Functional Organization of Primary Auditory Cortex

描述(由申请人提供)：拟议实验的长期目标是确定基本的加工原则和策略，这些原则和策略是复杂声音的皮层感受场转换和表征的基础。我们将对比成年猫的两个主要听域A1和AAF的组织，特别是功能域和板层组织。一个主要的前提是，A1和AAF接受基本上独立的丘脑和皮质输入，并具有特定的功能差异，这些差异可能构成任务特定的加工流。输入在来源位置和功能特性上有何不同；丘脑输入对感受野(RF)多样性的产生有何贡献；大脑皮层输入水平的功能特征如何转化为输出层？在联合电生理学和神经解剖学实验中，将研究功能特性的不同空间分布和这些主要领域的连接模式之间的相互关系。通过将功能特性和大脑皮层连通性联系起来，可以评估简单和复杂声音的大脑皮层表征和转换特征所依据的全球原则。。第一个目标是为简单和复杂的声音定义Al和AAF特定于层的功能组织。我们认为，Illb/IV层中的单个神经元将显示出与其他层细胞在RF属性上的系统性差异。将使用传统刺激以及创建双耳光谱-时间感受场的反向相关方法来获得RFs。我们还将比较麻醉猫的A1和AAF以及清醒松鼠猴子的AI中RF特性的椎板特异性变化，以解决清醒动物中的比较问题和RF组织。第二个目的是通过同时记录猫内侧膝状体和AI/AAF的功能连接神经元对，直接比较丘脑源和皮质靶点的RFs。假设丘脑输入特性与其皮质目标的某些RF特性相似，但许多皮质RFs的构造实质上是由皮质贡献塑造的。最后，我们将把丘脑和皮质内的联系与Al和AAF的功能亚区联系起来。主要的问题是丘脑和皮质的斑片状投射如何与具有光谱、时间和双耳特性的斑块状皮质组织相关。从逆行示踪剂注射到猫AI/AAF生理定义的功能区的标记将根据功能图进行评估。这些研究将建立初级皮质区域信号处理的功能和结构框架。对这些原理的洞察对于理解听觉皮质中的信息流、正常听觉处理和知觉学习的回路以及它们对听觉障碍的贡献至关重要。

DESCRIPTION (provided by applicant): The long-term goal of the proposed experiments is to identify the fundamental processing principles and strategies that underlie the cortical receptive field transformations and representations of complex sounds. We will contrast the organization of two primary auditory fields, Al and AAF, in adult cat with specific reference to functional domains and laminar organization. A main premise is that Al and AAF receive largely independent thalamic and cortical inputs and have specific functional differences that may constitute task specific processing streams. How do the inputs differ in source location and functional properties; what do the thalamic inputs contribute to the generation of receptive field (RF) diversity; and how are the functional characteristics at the cortical input level transformed in the output layers? The interrelations between heterogeneous spatial distributions of functional properties and the connection patterns of these primary fields will be studied in joint electrophysiological and neuroanatomical experiments. By relating the functional properties and cortical connectivity, global principles underlying the characteristics of cortical representations and transformations can be assessed for simple and complex sounds. . The first aim is to define layer-specific functional organizations of Al and AAF for simple and complex sounds. We think that single neurons in layers Illb/IV will show systematic differences in RF attributes from cells in other layers. RFs will be obtained with traditional stimuli as well as with a reverse-correlation method that creates binaural spectro-temporal receptive fields. We will also compare the lamina-specific changes in RF properties in Al and AAF of the anesthetized cat and in AI of the awake squirrel monkey to address comparative questions and RF organization in conscious animals. The second aim is to compare directly the RFs of thalamic sources and cortical targets by simultaneous recording of functionally connected neuron pairs in cat medial geniculate body and AI/AAF. It is hypothesized that thalamic input properties approximate some RF properties of their cortical targets but that construction of many cortical RFs is substantially shaped by corticocortical contributions. Finally, we will relate thalamic and intracortical connections to functional sub-regions of Al and AAF. How patchy thalamic and corticocortical projections are related to the patchy cortical organizations found for spectral, temporal and binaural properties is the main question. Labeling from retrograde tracers injected into physiologically defined functional zones in cat AI/AAF will be assessed relative to functional maps. These studies will establish a functional and structural framework of signal processing in primary cortical fields. Insight into these principles is crucial for understanding the flow of information in auditory cortex, the circuits for normal auditory processing and perceptual learning, and their contributions to auditory disorders.