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竞争声源中听出感兴趣的声音至关重要，这些双耳优势是双侧人工耳蜗植入数量增加的重要激励因素。在本申请中，来自马萨诸塞州眼耳医院、麻省理工学院和波士顿大学三个实验室的研究人员共同提出了紧密结合的心理物理、神经和建模研究，旨在确定最佳刺激配置，以有效地编码双侧植入物中的双耳信息。主要关注的是耳间时间差（ITD），因为ITD是声音定位的主要线索，因为双耳检测的优势取决于ITD。心理物理学实验将在双侧植入Clarion器械的人类患者中进行。神经实验将在双侧植入脑内电极阵列的麻醉猫中进行。单个和多个单位的记录将从下丘（IC），其中大量的信息是可用于双耳的神经元的属性。为了明确和定量地测试我们对经验结果的理解，我们还将使用双耳处理模型来预测IC反应和心理物理能力，这些反应来自对电刺激的反应的神经活动的描述。具体目标是：（1）确定电听觉中ITD编码的时间包络和精细结构的相对有效性，（2）确定ITD灵敏度如何取决于刺激电极耳蜗位置的耳间差异，（3）确定双侧刺激在噪声中的信号检测是否具有双耳优势。这些实验的一个重要目标将是测试一种新的处理策略，该策略旨在通过使用正在进行的、高速率的、去噪声化的脉冲串作为载波波形来改善听觉神经元的时间放电模式中的刺激波形的表示。总的来说，这些研究将提供有关影响电听觉中双耳交互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体的新处理器设计。

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.