Effects of auditory nerve degeneration on midbrain coding and perception in noise

描述（由申请人提供）：最近的研究表明，听神经变性与正常衰老和噪音引起的“暂时性”听力损失有关。虽然老年听众和有噪音过度暴露史的人的听觉神经退化可能导致这些群体的感知困难，但这一假设目前尚未得到证实。这些群体中的个体通常报告在真实世界的听力条件下理解语言有很大困难。这项提议的研究将检验一个假设，即听神经退化会导致中枢处理的不利变化，最终降低对背景噪声中复杂信号的感知。由于虎皮鹦鹉具有与人类相似的感知能力，研究人员将在虎皮鹦鹉身上进行来自中脑听觉的平行神经生理学记录和涉及背景噪音中复杂刺激的行为实验。声音刺激将包括语音符号和自然虎牙的叫声。K99指导的研究将使用平行的神经生理学和行为方法来识别中脑中的功能细胞类别，这些细胞有助于正常听力动物的强大感知能力。在提高了我们对正常听觉感知的认识之后，R00的独立研究将量化中脑编码和听觉神经退化对噪音的感知的变化。基于先前的研究结果，kainic酸将诱导听神经变性，该药物选择性地破坏神经纤维，同时保持耳蜗毛细胞完整。这项研究的结果有望

DESCRIPTION (provided by applicant): Recent studies show that auditory-nerve degeneration is associated with both normal aging and noise-induced "temporary" hearing loss. Though auditory-nerve degeneration in older listeners and individuals with a history of noise overexposure may contribute to perceptual difficulties in these groups, this hypothesis is currently unexplored. Individuals in these groups commonly report great difficulty understanding speech under real- world listening conditions. The proposed research will test the hypothesis that auditory-nerve degeneration causes adverse changes in central processing that ultimately degrade perception of complex signals in background noise. Parallel neurophysiological recordings from the auditory mid-brain and behavioral experiments involving complex stimuli in background noise will be conducted in the budgerigar because this avian species has human-like perceptual capabilities. Acoustic stimuli will include speech tokens and natural budgerigar calls. The K99 mentored research will use parallel neurophysiological and behavioral approaches to identify functional cell classes in the mid-brain that contribute to robust perceptual abilities in normal-hearing animals. Having advanced our knowledge of normal-hearing perception, the R00 independent research will quantify changes in mid-brain coding and perception in noise with auditory-nerve degeneration. Auditory-nerve degeneration will be induced with kainic acid based on previous results showing that this agent selectively damages nerve fibers while leaving cochlear hair cells intact. The results of this research are expected to have high impact because they will quantify, possibly for the first time, the perceptual consequences of auditory-nerve degeneration under real-world listening conditions. Furthermore, the parallel physiological and behavioral data provided by this work are expected to provide unique insight into the physiological changes underlying perceptual difficulties. Ultimately, this knowledge can help guide new technologies and treatment strategies aimed at restoring performance in people with speech perception problems in noise. The K99 mentored phase of the proposed research will aid in the candidate's career development by expanding his previous neurophysiological training in auditory-nerve fiber recordings into the central auditory system. Furthermore, the candidate will gain valuable new skills in animal psychoacoustics. The University of Rochester is an excellent environment for the K99 research because this institution has an active systems neuroscience community including the Sponsor and other key faculty. The new combination of skills provided by this work will allow the candidate to achieve his goal of using parallel physiological and behavioral approaches to help pinpoint the physiological changes underlying human communication problems.