The role of sound deprivation on central processing of masking

描述(申请人提供)：对于听力受损的听者和人工耳蜗使用者来说，一个主要的挑战是在有背景声音的情况下检测和理解语音。当背景能量是非平稳的并且随时间波动时，在背景噪声中检测目标声音通常更容易。听力正常的听众可以通过在暂时降低背景声能期间提取目标信息来实现这一壮举，这一好处被称为调制掩蔽释放(MMR)。在听力受损的人中，MMR明显减少或缺失。这项建议旨在确定MMR的行为和神经机制，并研究声音剥夺对它们的影响。我相信，这项提议的结果将大大加深我们对听力损失如何影响我们对抗掩蔽的能力的理解，并有助于制定听力损失的补救策略。听力受损的听众面临的一些困难不仅源于感官输入的退化，还源于沿整个神经轴的中枢听觉系统的改变。由于声音剥夺对MMR的影响知之甚少，有必要的第一步是探索人类听觉处理的模式生物--蒙古沙鼠如何在噪声中检测音调。我们缺乏可能与MMR相关的知觉和神经元活动联系起来的全面知识。通过结合心理声学的经验方法和清醒动物的体内生理学记录，我的关键目标是提高我们对声音剥夺的中央听觉系统如何处理MMR等具有挑战性的任务的理解。首先，我将训练缺乏声音的动物在噪音背景中检测音调，并将它们的表现与正常的听力控制进行比较。其次，我将测量这些受训动物的核心听觉皮质中的神经元活动。放电模式将揭示对照组如何在波动的背景声音中检测音调，以及CHL中是否发生与听力损失相关的行为缺陷的放电模式改变。总的来说，这项建议将评估声音剥夺如何在知觉和大脑皮层处理水平上影响MMR。这一结果有望极大地促进我们对听力受损人群中央处理缺陷的起源和范围的理解。

DESCRIPTION (provided by applicant): A major challenge for hearing-impaired listeners and cochlear implant users is to detect and understand speech in situations with background sound. Detecting a target sound in background noise is often easier when the background energy is non-stationary and fluctuates over time. Normal-hearing listeners can accomplish this feat by extracting target information during temporary reductions in background sound energy, a benefit known as modulation masking release (MMR). MMR is much reduced or absent in the hearing impaired. This proposal aims to identify behavioral and neuronal mechanisms for MMR, and examine how sound deprivation affects them. I believe that the results emanating from this proposal will considerably further our understanding of how hearing loss affects our capacity to combat masking, and help develop remediation strategies for hearing loss. Some of the difficulties facing hearing-impaired listeners stem not only from degraded sensory input but also from an altered central auditory system along the entire neuraxis. Because the effect of sound deprivation on MMR is poorly understood, a necessary first step is to explore how the detection of tones in noise is performed by a model organism of human auditory processing, the Mongolian gerbil (Meriones unguiculatus). We lack comprehensive knowledge that may link perception and neuronal activity associated with MMR. By combining empirical approaches in psychoacoustics and in-vivo physiology recordings from awake animals, my key goal is to improve our understanding on how the sound deprived central auditory system processes a challenging task such as MMR. First, I will train sound-deprived animals to detect a tone in noise backgrounds, and compare their performance to normal-hearing controls. Second, I will measure neuronal activity in core auditory cortex from these trained animals. The discharge patterns will reveal how controls detect a tone in fluctuating background sound and whether altered discharge patterns occur in CHL that correlate with hearing- loss related behavioral deficits. Collectively, this proposal will assess how sound deprivation affects MMR at both perceptual and cortical processing levels. The results are expected to significantly advance our understanding of the origins and scope of central processing deficits amongst the hearing impaired.