The Neural Basis of Perceptually-Relevant Auditory Modulations in Humans

描述（由申请人提供）：听觉神经科学的目标之一是了解人类听觉皮层如何分析和编码语音和其他自然声音。一个主要的发现是，感知和语音处理受到声信号的时间调制的关键影响。然而，识别人类的生理机制是分析感知相关的时间调节的基础，这是一个相当大的技术挑战。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，但它们通常局限于单个听觉区域，不能普遍用于人类受试者。脑磁图（MEG）是一种非侵入性工具，适合用于人类，记录来自整个大脑的高速神经信号，但代价是空间分辨率明显较低。幸运的是，最近的研究表明，声学调制的神经编码研究确实可以通过人脑脑电信号对人类受试者进行。因此，脑磁图和细胞外记录都可以采用互补的方式来研究听觉皮层如何编码时间调制。这项研究计划的目标是了解这些声音调制，语言和其他自然声音的组成部分是如何在听觉皮层中编码的。研究编码的声学调制要么嵌入在嘈杂的背景中，如在自然听觉场景中，要么在频率和幅度上都进行独立和同时调制，如在语音中。该研究计划采用平行实验：一组使用MEG记录人类听觉皮层，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、细胞外局部场电位和整个皮层的记录，就有可能统一用于神经编码声学调制的不同方案，包括神经层次的上下。

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.