The Neural Basis of Perceptually-Relevant Auditory Modulations in Humans

描述(申请人提供)：听觉神经科学的目标之一是了解语音和其他自然声音是如何在人类听觉皮质中分析和编码的。一个主要的发现是，感知和语音处理受到声音信号中的时间调制的关键影响。然而，在人类中识别分析知觉相关的时间调制的生理机制面临着相当大的技术挑战。细胞外记录方法是研究基于时间的神经编码机制的理想方法，但它们通常限于单个听觉区域，不能在人类受试者中普遍使用。脑磁图(MEG)是一种非侵入性的工具，适合于人类使用，记录来自整个大脑的高速神经信号，尽管代价是空间分辨率明显变得粗糙。幸运的是，最近的工作表明，确实可以使用脑磁图对人类受试者进行声学调制神经编码的研究。因此，脑磁图和细胞外记录都可以用互补的方式来研究听觉皮质如何对时间调制进行编码。这项拟议的研究计划的目标是了解这些声学调制、语音的构建块和其他自然声音是如何在听觉皮质中编码的。研究其编码的声学调制要么嵌入在噪声背景中，如在自然听觉场景中，要么在频率和幅度上独立地和同时地调制，如在语音中。该研究计划采用了几组平行的实验：一组使用脑磁图从人类听觉皮质进行记录，另一组使用动物模型的细胞外记录方法。有了来自单个神经元、细胞外局部场势和整个大脑皮层的记录，就有可能统一用于在神经层级上下对声学调制进行神经编码的不同方案。 与公共健康相关：最近的研究表明，各种听力和认知障碍是由声音的时间处理问题引起的(例如，发育性语言障碍，以及因衰老、听神经病或人工耳蜗术而造成的听力障碍)。目前的工作将提供新的实验方法，以及丰富的关于正常人大脑皮质时间处理的经验数据库，然后可以用于临床环境。

DESCRIPTION (provided by applicant): One of the goals of auditory neuroscience is to understand how speech and other natural sounds are analyzed and encoded in the human auditory cortex. One major finding is that perception and speech processing are crucially affected by temporal modulations in the acoustic signal. However, identifying in humans the physiological mechanisms that underlie the analysis of perceptually-relevant temporal modulations presents a considerable technical challenge. Extracellular recording methods are ideal for the investigation of time-based neural coding mechanisms, but they are typically limited to a single auditory area and cannot be generally used in human subjects. Magnetoencephalography (MEG) is a non-invasive tool, suitable for use in humans that records high-speed neural signals from the entire brain, though at the cost of significantly coarser spatial resolution. Fortunately, recent work has shown that investigations of the neural coding of acoustic modulations can indeed be conducted using MEG with human subjects. Thus MEG and extracellular recording can both be employed, in complementary ways, to investigate how temporal modulations are encoded by auditory cortex. The goal of this proposed research program is to understand how these acoustic modulations, the building blocks of speech and other natural sounds are encoded in auditory cortex. The acoustic modulations whose encoding is investigated are either embedded in a noisy background, as in a natural auditory scene, or modulated in both frequency and amplitude, independently and simultaneously, as in speech. The research program employs parallel sets of experiments: one set using MEG to record from human auditory cortex, and the other using extracellular recording methods in an animal model. With recordings from individual neurons, from the extracellular local field potential, and from the whole cortex, it may be possible to unify the different schemes used to neurally encode acoustic modulations, up and down the neural hierarchy. PUBLIC HEALTH RELEVANCE: Recent research suggests that a variety of hearing and cognitive impairments result from problems in temporal processing of sounds (e.g. developmental language disorders, and hearing impairment due to aging, auditory neuropathy, or cochlear implants). The present work will provide novel experimental approaches, as well as a rich empirical database on cortical temporal processing in normal human subjects, that can then be used in clinical settings.