Thalamocortical Circuits and Auditory Neocortical Maps

描述（由申请人提供）：听力和语言理解的基础在于首先在基底膜水平上看到的频率图。这张图保存在整个上升的听觉系统中，直到并包括听觉新皮层。虽然我们知道听觉脑干的结构适应是频率图的基础，但对于这些频率图在听觉丘脑和人工智能中的解剖学基础知之甚少。最近，我们证实了兔上腺病毒中存在两个功能不同的区域；侧部（LV）和卵母部（OV）。与其他物种相比，这些区域可以很容易地在兔的免疫细胞化学和解剖学上区分，使该物种成为研究听觉神经系统结构/功能关系的优秀模型。常规尼氏染色可见兔上腺腺的层状结构。测绘研究表明，层状层位于MGV频率图之下。脑板内的MGV神经元焦点群以斑块或群集的方式向人工智能投射。解剖学和电生理学的综合研究表明，这些丘脑纹层似乎支配着听觉皮层编码频率和双耳性的不同功能区域。这些数据支持连接听觉丘脑和新皮层的多种不同通道的存在。我们已经开发了一个模型，该模型解释了LV的斑块TC投影如何解释AI中的不连续（例如，双耳性）和连续（例如，频率）地图。该模型将在麻醉的NZW家兔中使用顺行标记和电生理相结合的方法进行测试。在具体目标1中，将使用顺行标记和电生理映射的组合来比较从OV和LV投射到AI的神经回路。在特定目标2中，双顺行标记和制图研究将用于确定不同层如何投射到AI并有助于皮质图。在特定目标3中，我们将应用与特定目标2中类似的技术，从单个左室板的两个生理不同位置比较丘脑皮质投影模式和功能地形。这些研究有可能揭示人工智能功能图谱的结构基础，并对理解正常、衰老和受损人耳的听觉皮层可塑性具有重要意义。

DESCRIPTION (provided by applicant): The basis of hearing and speech comprehension lies in the frequency map first seen at the level of the basilar membrane. This map is preserved throughout the ascending auditory system up to and including the auditory neocortex. Although the structural adaptations in the auditory brainstem that underlie frequency maps are known, very little is understood regarding the anatomical substrate for these maps in the auditory thalamus and AI. Recently, we confirmed the existence of two functionally distinct regions in the rabbit MGV; the pars lateralis (LV) and pars ovoidea (OV). In contrast to other species, these regions can be easily distinguished immunocytochemically and anatomically in the rabbit, making this species an excellent model for studying structural/functional relationships in the auditory nervous system. A laminar architecture in the rabbit MGV is visible with routine Nissl stains. Mapping studies have revealed that the laminae underlie the MGV frequency map. Focal groups of MGV neurons within a laminae project in a patchy or clustered manner to AI. Combined anatomical and electrophysiological studies indicate that these thalamic laminae appear to innervate separate functional regions coding frequency and binaurality in the auditory cortex. These data support the existence of multiple divergent channels linking the auditory thalamus and neocortex. We have developed a model that explains how patchy TC projections from the LV can account for discontinuous (e.g., binaurality), as well as continuous (e.g., frequency), maps in AI. This model will be tested using a combination of anterograde labeling and electrophysiological methods in anesthetized NZW rabbits. In specific aim 1, a combination of anterograde labeling and electrophysiological mapping will be used to compare the neural circuits that project from the OV and LV to AI. In specific aim 2, double anterograde labeling and mapping studies will be used to determine how different laminae project to AI and contribute to cortical maps. In specific aim 3, we will apply techniques similar to those in specific aim 2 to compare thalamocortical projection patterns and functional topography from two physiologically distinct locations in a single LV lamina. These studies have the potential for revealing the structural basis of functional maps in AI and have important implications for understanding auditory cortical plasticity in normal, aging and impaired human ears.