Cortical feedback microcircuits in the visual system of the mouse.

小鼠视觉系统中的皮质反馈微电路。

• 批准号: 203702-2013
• 负责人: Boire, Denis
• 金额: $ 1.82万
• 依托单位: Université du Québec à Trois-Rivières
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=593854
• 关键词: Cortical; feedback; microcircuits; visual; system

Integrated perception of the outside world emerges from the processing of sensory information in multiple areas of the cerebral cortex. It is generally believed that the multiple cortical areas are reciprocally interconnected by an intricate network of feedforward and feedback connections. Forward connections provide information from lower to higher areas for further (bottom-up) processing. Feedback connections send information from higher areas and modulate lower areas activity (top-down). From these types of connections a general hierarchical model of cortical processing has been proposed and has been applied to primates, cats and rodents. These types of cortical connections are defined by the distribution of the cells of origin and their terminal axons in the 6 layers of the cerebral cortex. This gross pattern of laminar distribution of axonal terminals is the result of the sum of a host of single axons. Observations of single axons show a variety of termination patterns some of which are common to both forward and backward connections. There is yet no in depth understanding of the microcircuits that constitute these cortical macrocircuits. The classical model of hierarchical cortical networks has recently been challenged and the cerebral cortex is now more perceived as a distributed rather than a hierarchical network. It is increasingly evident that a dichotomous classification of cortical connections cannot account for the broad spectrum of connection types. At a local level, there is clear evidence for cortical microcircuits that reflect the long range target of axons to cortical and subcortical structures. The objective of the present proposal is a study of the fine structure of corticocortical connections at the single axon level in order to define the building blocs of these connection patterns. In doing this, we will have the basis to devise a novel classification of cortical connection that will account for their diversity. We will also provide basic knowledge of how these long range cortical connections are related to local microcircuits.

对外界的综合感知是大脑皮层多个区域对感觉信息的处理产生的。人们普遍认为，多个皮质区域通过复杂的前馈和反馈连接网络相互连接。前向连接提供从较低区域到较高区域的信息以进行进一步（自下而上）处理。反馈连接从较高区域发送信息并调节较低区域的活动（自上而下）。根据这些类型的连接，提出了皮质处理的通用分层模型，并将其应用于灵长类动物、猫和啮齿类动物。这些类型的皮质连接由大脑皮层 6 层中的起源细胞及其末端轴突的分布来定义。轴突末端层状分布的总体模式是许多单个轴突总和的结果。对单个轴突的观察显示了多种终止模式，其中一些对于前向和后向连接是常见的。目前对构成这些皮质宏电路的微电路还没有深入的了解。分层皮质网络的经典模型最近受到了挑战，大脑皮层现在更多地被视为分布式网络而不是分层网络。越来越明显的是，皮质连接的二分分类不能解释广泛的连接类型。在局部水平上，有明确的证据表明皮质微电路反映了轴突对皮质和皮质下结构的远距离目标。本提案的目的是研究单轴突水平上皮质连接的精细结构，以便定义这些连接模式的构建块。在此过程中，我们将有基础来设计一种新颖的皮质连接分类，以解释其多样性。我们还将提供有关这些长距离皮层连接如何与局部微电路相关的基本知识。