FUNCTIONAL ORGANIZATION OF THE AUDITORY CORTEX

我们提出灵长类听觉皮层包括一个由3个类似初级区域组成的核心区域，周围是一个包含7或8个区域的带状区域，以及一个至少有两个细分的平行带状区域。每个区域代表一个连续的处理级别，每个区域内的细分由并行输入激活。所提议的组织的某些方面是完善的，而其他方面则不是。因此，一个目标是通过检查内侧带区域的功能组织来评估和扩展当前的理论，内侧带区域位于听觉核心和岛叶/顶叶皮层之间的中间位置，尚未被详细研究。内侧带场的解剖和生理特性的表征对于更全面地了解听觉皮层组织，以及建立皮层中听觉和躯体感觉系统之间的关系具有重要意义。在这些实验中，将使用多单元记录来指导示踪剂注射，并确定这些场内神经元簇的频率响应区域。通过对连接、结构和生理学的分析，我们将评估和扩展内侧带区组织的建议，并确定它们与听觉相关的皮层和皮层下区域的关系。因此，虽然这些研究的重点将放在内侧带区域，但实验设计包括分析皮层、丘脑和中脑的所有听觉处理水平。一个相关的问题是猴子听觉皮层组织的基本原理在多大程度上可以推广到人类。作为第二个目标，我们将比较非人类灵长类动物和人类听觉皮层的结构特征。对细胞结构、骨髓结构和乙酰胆碱酯酶、细胞色素氧化酶、小白蛋白、钙结合蛋白、SMI-32和CAT-301分布的分析将结合起来，表征和比较猴子、猿和人类听觉皮层的核心、带和旁带场的结构。我们期望在物种之间找到相似之处，但与功能专门化有关的重要差异可能存在。随着对听觉皮层基本功能组织的了解越来越多，研究病理对皮层组织和恢复能力的影响成为可能。

We have proposed that the primate auditory cortex includes a core region of three primary-like areas, surrounded by a belt region containing seven or eight areas, and a parabelt region that has at least two subdivisions. Each region represents a successive level of processing, and subdivisions within each region are activated by parallel inputs. Some aspects of the proposed organization are well-established, while others are not. Thus, one goal is to evaluate and extend the current theory by examining functional organization in the medial belt region, which occupies an intermediate position between the auditory core and insular/parietal cortex, and has not been studied in detail. Characterization of the anatomical and physiological properties of the medial belt fields is important for a more complete understanding of auditory cortical organization, and also in the establishment of the relationship between auditory and somatic sensory systems in cortex. In these experiments, multiunit recordings will be used to guide tracer injections and determine the frequency response area of neuronal clusters within these fields. Through analysis of connections, architecture, and physiology we will evaluate and extend proposals of the organization of medial belt fields, and determine their relationship to auditory-related cortical and subcortical areas. Thus, although the focus of these studies will be on the medial belt region, the experimental design involves analysis at all levels of auditory processing in the cortex, thalamus, and midbrain. A related issue concerns the extent to which the basic principles of auditory cortical organization in monkeys can be generalized to humans. As a second aim, we will compare architectonic features of auditory cortex in non-human primates and humans. Analyses of cytoarchitecture, myeloarchitecture, and the distribution of acetylcholinesterase, cytochrome oxidase, parvalbumin, calbindin, SMI-32, and CAT-301 will be combined to characterize and compare the architecture of core, belt, and parabelt fields in the auditory cortex of monkeys, apes, and humans. We expect to find similarities across species, but important differences may exist that relate to functional specializations. As more is learned concerning the basic functional organization of auditory cortex, it becomes possible to study the effects of pathology on cortical organization and the capacity for recovery.