Hierarchical counterstream via feedforward and feedback interactions is a major organizing principle of the cerebral cortex. The counterstream, as a topological feature of the network of cortical areas, is captured by the convergence and divergence of paths through directed links. So defined, the convergence degree (CD) reveals the reciprocal nature of forward and backward connections, and also hierarchically relevant integrative properties of areas through their inward and outward connections. We asked if topology shapes large-scale cortical functioning by studying the role of CD in network resilience and Granger causal coupling in a model of hierarchical network dynamics. Our results indicate that topological synchronizability is highly vulnerable to attacking edges based on CD, while global network efficiency depends mostly on edge betweenness, a measure of the connectedness of a link. Furthermore, similar to anatomical hierarchy determined by the laminar distribution of connections, CD highly correlated with causal coupling in feedforward gamma, and feedback alpha-beta band synchronizations in a well-studied subnetwork, consisting primarily of lower visual cortical areas. In contrast, causal coupling did not correlate with edge betweenness. Considering the entire network, the CD-based hierarchy correlated well with both the anatomical and functional hierarchy for low-level areas that are far apart in the hierarchy. Conversely, in a large part of the anatomical network where hierarchical distances are small between the areas, the correlations were not significant. These findings suggest that CD-based and functional hierarchies are interrelated in low-level processing in the visual cortex. Our results are consistent with the idea that the interplay of multiple hierarchical features forms the basis of flexible functional cortical interactions.

中文翻译：

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网络路径融合塑造了视觉皮层中的低级处理

通过前馈和反馈相互作用的分层逆流是大脑皮质的主要组织原理。作为皮质区域网络的拓扑特征的逆流通过定向链接的路径的收敛和发散来捕获。如此定义的收敛度（CD）揭示了向前和向后连接的倒数本质，并通过区域的向内和向外连接揭示了区域的层次相关的集成特性。我们通过在分层网络动力学模型中研究CD在网络弹性和Granger因果耦合中的作用，询问拓扑结构是否会影响大规模皮质功能。我们的结果表明，拓扑可同步性极易受到基于CD攻击边缘的攻击，而全局网络效率主要取决于边缘之间的间隔，链接的连通性的度量。此外，类似于由连接的层状分布确定的解剖层​​次，CD与前馈伽马中的因果耦合高度相关，并且在经过充分研究的子网中（主要由较低的视觉皮层区域组成）反馈α-β带同步。相反，因果耦合与边之间的关系不相关。考虑到整个网络，基于CD的层次结构与层次结构中相距较远的低层区域的解剖结构和功能层次结构相关性很好。相反，在解剖网络的大部分区域之间的层次距离较小的情况下，相关性并不显着。这些发现表明，在视觉皮层的低级处理中，基于CD的层次结构和功能层次结构是相互关联的。我们的结果与以下想法一致：多个层次特征的相互作用形成了灵活的功能性皮层相互作用的基础。