Encoding of Dynamic Spectrum in Auditory Cortex

描述（由申请人提供）：我们的研究计划调查 初级听觉皮层的反应特性和功能组织， 邻近地区，在清醒的雪貂：具体来说，这项研究旨在 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。我们的研究从音调开始， 点击来表征皮层神经元并比较它们的反应特性 以及它们所形成的地图与我们和其他人已经在 麻醉制剂。NXT，我们使用宽带刺激， 调制的频谱包络（也称为波纹），以表征纯 细胞对宽带响应的时间和纯谱特性 声音.细胞对这些波纹的反应，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位响应场， 充分表征其光谱和时间特性的线性部分。 这些方法是建立在这样的假设上的，即听觉反应是 相对于刺激频谱包络及其动态是线性的。 因此，拟议调查的一个基本目标是审查 响应线性度，通过确定装置是否响应 复杂的声音，如语音，可以从他们对简单声音的反应中预测出来。 涟漪第二个目标是描述各种不同的起源和范围， 响应非线性的类型，例如阈值，半波整流， 饱和和各种形式的适应。谱的可分性 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作出反应。结果将 从这项研究中产生的将加强我们对编码的理解， 复杂的声学频谱，如听觉皮层中的语音和音乐。更 然而，一般来说，他们会把听觉皮层处理放在大脑皮层中， 由于大脑中视觉和其他感官处理的更大框架， 刺激的抽象本质和它们背后的理论概念。

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.