THE DEVELOPMENT & STRUCTURE OF VISUAL CORTICAL MAPS

发展历程

• 批准号: 6384808
• 负责人: GEOFFREY J GOODHILL
• 金额: $ 13.16万
• 依托单位: GEORGETOWN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-30 至 2003-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6384808
• 关键词: computational neuroscience; computer program /software; developmental neurobiology; mathematical model; model design /development; neuroanatomy; synapses; visual cortex

Two key questions for understanding the visual system are, how is information about the world represented in the cortex, and how are these representations formed during development. The best studied cortical areas in this regard are V1 and V2, where features of the visual scene such as position, orientation, direction and spatial frequency are represented in maps with complex local and global structure. Understanding how these maps develop, and what principles underlie their final structure, is an important step in answering the above questions. The relative contribution of genetic versus epigenetic (particularly activity-dependent) mechanisms in determining visual cortical structure is still a subject of intense debate. This debate impacts directly on the design of effective therapies for treating the effects of early abnormal visual experience, such as strabismus. Visual cortical map structure arises from activity-dependent learning rules that attempt to represent highly correlated input features close together, acting in conjunction with genetically determined constraints such as the shape of the target area. Both the local and global structure of maps in V1 and V2 can be accounted for in terms of the interaction between the correlational structure of afferent activity, patterns of intracortical connections, and the shape of the cortical target region. Changes in map structure due to abnormal rearing paradigms such as monocular deprivation and strabismus follow naturally from the same rules. The hypothesis will be tested using computational models suited to exploring questions of large scale map structure. These models will be applied to low dimensional feature spaces representing position, orientation, ocular dominance, direction, spatial frequency, disparity, and color. Several types of parameter variation will be investigated, including variations in the statistical structure of afferent activity, variations in the pattern of intracortical connections, variations in the way similarity between input features is measured, and variations in the shape of the target region. At each stage, simulation results will be directly compared to experimental data using a range of quantitative techniques. The analysis and simulation of these computational models will lead to experimentally testable predictions concerning the parameters underlying cortical map formation and the effects of visual experience on cortical map structure.

理解视觉系统的两个关键问题是，关于世界的信息如何在皮层中表示，以及这些表示在发育过程中如何形成。 在这方面研究最好的皮质区域是 V1 和 V2，其中视觉场景的特征（例如位置、方向、方向和空间频率）以具有复杂的局部和全局结构的图表示。 了解这些地图是如何发展的，以及它们最终结构的原理是什么，是回答上述问题的重要一步。 遗传与表观遗传（尤其是活动依赖性）机制在决定视觉皮层结构中的相对贡献仍然是激烈争论的主题。 这场争论直接影响了治疗斜视等早期异常视觉体验影响的有效疗法的设计。视觉皮层图结构源于依赖于活动的学习规则，这些规则试图将高度相关的输入特征紧密地表示在一起，并与遗传确定的约束（例如目标区域的形状）结合起来。 V1 和 V2 中图的局部和全局结构都可以根据传入活动的相关结构、皮质内连接模式和皮质目标区域的形状之间的相互作用来解释。 由于单眼剥夺和斜视等异常饲养范式导致的地图结构的变化自然遵循相同的规则。该假设将使用适合探索大比例地图结构问题的计算模型进行测试。 这些模型将应用于表示位置、方向、视觉优势、方向、空间频率、视差和颜色的低维特征空间。 将研究几种类型的参数变化，包括传入活动统计结构的变化、皮质内连接模式的变化、测量输入特征之间相似性的方式的变化以及目标区域形状的变化。 在每个阶段，模拟结果将使用一系列定量技术直接与实验数据进行比较。 这些计算模型的分析和模拟将导致关于皮层图形成的参数以及视觉体验对皮层图结构的影响的可实验测试的预测。