Influence of moderate hearing loss on auditory perception & cortical processing

描述（由申请人提供）：许多听觉感知技能在漫长的过程中成熟（在人类中），直到青少年时期。如果听力在发育过程中受到干扰，可能会出现听觉感知和语言习得方面的长期缺陷。令人惊讶的是，支持后期出现的感知技能的听觉编码特性的成熟在很大程度上是未知的；我们所知道的仅仅是基于麻醉动物的录音。这也是为什么我们对轻度至中度听力损失对中枢听觉成熟的影响的理解尚不确定的原因。为了解决这些问题，我将首次研究清醒动物的功能发展，并探索听觉编码特性如何受到感官经验的影响。核心假设是，发育期间的中度听力损失破坏了听觉皮层（ACx）的编码特性，导致听觉感知表现的可测量缺陷。AIM 1将确定发育性传导性听力损失是否会破坏成年沙鼠的感知能力。动物将接受两项任务的测试，而在人类中，这两项任务已知有不同的成熟速度，并会受到听力损失的影响。这些包括检测正弦振幅（sAM）和调频（sFM）信号。AIM 2将确定在幼年发育期间进行听觉任务训练是否可以挽救传导性听力损失饲养的动物的正常感知行为。AIM 3将描述在AIM 1中检查的感知基础上的神经编码特性的正常发育速度，并将评估这些编码特性是否以与AIM 1中检查的感知缺陷相关的方式受到干扰。在耳蜗成熟后的发育期间，将从清醒动物的ACx中获得单单位记录。广泛的目标是确定编码特性是否以不同的速度成熟，正如行为研究所表明的那样，并确定sAM或sFM编码是否容易受到早期听力损失的影响。总之，这些数据将提供对清醒发育动物的听觉编码的首次分析，并揭示中度听力损失是否会破坏感知技能和支持它们的编码特性。

DESCRIPTION (provided by applicant): Many auditory perceptual skills mature over a long time course (in humans), well into the teenage years. If hearing is disrupted during development, there may be long-lasting deficits in auditory perception and language acquisition. Surprisingly, maturation of the auditory coding properties that support late-emerging perceptual skills are largely unknown; what little we do know is based solely on recordings from anesthetized animals. This is also why our understanding of the effect of mild to moderate hearing loss on central auditory maturation is unsettled. To address these issues, I will examine functional development in awake animals for the first time, and explore how auditory coding properties are influenced by sensory experience. The central hypothesis is that moderate hearing loss during development disrupts coding properties in the auditory cortex (ACx), leading to measurable deficits in auditory perceptual performance. There are three related aims: AIM 1 will determine whether developmental conductive hearing loss disrupts the perceptual abilities of adult gerbils. Animals will be tested on two tasks that, in humans, are known to have different rates of maturation and to be affected by hearing loss. These include detection of sinusoidal amplitude (sAM) and frequency modulated (sFM) signals. AIM 2 will determine whether training on an auditory task during juvenile development can rescue normal perceptual behavior in animals reared with conductive hearing loss. AIM 3 will characterize the normal rate of development of neural coding properties underlying the percepts examined in Aim 1, and will assess whether these coding properties are perturbed in a manner that correlates with perceptual deficits examined in AIM 1. Single unit recordings will be obtained from the ACx of awake animals during the period of development that follows cochlear maturation. The broad goals are to determine whether coding properties mature at different rates, as suggested by behavioral studies, and to determine whether sAM or sFM coding is vulnerable to early hearing loss. Together, these data will provide the first analysis of auditory coding in awake developing animals, and reveal whether moderate hearing loss disrupts both perceptual skills and the coding properties that support them. PUBLIC HEALTH RELEVANCE: Profound hearing loss in children can produce long-lasting deficits in auditory perception and language acquisition, and it has been suggested that mild to moderate hearing loss, including that commonly associated with middle ear infections, might also impact auditory performance. To address this question, we will induce conductive hearing loss in developing animals, and study their behavioral performance and central auditory nervous system function as adults. Thus, this study will examine whether moderate hearing loss disrupts both perceptual skills and the neural coding properties that support them.