Developmental effects of early hearing loss on auditory information processing

项目总结 双耳听力可以准确和精确地定位声音，也赋予了复杂的优势 工作场所、教室、餐馆等竞争语音流、嘈杂的环境 背景和回响比比皆是。不幸的是，不断增长的人口，从婴儿期到 老年人和各种病因，在这种环境中经历严重的困难，尽管有正常的 测听阈值。这种困难是中枢性听觉处理障碍(CAPD)的一个标志，它 指在中枢听觉系统中处理声学信息的困难，表现为不良 听力表现，通常特别是在双耳听力任务中。因此，可能会出现类似CAPD的挑战 暂时性传导性听力损失、衰老、创伤性脑损伤、自闭症、神经退行性疾病 (多发性硬化症)和使用双边临床设备(助听器、人工耳蜗)。其后果是 CAPD可能是严重的；在儿童中，CAPD会影响言语和语言学习以及学业成绩 而在成年人中，无论病因如何，生活质量、工作表现、是否适合执行任务、社交等 CAPD的主要局限性是临床诊断是基于一系列症状，其中许多症状是重叠的 与其他发育障碍，如注意缺陷多动障碍，学习障碍和 语言缺陷。此外，听觉处理的行为评估，特别是在儿童和 老年人的信度较差，得分往往反映较高水平的认知或分析过程 而不是基本的听觉感官处理。因此，及早干预和实施康复战略 在CAPD患者中是被排除的。跨越这一障碍的一个潜在方法是使用非侵入性 电生理测量。听性脑干反应(ABR)在全世界范围内用于新生儿和 成人听力筛查。因为不同的ABR波大体上代表了脑部不同部分的活动 听觉通路，可以用来评估通路不同阶段的功能状态 适当的刺激。可以使用双耳交互作用分量(BIC)来评估双耳阶段 ABR.BIC是单耳诱发的ABR减去双耳诱发的ABR后的剩余ABR ABR。先前的研究已经确定BIC是一个潜在的双耳能力的生物标志物。正如BIC可以做到的那样 使用大多数听力学诊所已有的设备和方法进行测量，其发展为 诊断工具可能具有直接和广泛的临床价值。然而，尽管比较研究已经 在各种模式物种中，关于人类BIC的报道令人困惑地多种多样，而且 不可靠。拟议的研究包括三个目的，以建立对 BIC，包括1)确定其脑干回路来源，2)确定可变性的来源 包括人类在内的哺乳动物物种，3)确定人类BIC测量的最佳做法，以及 评估BIC作为预测人类双耳知觉有意义的方面的生物标志物。

PROJECT SUMMARY Binaural hearing allows accurate and precise localization of sounds, and also confers advantages in complex environments such as workplaces, classrooms, restaurants, etc. where competing speech streams, noisy backgrounds, and reverberation abound. Unfortunately, an increasing population, spanning infancy through elderly and of diverse etiology, experiences severe difficulty in such environments despite having normal audiometric thresholds. Such difficulties are a hallmark of Central Auditory Processing Disorder, CAPD, which refers to difficulties in processing acoustic information in the central auditory system as demonstrated by poor hearing performance, often specifically in binaural hearing tasks. CAPD-like challenges can emerge as a result of temporary conductive hearing loss, aging, traumatic brain injury, autism, neurodegenerative diseases (multiple sclerosis) and use of bilateral clinical devices (hearing aids, cochlear implants). The consequences of CAPD can be severe; in children, CAPD impacts speech and language learning and academic performance and in adults, quality of life, job performance, fitness for duty, social interactions, etc. Regardless of etiology, a major limitation in CAPD is that clinical diagnosis is based on a cluster of symptoms, many of which overlap with other developmental disorders such as attention deficit hyperactivity disorder, learning disabilities and language deficits. Moreover, behavioral assessments of auditory processing, particularly in children and elderly, have poor reliability with scores often reflecting higher-level cognitive or analytical processes rather than basic auditory sensory processing. Thus, early intervention and implementation of rehabilitation strategies in CAPD patients is precluded. A potential way to surmount this barrier is to use non-invasive electrophysiological measures. Auditory brainstem responses (ABRs) are used worldwide for newborn and adult hearing screening. Because different ABR waves broadly represent activity within different parts of the auditory pathway, it is possible to assess the functional state of distinct stages of the pathway using appropriate stimuli. Binaural stages can be assessed using the binaural interaction component (BIC) of the ABR. The BIC is the residual ABR obtained after subtracting the sum of monaurally- from binaurally-evoked ABRs. Prior research has identified the BIC as a potential biomarker for binaural ability. As the BIC can be measured using equipment and methods already available in most audiology clinics, its development as diagnostic tool could have immediate and widespread clinical value. However, while comparative studies have reported robust BIC in a variety of model species, reports of human BIC are perplexingly variable and unreliable. The proposed research comprises three Aims to establish a comprehensive understanding of the BIC, including 1) identification of its brainstem circuit origin, 2) identification of sources of variability across mammalian species including humans, 3) identification of best practices in human BIC measurement, and assessment of the BIC as a biomarker for predicting meaningful aspects of human binaural perception.