DEVELOPMENT OF PERIPHERAL AUDITORY NONLINEARITIES

周围听觉非线性的发展

• 批准号: 6201705
• 负责人: Edward J Walsh
• 金额: $ 17.26万
• 依托单位: FATHER FLANAGAN'S BOYS' HOME
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2001-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6201705
• 关键词: afferent nerve; audiometry; auditory discrimination; auditory pathways; auditory threshold; biological signal transduction; brain stem; cats; cochlear microphonic potentials; evoked potentials; growth /development; hearing; histogenesis; hypoxia; immature animal; infant animal; microelectrodes; neurogenesis; neurons; otoacoustic emission; single cell analysis; sound frequency; stimulus /response

Although a great deal is known about the nonlinear characteristics of the peripheral auditory systems of adult vertebrates, very little is known about their development. Results from recent experiments indicate that transduction dynamics are linear during the early stages of mammalian development and that the acquisition of adultlike characteristics occurs rapidly for simple forms of stimulation (i.e., tonal stimuli), coinciding with the final stages of cochlear differentiation. Cochlear nonlinearities, on the other hand, in addition to appearing later in postnatal life, require longer to mature than do more simple response features. We hypothesize that nonlinear response properties of the peripheral auditory system arise near the end of the first postnatal week, and that their mechanism(s) of action is independent of frequency, as indicated by the simultaneous developmental appearance of two-tone suppression above and below the characteristic frequency of auditory nerve fibers spanning the audiometric range. We also hypothesize that two-tone suppression and intermodulation distortion products develop in concert with other cochlear phenomena, like tuning, and propose to use converging methods (i.e., Fourier analysis of individual auditory nerve fiber responses and distortion product otoacoustic emissions) to identify commonalities linking otherwise disparate nonlinear phenomena. Very little is known about the development of level-dependent relationships among cochlear distortion products and we hypothesize that they are complex, reflecting the developmental acquisition of dynamic frequency and level properties of peripheral auditory function in general. Distortion product otoacoustic emissions will be employed to accomplish objectives associated with this aspect of proposed research. We also hypothesize that auditory function is more susceptible to energy-depleting and/or blocking actions early in development and plan to experimentally manipulate energy-dependent cochlear processes at various stages of development, through the agencies of systemic furosemide administration and hypoxia. These agents disrupt active cochlear mechanics, and the purpose of proposed experiments is the identification of age-dependent differences revealed by the actions of these manipulations. Ultimately, the purpose of the proposed research is to extend our understanding of the role of peripheral auditory nonlinearities in cochlear processing in adults and immature mammals, as well as to form a basis for future research targeting clinical issues related to congenital deafness, and the consequences of exposure to environmental hazards during critical developmental periods.

虽然已经了解了很多有关的非线性特征 成人脊椎动物的外围听觉系统，鲜为人知 关于他们的发展。 最近的实验结果表明 在哺乳动物的早期阶段，转导动力学是线性的 发展和成人式特征的获取发生 快速用于简单形式的刺激（即音调刺激），重合 与人工耳蜗分化的最后阶段。 人工耳蜗 另一方面，非线性除了以后出现 产后寿命，需要更长的成熟时间 特征。 我们假设该非线性响应特性 外围听觉系统在出生后周末附近发生， 他们的作用机制与频率无关，因为 两色调的同时发育外观表示 在听觉神经的特征频率上方和下方抑制 跨越听力范围的纤维。 我们还假设这是两色调 抑制和间调节失真产物共同发展 与其他人工耳蜗现象（例如调谐），并建议使用融合 方法（即，单个听觉神经纤维的傅立叶分析 响应和失真产物耳声排放）以识别 与其他不同的非线性现象联系起来的共同点。 非常 关于水平依赖关系的发展知之甚少 在耳蜗失真产品中，我们假设它们是 复杂，反映了动态频率和 一般而言，外围听觉功能的级别属性。 失真 产品耳声排放将用于实现目标 与拟议研究的这一方面相关。 我们也假设 该听觉功能更容易受到消耗和/或 在开发早期阻止行动，并计划实验 在各个阶段操纵能量依赖能量的人工耳蜗过程 开发，通过全身速尿给药机构 和缺氧。 这些试剂破坏了主动的人工耳蜗，以及 拟议实验的目的是鉴定年龄依赖性 这些操纵的行为揭示了差异。 最终， 拟议研究的目的是扩展我们对 外围听觉非线性在人工耳蜗处理中的作用 成人和未成熟的哺乳动物，并为未来构成基础 针对与先天性耳聋有关的临床问题的研究， 关键期间暴露于环境危害的后果 发展时期。