in the cochlear partition, to display different dynamic patterns depending on the frequency content of the incoming sound. Interestingly, in a healthy cochlea the motion of the basilar membrane shows echoes upon an impulse acoustic stimulation delivered to the ear canal. The delay, duration, and shape of these echoes vary from one cochlea to another. A hypothesis that irregularities of the properties of the cochlear partition coherently scatter acoustic waves and generate echoes is examined. These irregularities are posited to arise, for example, the damage of the sensory cells or the natural randomness in the morphology of the cochlear partition. Here we build a physiologically-based mathematical model to understand the echoes observed in experiments by introducing irregularity to the properties of the sensory cells. We found that the patterns of the echoes depend on the individual profiles of the irregularities. Our work suggest that the ear canal recording, which is correlated to the dynamics of the basilar membrane, can be used as a non-invasive tool not only to diagnose the intracochlear damage but also to interpret these data given its idiosyncratic origin.