Effects of Early Conductive Hearing Loss on Auditory Behavior and Information Pro

描述（由申请人提供）：在发育过程中导致传导性听力损失（CHL）的慢性耳部感染可导致听觉功能的长期缺陷，包括双耳听力。这些障碍包括在空间中定位声音的障碍，在嘈杂的环境中探测声音的障碍，以及语音和语言的习得障碍——所有这些任务都需要适当地整合来自双耳的信息。特别是，声音位置的线索，包括耳间时间（ITD）和水平（ILD）差异线索，严重依赖于双耳声音信息的适当输入。由于CHL可以衰减和延迟传入的声音，因此声音位置的线索可以有效地改变。在生命早期发育敏感时期出现CHL可能导致双耳听觉系统适应改变的双耳线索而不是正常的线索，从而为临床观察到的儿童持续性空间听力问题提供了可能的基础。然而，这些持续效应背后的确切机制尚不完全清楚。一些动物研究试图阐明听觉系统发育中的中枢机制，但很少有人全面研究早期CHL的长期行为后果，也没有人充分研究其对声音定位线索的神经信息处理的影响。因此，本研究的主要目的是了解早期CHL对(1)行为声音定位能力和(2)声音定位敏感神经元信息处理的影响。为了实现这些目标，本研究的具体目的是：(1)评估单侧CHL饲养的成年豚鼠的行为声音定位能力；(2)评估单侧CHL饲养的同种动物的下丘神经元的信息处理能力。实验将结合行为学和体内电生理技术，共同评估早期CHL对双耳听觉系统的影响。我们假设与正常对照动物相比，早期CHL会导致持续的声音定位缺陷，以及损伤

DESCRIPTION (provided by applicant): Chronic ear infections resulting in a conductive hearing loss (CHL) during development can produce long-term deficits in auditory functions, including those involved with binaural hearing. These include impairment in locating sounds in space, detecting sounds in noisy environments, as well as acquisition of speech and language- all tasks that require the proper integration of information from both ears. In particular, the cue to sound location, which include interaural time (ITD) and level (ILD) difference cues, rely heavily on the proper input of sound information from both ears. Since CHL can attenuate and delay incoming sounds, the cues to sound location can thus be effectively altered. The presence of a CHL during developmental sensitive periods early in life may result in the binaural auditory system adapting to altered binaural cues to location instead of the normal cues, thus providing a possible basis for the persistent spatial hearing problems observed clinically in children. The exact mechanism underlying these persistent effects, however, is not entirely known. Several animal studies have attempted to elucidate the central mechanisms in the developing auditory system, yet few have comprehensively examined the long-term behavioral consequences of early CHL, and none have fully examined its effects on neural information processing of cues to sound location. Therefore, the main goal of this research is to understand the effects of early CHL on (1) behavioral sound localization ability and (2) information processing by neurons sensitive to sound location. Towards these goals, the Specific Aims of the proposed research are to (1) assess behavioral sound localization ability in adult guinea pigs reared with a unilateral CHL and (2) to evaluate the information processing capabilities of neurons in the inferior colliculus (IC) in the same animals reared with a unilateral CHL. Experiments will integrate both behavior and in vivo electrophysiological techniques to jointly assess the effects of early CHL on the binaural auditory system. We hypothesize that early CHL will result in persistent sound localization deficits relative to normal control animals, as well as an impairment in neural information processing of the ILD cue to sound location. In general, we expect greater behavioral deficits to be associated with a reduction in ILD information processing, and that this may provide a possible basis for the persistent spatial hearing deficits observed in children who experienced chronic ear infections early in development. The proposed work is specifically designed to support the mission of NIDCD by advancing the basic understanding of the developing binaural auditory system with clinical relevance to childhood hearing disorders.