Mechanisms of the phase locking of auditory-nerve fibers: a modeling approach

听觉神经纤维锁相机制：建模方法

• 批准号: 217863086
• 负责人: Professor Dr. Peter Heil
• 金额: --
• 依托单位: Abteilung Systemphysiologie des Lernens
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2012
• 资助国家: 德国
• 起止时间: 2011-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/217863086?language=en
• 关键词: Mechanisms; phase; locking; auditory; nerve

A hallmark of the extraordinary temporal precision of the auditory system and its processing speed is phase locking of neuronal discharges (spikes) of auditory-nerve fibers (ANFs; the primary afferents), and some more central neurons, to the fine-structure of acoustic stimuli. In response to tones, for example, phase locking is reflected in a peaked distribution of spikes over a stimulus cycle, even those that are 200 µs or shorter (the limit depending on species), with a temporal dispersion as low as 30 µs. Phase locking by ANFs appears crucial for sound localization and the perception of pitch, a salient feature of music, speech, and other vocalizations, and has also been used as a tool to infer cochlear mechanics. To this end, we developed a parsimonious phenomenological model that accurately accounts for the instantaneous spike probability of cat ANFs in the course of a stimulus cycle, as functions of sound frequency and level. A key requirement of this model is a dynamic Boltzmann transfer function at the front end, which rapidly adapts to the prevailing sound level. We also developed a model of synaptic-vesicle-pool depletion and replenishment that accurately accounts for spiking statistics (interspike interval distributions, serial interval correlations, and spike-count distributions) of these ANFs during spontaneous activity. We now plan to combine the two models to also account for the spiking statistics of sound-driven phase-locked responses. We also plan to further characterize the dynamics of the Boltzmann transfer function by recording ANF responses to novel mixed-amplitude stimuli and examining phase locking on a cycle-by-cycle basis. Furthermore, we plan to test the more general validity of our models by applying them to data from birds and from Bassoon mutant mice with altered ribbon synapses. Our work will help identify the key mechanisms underlying the remarkable temporal precision of ANF responses.

听觉系统的时间精确性及其处理速度的一个标志是听觉神经纤维（ANF;初级传入）和一些更多的中枢神经元的神经元放电（尖峰）与声学刺激的精细结构的相位锁定。例如，在对音调的响应中，锁相反映在刺激周期内尖峰的峰值分布中，即使是200 µs或更短的尖峰（限制取决于物种），时间分散低至30 µs。ANF的相位锁定对于声音定位和音高感知（音乐、语音和其他发声的显著特征）显得至关重要，并且也被用作推断耳蜗力学的工具。为此，我们开发了一个简约的现象学模型，准确地占在刺激周期的过程中的猫ANFs的瞬时尖峰概率，作为声音频率和水平的函数。该模型的一个关键要求是前端的动态玻尔兹曼传递函数，它可以快速适应当前的声级。我们还开发了一个模型的突触囊泡池耗尽和补充，准确地占尖峰统计（interspike间隔分布，串行间隔的相关性，和尖峰计数分布），这些ANFs在自发活动。我们现在计划将这两个模型联合收割机结合起来，以解释声音驱动锁相响应的尖峰统计。我们还计划通过记录ANF对新的混合振幅刺激的反应并在逐周期的基础上检查锁相来进一步表征玻尔兹曼传递函数的动态。此外，我们计划通过将其应用于鸟类和具有改变的带状突触的巴松管突变小鼠的数据来测试我们的模型的更普遍的有效性。我们的工作将有助于确定关键机制的显着时间精度ANF反应。