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质中的接受场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皮层柱状组织的起源。尽管在实验和理论上取得了许多进展，但关于柱状系统的功能和来源的关键问题仍然悬而未决。这些包括功能图的实际起源，它们的相互关系，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，丘脑和皮质之间的统计连接为形成柱状图提供了初步蓝图，随后在关键时期通过依赖活动的过程来维护和修改该图。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：我们将对预测地图的各种特征及其相互关系进行量化，并将结果与实验数据进行比较。我们还将研究视网膜定位图的局部各向异性如何与其他特征图的结构相关联。目标2：我们将研究神经元的选择性如何依赖于细胞在功能图上的位置。目标3：我们将研究现有的依赖活动的发育模型如何维持或修改由统计连通性建立的初始结构。目的4：我们将检验一种新的假说，即眼优势柱的形成可以通过对侧输入克服最初的优势。这项拟议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和产生新预测方面的优缺点。如果这一理论经得起时间的考验，它可能会为大脑皮层结构的起源提供一个统一的解释，并澄清它的哪些特征有望在发育过程中被活动依赖机制改变。总而言之，这些研究可能会从根本上改变我们看待早期视觉皮质中感受野和地图连接的方式，以及皮质地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.