Bilateral cochlear implants:Physiology and psychophysics

描述(由申请人提供)：双耳听力对于准确的声音定位和在相互竞争的声源中听出感兴趣的声音是必不可少的，而这些双耳优势是双耳人工耳蜗术数量增加的重要激励因素。在这项应用中，来自麻省理工学院眼耳医院、麻省理工学院和波士顿大学的三个实验室的研究人员联合起来，提出了紧密结合的心理物理、神经和建模研究，试图确定在双侧植入物中有效编码双耳信息的最佳刺激配置。主要的焦点是耳间时间差(ITD)，因为ITD是声音定位的主要线索，而且双耳在检测方面的优势依赖于ITD。心理物理实验将在双侧植入Clarion设备的人类患者身上进行。神经实验将在耳聋的麻醉猫身上进行，猫双侧植入耳壳内电极阵列。单单位和多单位的记录将从下丘(IC)进行，在那里可以获得关于神经元双耳特性的大量信息。为了明确和定量地检验我们对经验结果的理解，我们还将使用双耳加工模型来预测IC反应和心理物理能力，从对电刺激反应的听觉神经活动的描述中预测。其具体目的是(1)确定时间包络和精细结构对ITD编码在电听力中的相对有效性；(2)确定1TD灵敏度如何依赖于刺激电极的耳间位置的差异；(3)确定在双侧刺激的噪声中信号检测是否具有双耳优势。这些实验的一个重要目标是测试一种新的处理策略，该策略寻求通过使用持续的、高速的、去同步的脉冲序列作为载波波形来改善刺激波形在听觉神经元时间放电模式中的表示。总体而言，这些研究将提供有关影响电听力中双耳交互作用的刺激参数的基本知识，并可能导致专门适用于双侧人工耳蜗植入的新处理器设计。

DESCRIPTION (provided by applicant): Binaural hearing is essential for accurate sound localization and for hearing out sounds of interest among competing sound sources, and these binaural advantages are an important motivating factor for the increasing number of bilateral cochlear implants. In this application, investigators from three laboratories at the Massachusetts Eye and Ear Infirmary, MIT, and Boston University join together to propose closely integrated psychophysical, neural and modeling studies that seek to identify the best stimulus configurations for effectively encoding binaural information in bilateral implants. The primary focus is on interaural time differences (ITD) because ITD is a dominant cue for sound localization, and because binaural advantages in detection depend on ITD. The psychophysical experiments will be conducted in human patients implanted bilaterally with Clarion devices. The neural experiments will be conducted in deafened, anesthetized cats implanted bilaterally with intracochlear electrode arrays. Single and multi-unit recordings will be made from the inferior colliculus (IC), for which a great deal of information is available on binaural properties of neurons. In order to explicitly and quantitatively test our understanding of the empirical results, we will also use models of binaural processing to predict both IC responses and psychophysical abilities from descriptions of auditorv nerve activity in response to electric stimulation. The specific aims are to (1) determine the relative effectiveness of temporal envelope and fine structure for ITD coding in electric hearing, (2) determine how 1TD sensitivity depends on interaural disparities in cochlear locations of the stimulating electrodes, (3) determine whether there is a binaural advantage for signal detection in noise with bilateral stimulation. An important goal of these experiments will be to test a novel processing strategy that seeks to improve the representation of the stimulus waveform in temporal discharge patterns of auditory neurons by using an ongoing, high-rate, desynchronizing pulse train as the carrier waveform. Overall, these studies will provide basic knowledge about the stimulus parameters that influence binaural interactions in electric hearing and are likely to lead to new processor designs specifically adapted to bilateral cochlear implants.