Bilateral cochlear implants: Physiology and psychophysics

描述(申请人提供)：双侧人工耳蜗术旨在恢复深度失聪患者双耳听力的功能。虽然双侧植入物的佩戴者在噪音中表现出更好的声音定位和语音接收，但他们处理耳间时间差(ITD)的能力仍远未正常，导致双耳收益低于日常声学环境中的正常水平。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研究人员结合了他们在心理物理学、神经生理学和神经计算方面的专业知识，以期对双侧人工耳蜗术中的ITD过程有一个基本的了解。双侧植入人体受试者的心理物理实验将与双侧植入耳廓内电极阵列的聋猫下丘的单单位记录平行进行。具体目的是(1)比较不同耳聋发病年龄和耳聋持续时间的动物的神经ITD敏感性，以测试剥夺双耳经验是否对ITD敏感性有影响，以及这些影响是否存在一个关键期；(2)表征电极相互作用对神经和行为ITD敏感性的影响，以了解当通过处理器收听和存在多声源时，ITD是如何在多通道刺激下处理的；(3)建立双耳脑干神经元模型以了解双侧植入对神经ITD敏感性的机制，并建立神经元群体活动模式的模型以预测心理物理表现，并比较从群体活动估计刺激ITD的各种策略的有效性。这些研究将增加我们对神经、心理物理和电极因素如何与双耳经验相互作用的基本理解，以塑造双侧人工耳蜗术后的表现。它们还可能导致用于双侧人工耳蜗术的新的双耳声音处理器，这种处理器在包含多个声源和混响的日常声学环境中工作得更好，并根据患者的双耳经历和剥夺病史而适应特定类型的患者。最后，控制聋、双侧人工耳蜗植入和神经记录的结合为研究双耳系统的可塑性提供了一种新的途径。深度失聪的人越来越多地在双耳接受人工耳蜗植入，希望这种双侧植入将提高他们在噪音中定位声音和理解语音的能力。我们的研究结合了神经生理学、心理学和生物物理学的专业知识，以基本了解双侧植入物的佩戴者在日常情况下面临的挑战，以及性能如何与他们的耳聋病史相互作用。这些研究可能会导致用于双侧植入物的新的电子声音处理器，这种处理器在噪音中工作得更好，更适合特定类型的耳聋病史。

DESCRIPTION (provided by applicant): Bilateral cochlear implantation aims at restoring the functional benefits of binaural hearing to the profoundly deaf. While wearers of bilateral implants show improved sound localization and speech reception in noise, their ability to process interaural time differences (ITD) is still far from normal, resulting in smaller binaural benefits than normal in everyday acoustic environments. In this application, investigators from the Massachusetts Eye and Ear Infirmary, MIT, and Boston University combine their expertise in psychophysics, neurophysiology and neural computation in order to gain a basic understanding of the ITD processing with bilateral cochlear implants. Psychophysical experiments in bilaterally-implanted human subjects will be conducted in parallel with single-unit recordings from the inferior colliculus of deaf cats implanted bilaterally with intracochlear electrode arrays. The specific aims are to (1) compare neural ITD sensitivity in animals differing in age of onset of deafness and duration of deafness in order to test whether deprivation of binaural experience has an effect on ITD sensitivity and whether there is a critical period for these effects; (2) characterize the effects of electrode interactions on both neural and behavioral ITD sensitivity in order to understand how ITD is processed with multi-channel stimulation as occurs when listening through a processor and in the presence of multiple sound sources; (3) develop models for binaural brainstem neurons to understand the mechanisms underlying neural ITD sensitivity with bilateral implants, and models for activity patterns in populations of neurons to predict psychophysical performance, and compare the effectiveness of various strategies for estimating the stimulus ITD from the population activity. These studies will increase our basic understanding of how neural, psychophysical and electrode factors interact with binaural experience in shaping performance with bilateral cochlear implants. They are also likely to lead to new binaural sound processors for bilateral cochlear implants that work better in everyday acoustic environments comprising multiple sound sources and reverberation, and that are adapted to specific types of patients depending on their history of binaural experience and deprivation. Finally, the combination of controlled deafening, bilateral cochlear implantation and neural recording offers a novel approach for studying the plasticity of the binaural system. The profoundly deaf increasingly receive cochlear implants in both ears in the hope that such bilateral implantation will improve their ability to localize sounds and understand speech in noise. Our studies combine expertise from neurophysiology, psychology and biophysics in order to gain a basic understanding of the challenges wearers of bilateral implants face in everyday situations and how performance interacts with their history of deafness. These studies will likely lead to new electronic sound processors for bilateral implants that work better in noise and are better adapted to specific types of deafness histories.