Theoretical studies of visual cortex

描述（由申请人提供）：本提案的长期目标是了解初级视觉皮层的接受区和功能图在发育过程中是如何连接的。多年来，人们提出了许多理论模型来解释视觉皮层柱状组织的起源。尽管许多实验和理论的进步，关键问题仍然开放的功能和来源的柱状系统。其中包括功能图的实际起源，它们之间的相互关系，最重要的是，它们对正常视觉处理的意义。我们的工作假设是，丘脑和皮层之间的“统计连接”为柱状图的形成提供了一个初始蓝图，随后在关键时期由活动依赖过程维持和修改柱状图。我们建议通过解决以下目标来详细阐述、概括和批判性地测试这一想法。目标1：我们将量化预测图的各种特征，它们之间的相互关系，并将结果与实验数据进行比较。我们还将研究视网膜异位图的局部各向异性如何与其他特征图的结构相关。目的2：我们将研究神经元选择性如何依赖于细胞在功能图谱上的位置。目标3：我们将研究现有的依赖活动的发展模型如何运作，以维持或修改由统计连通性建立的初始结构。目的4：我们将测试一个新的假设，关于形成的眼优势柱，克服了对侧输入的初始优势。提出的工作将批判性地评估统计连通性理论在解释无数已发表的实验结果时的优点和缺点，并产生新的预测。如果这一理论经得起时间的考验，它可能会为皮层结构的起源提供一个统一的解释，并阐明在发育过程中哪些特征可能会被活动依赖机制所改变。总之，这些研究可能会从根本上改变我们看待早期视觉皮层中感受野和图的连接方式，以及皮层图对视觉的功能意义。

DESCRIPTION (provided by applicant): The long term goal of this proposal is to understand how receptive fields and functional maps in the primary visual cortex are wired during development. Over the years, a number of theoretical models have been put forward to explain the origin of the columnar organization of visual cortex. Despite numerous experimental and theoretical advances, key questions remain open about the function and source of columnar systems. These include the actual origin of functional maps, their mutual relationships and, most importantly, their significance for normal visual processing. Our working hypothesis is that 'statistical connectivity' between the thalamus and the cortex provides an initial blueprint for the formation columnar maps that is subsequently maintained, and modified, by activity- dependent processes during the critical period. We propose to elaborate, generalize, and critically test this idea by addressing the following aims. Aim 1: We will quantify various features of the predicted maps, their mutual relationships, and compare the results to experimental data. We will also investigate how the local anisotropy of the retinotopic map is related to the structure of other feature maps. Aim 2: We will investigate how neuronal selectivity depends on the location of the cell across the functional maps. Aim 3: We will study how existing activity-dependent developmental models could operate to maintain, or modify, the initial structures set up by statistical connectivity. Aim 4: We will test a novel hypothesis regarding the formation of ocular dominance columns that overcomes the initial dominance by contralateral input. The proposed work will critically evaluate the merits and weaknesses of statistical connectivity theory in explaining a myriad of published experimental findings and generate novel predictions. If the theory stands up to the test of time, it could potentially provide a unified explanation for the origin of the cortical architecture and clarify which of its features are expected to be modified by activity-dependent mechanisms during development. Altogether, these studies could radically alter the way we look at the wiring of receptive fields and maps in early visual cortex and the functional significance of cortical maps for vision.