Functional Organization of Primary Auditory Cortex

描述(申请人提供)：提出的实验的长期目标是确定基本的处理原则和策略，这些原则和策略构成了听觉皮层接受场转换和复杂声音表征的基础。我们建议对比和比较成年食肉动物(Felis Catus)和觉醒松鼠猴(Saimiri Cerureus)的两个主要听觉区域的组织，特别是功能域和板层组织。一个主要前提是，核心区域在很大程度上接受独立的输入，并表现出特定的功能差异，这些差异可能构成特定于任务的处理流。这些问题是：输入在来源位置和功能特性上有何不同；丘脑输入对皮质感受野(RF)多样性的产生有何贡献；皮质输入水平的功能特征与输出层的功能特征相比如何？这项拟议工作背后的主要假设是：(I)与皮质下站相比，初级听觉皮质场中的神经元表现出新颖的、紧急的处理特性(“在哪里”问题)；(Ii)这些紧急特征是由丘脑皮质和皮质相互作用产生的(“如何”问题)；(Iii)在每个皮质神经元中表达多个刺激维度，并控制有助于向更健壮、变化较小的声音表示的转换的非线性相互作用(“什么”问题)。基于信息论的频谱-时间感受场(STRF)估计方法表明，听觉前脑中出现了新的刺激处理特性。这些特性与初级视皮层简单和复杂细胞的突现加工特征有一些相似之处。我们的目标是描述这些特征，并比较它们在不同皮层区域和不同物种中的特性，以推断它们的一般特性及其对人类听力的潜在贡献。目标1将评估多特征感受场的参数分布及其在听觉丘脑和听觉皮质核心区的非线性。目标2将确定在听觉皮质神经元中产生多个特征维度的主要来源。目标3将确定多特征、非线性神经元处理模型预测对输入刺激组合和噪声中的信号的反应有多好。将这些研究结合起来，将建立初级听觉皮质区域信号处理的功能框架。了解这些原理对于系统评估同时存在的皮质上行和下行通路、它们在正常听觉处理中的作用、在知觉学习中的作用以及它们对听觉障碍的贡献是至关重要的。

DESCRIPTION (provided by applicant): The long-term goal of the proposed experiments is to identify the fundamental processing principles and strategies that underlie auditory cortical receptive field transformations and the representations of complex sounds. We propose to contrast and compare the organization of two primary auditory fields in adult carnivores (Felis catus) and the awake squirrel monkey (Saimiri sciureus) with specific reference to functional domains and laminar organization. A main premise is that core areas receive largely independent inputs and exhibit specific functional differences that may constitute task-specific processing streams. The questions are how do the inputs differ in source location and functional properties; what do the thalamic inputs contribute to the generation of cortical receptive field (RF) diversity; and how do the functional characteristics at the cortical input level compare to those in the output layers? The principal hypotheses underlying the proposed work are that (i) neurons in primary auditory cortical fields express novel, emergent processing properties compared to subcortical stations (the "where" question); (ii) these emergent features are generated by thalamocortical and corticocortical interactions (the "how" question); (iii) multiple stimulus dimensions are expressed in each cortical neuron and govern nonlinear interactions that contribute to transformations toward a more robust, less variant sound representation (the "what" question). Information-theory based methods of spectro-temporal receptive field (STRF) estimation suggest the emergence of novel stimulus processing properties in the auditory forebrain. These properties bear some similarities to emergent processing features in simple and complex cells of primary visual cortex. The goal is to characterize these features and compare their properties across cortical fields and across species in order to extrapolate their general properties and their potential contributions to human hearing. Aim 1 will assess the parameter distributions of the multiple-feature receptive fields and their nonlinearities in auditory thalamus and auditory cortical core areas. Aim 2 will determine the main contributing sources to the generation of multiple feature dimensions in auditory cortical neurons. Aim 3 will determine how well a multi-feature, nonlinear model of neuronal processing predicts responses to combinations of input stimuli and to signals in noise. Combined these studies will establish a functional framework of signal processing in primary auditory cortical fields. Understanding these principles is crucial for a systematic evaluation of concurrent cortical ascending and descending pathways, their role in normal auditory processing, in perceptual learning, and their contributions to auditory disorders.