An edge-centric perspective on the human connectome: link communities in the brain

Abstract

Brain function depends on efficient processing and integration of information within a complex network of neural interactions, known as the connectome. An important aspect of connectome architecture is the existence of community structure, providing an anatomical basis for the occurrence of functional specialization. Typically, communities are defined as groups of densely connected network nodes, representing clusters of brain regions. Looking at the connectome from a different perspective, instead focusing on the interconnecting links or edges, we find that the white matter pathways between brain regions also exhibit community structure. Eleven link communities were identified: five spanning through the midline fissure, three through the left hemisphere and three through the right hemisphere. We show that these link communities are consistently identifiable and investigate the network characteristics of their underlying white matter pathways. Furthermore, examination of the relationship between link communities and brain regions revealed that the majority of brain regions participate in multiple link communities. In particular, the highly connected and central hub regions showed a rich level of community participation, supporting the notion that these hubs play a pivotal role as confluence zones in which neural information from different domains merges.

Complex network theory and the brain

“…de Reus et al [31] investigate how complex network theory can be applied to the analysis of anatomical networks from a link-based perspective, instead of the traditional view of node-based analysis. The authors analyse how links between brain regions are organized in communities and evaluate their robustness introducing a new class of edge removal metrics.…”

Simulated rich club lesioning in brain networks: a scaffold for communication and integration?

“…The approach of Irimia and Van Horn to quantify how lesioning an individual connection affects the global network structure is an elegant way to shift focus from nodes to edges and provides insight in the role or importance of the disrupted connection (de Reus et al, in press). …”

Midsagittal Brain Variation among Non-Human Primates: Insights into Evolutionary Expansion of the Human Precuneus

“…Functional studies have revealed that the precuneus is involved in a variety of functions associated with self-perception and visual imagery [Lou et al, 2004; Land, 2014], processing of spatial working memory [Wallentin et al, 2006, 2008], and memory retrieval (recognition of familiar faces [Gobbini and Haxby, 2007; Lee et al, 2013]; episodic memory [Vannini et al, 2011]; recognition memory [Hassabis and Maguire, 2009] autobiographical memory [Freton et al, 2014]). Moreover, the precuneus is a functional core of the Default Mode Network, a set of interconnected cortical areas that is active at rest [Raichle et al, 2001; Tomasi and Volkow, 2010; Utevsky et al, 2014], and it is a crucial hub of large-scale brain connectivity [Hagmann et al, 2008; Li et al, 2013; Reus et al, 2014]. Therefore, the precuneus is a region that is both structurally and functionally central for integrating multiple neural systems, and is comprised of different sub-regions involved in distinct cognitive functions [Margulies et al, 2009; Zang and Li 2012].…”