Neural Correlates of Streaming of Complex Sounds

描述（由申请人提供）：本研究的长期目标是解释听觉系统如何分析复杂的声音“场景”，其中多个声音“流”（例如并发的声音）相互作用并争夺注意力。这个项目将研究注意力对简单和复杂声音流的神经反应的影响。该方法包括同时对雪貂进行单单元记录和行为任务，以及对人类进行心理物理测量。在不同的注意条件下，包括全局注意和选择性注意，将测量雪貂听觉皮层的不同区域（跨越初级或“核心”和次级或“带”区域）对声音流的神经反应。动物的注意力状态将通过人类听觉流感知的心理物理测量激发的行为任务来操纵。这些任务的设计方式要求动物能够有选择地关注当前的一种声音流，或整体关注整个听觉刺激，或关注视觉刺激。通过比较不同注意力条件下的神经反应，将有可能评估注意力如何影响听觉皮层不同部分对听觉流的神经反应，更一般地说，听觉流的神经表征是否以及如何在听觉皮层的初级和次级区域形成和处理。雪貂的这些神经生理和行为测量将与人类的心理声学测量相平行和扩展，使用相同或不同的刺激和任务。首先，这项研究将针对具有简单频谱和时间特征的刺激，即纯音序列（Specific Aim 1），以弥补与早期听觉流神经基础研究的差距。在提案的后半部分（具体目标2），这种方法将扩展到光谱复杂的音调，这与生态更相关。这项研究对健康有着直接而重要的影响，因为听力受损的人（包括助听器或人工耳蜗的佩戴者）最常见的抱怨之一是，他们发现很难区分并发的声音流，也很难在其他声音流中有选择地注意其中的一种声音流（比如某人的声音）。更清楚地了解分离和关注听觉流的感知能力的机制，可能会更清楚地了解这些选择性听力困难的起源，并可能启发设计更有效的声音分离算法，用于助听器、人工耳蜗和自动语音识别设备。

DESCRIPTION (provided by applicant): The long-term goal of this research is to explain how the auditory system analyzes complex acoustic "scenes", in which multiple sound "streams" (e.g., concurrent voices) interact and compete for attention. This project will investigate the influence of attention on neural responses to streams of simple and complex sounds. The approach involves a combination of simultaneous single-unit recordings and behavioral tasks in ferrets, and psychophysical measures in humans. Neural responses to sound streams will be measured in different fields of the ferret auditory cortex (spanning both primary or "core" and secondary or "belt" areas) under different attentional conditions, including both global and selective attention. The animal's attentional state will be manipulated using behavioral tasks inspired by psychophysical measures of auditory stream perception in humans. These tasks are designed in such a way that correct performance in them requires that the animal be able to attend selectively to one of the sound streams present, or globally to the whole auditory stimulus, or to a visual stimulus. By comparing neural responses under different attentional conditions, it will be possible to assess how attention influences neural responses to auditory streams in different parts of the auditory cortex and, more generally, whether and how neural representations of auditory streams are formed and processes in primary and secondary areas of auditory cortex. These neurophysiological and behavioral measures in ferrets will be paralleled and extended by psychoacoustical measures in humans, using the same or different stimuli and tasks. This will be done, firstly, for stimuli with simple spectral and temporal characteristics, i.e., pure-tone sequences (Specific Aim 1), in order to bridge the gap with earlier studies of the neural basis of auditory streaming. In the second half of the proposal (Specific Aim 2), this approach will be extended to spectrally complex tones, which are more ecologically relevant. This research has direct and significant health implications, because one of the most common complaints of hearing-impaired individuals (including wearers of hearing aids or cochlear implants) is that they find it difficult to separate concurrent streams of sounds, and to attend selectively to one of these streams (such as someone's voice) among other streams. A clearer understanding of the mechanisms underlying the perceptual ability to separate, and attend to, auditory streams will likely lead to a clearer understanding of the origin of these selective-listening difficulties, and it may inspire the design of more effective sound-separation algorithms for use in hearing aids, cochlear implants, and automatic speech recognition devices.