Trade-offs among cost, integration, and segregation in the human connectome

Abstract

The human brain structural network is thought to be shaped by the optimal trade-off between cost and efficiency. However, most studies on this problem only focused on trade-off between cost and global efficiency (i.e., integration) and overlooked the efficiency of segregated processing (i.e., segregation), which is essential for specialized information processing. Direct evidence on how trade-off among cost, integration, and segregation shapes human brain network remains lacking. Here, adopting local efficiency and modularity as segregation factors, we used multiobjective evolutionary algorithm to investigate this problem. We defined three trade-off models, which represented trade-offs between cost and integration (Dual-factor model), and trade-offs among cost, integration, and segregation (local efficiency or modularity) (Tri-factor model), respectively. Among these, synthetic networks with optimal trade-off among cost, integration, and modularity [Tri-factor model (Q)] showed the best performance. They had high recovery rate of structural connections and optimal performance in most network features, especially in segregated processing capacity and network robustness. Morphospace of this trade-off model could further capture the variation of individual behavioral/demographic characteristics in a domain-specific manner. Overall, our results highlight the importance of modularity in the formation of the human brain structural network and provide new insights into the original cost-efficiency trade-off hypothesis.

Metabolic connectivity in ageing.

“…The longer and denser the connections between nodes in a network, the higher the wiring cost of the network [25]. Activity cost is the energy consumed in neural signal activity [26]. Cost minimisation principles constrain the possible number, distance and strength of connections in a brain network to local regional nodes more likely to connect to each other, rather than regions requiring longer distance connections.…”