Encoding of Dynamic Spectrum in Auditory Cortex

描述(由申请人提供)：我们的研究建议调查 初级听觉皮质的反应特性和功能组织 邻近地区，在清醒的雪貂中：具体地说，这项研究试图 确定音色，即声谱的形状是如何表示的 在这些地区的单一单位反应中。我们的研究始于声调和 点击以确定皮质神经元的特征并比较它们的响应特性 以及他们形成的地图与我们和其他人已经在 麻醉后的制剂。NXT，我们使用宽带刺激和正弦 调制光谱包络(也称为波纹)，以表征纯 细胞对宽带响应的时间和纯光谱特性 听起来。细胞对这些涟漪的反应，以及对 通过数据分析，分析了正交波纹组合的响应 基于系统理论的方法，产生听觉单元响应场和 充分描述了它们的光谱和时间特性的线性部分。 这些方法建立在这样的假设之上，即听觉反应 与刺激光谱包络及其动力学成线性关系。 因此，拟议调查的一个基本目标是审查 通过确定单位是否响应于 复杂的声音，如语音，可以从他们对简单的反应中预测出来 涟漪。第二个目标是描述不同类型的 响应非线性的类型，例如阈值、停止波整流、 饱和，以及各种形式的适应。谱的可分性 并且响应字段的时间方面也可以通过比较 细胞对不同类型的声音做出反应。结果将会是 这项研究的出现将加深我们对编码的理解 听觉皮质中复杂的声谱，如语音和音乐。更多 然而，通常情况下，他们会将听觉皮质处理置于 大脑中视觉和其他感觉处理的更大框架，因为 刺激及其背后的理论概念的抽象性质。

DESCRIPTION (provided by applicant): Our research proposes to investigate the response properties and functional organization of primary auditory cortex and neighboring areas, in the awake ferret: specifically, the study seeks to determine how timbre, i.e. the shape of the acoustic spectrum, is represented in the single-unit responses in these areas. Our study starts with tones and clicks to characterize cortical neurons and compare their response properties and the maps they form to the results we and others have already obtained in the anesthetized preparation. Nxt, we use broadband stimuli with sinusoidally modulated spectral envelopes (also called ripples), to characterize the purely temporal and purely spectral properties of cells' responses to broadband sounds. The response of cells to these ripples, together with the response to response to combinations of orthogonal ripples are analyzed by data analysis methods based on systems theory which yield auditory units response fields and fully characterize the linear part of their spectral and temporal properties. These methods are founded on the assumption that the auditory responses are linear with respect to the stimulus spectral envelope and its dynamics. Therefore, a fundamental objective of the proposed investigations is to examine the degree of response linearity by determining whether unit responses to complex sounds such as speech can be predicted from their responses to simple ripples. A second objective is to delineate the origin and extent of various types of response nonlinearities such as threshold, halt-wave rectification, saturation, and various forms of adaptation. The separability of the spectral and temporal aspects of the response fields can also be evaluated by comparing the cells response to the different types of sounds. The results that will emerge from this study will enhance our understanding of the encoding of complex acoustic spectra such as speech and music in auditory cortex. More generally, however, they will place auditory cortical processing within the larger framework of visual and other sensory processing in the brain because of the abstract nature of the stimuli and of the theoretical concepts behind them.