The role of sound deprivation on central processing of masking

描述（由申请人提供）：听力受损的听者和人工耳蜗植入体用户面临的一个主要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背景声音能量暂时减少的过程中提取目标信息来完成这一壮举，这一好处被称为调制掩蔽释放（MMR）。MMR在听力受损者中大大减少或不存在。该提案旨在确定MMR的行为和神经机制，并研究声音剥夺如何影响它们。我相信，这项提案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。听力受损的听众所面临的一些困难不仅来自于感觉输入的退化，而且来自于沿着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，必要的第一步是探索如何检测噪声中的音调是由人类听觉处理的模式生物，蒙古沙鼠（长爪沙鼠）。我们缺乏全面的知识，可能会连接感知和神经元活动与MMR。通过结合心理声学和清醒动物体内生理记录的经验方法，我的主要目标是提高我们对声音剥夺中枢听觉系统如何处理具有挑战性的任务（如MMR）的理解。首先，我将训练声音剥夺的动物在噪音背景中检测音调，并将它们的表现与正常听力对照组进行比较。其次，我将测量这些受过训练的动物的核心听觉皮层的神经元活动。放电模式将揭示控制如何检测波动的背景声音中的音调，以及CHL中是否发生与听力损失相关的行为缺陷相关的改变的放电模式。总的来说，这个建议将评估声音剥夺如何影响MMR在知觉和皮层处理水平。这些结果有望大大促进我们对听力受损者中枢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.