Signal propagation via cortical hierarchies

TLDR

The brain’s wiring follows a unimodal‑to‑transmodal hierarchy. The study examines how this hierarchical organization influences interregional information transmission. Hierarchical positions were derived from diffusion‑map embedding of resting‑state fMRI, structural networks were reconstructed from diffusion spectrum imaging, and topological shortest paths were analyzed to trace hierarchical motifs. The cortical hierarchy directs communication, with nodes preferentially forwarding signals to hierarchically closer regions, spanning unimodal to transmodal areas, and inducing systematic detours in attention networks, thereby shaping behaviorally relevant signal exchange.

Abstract

The wiring of the brain is organized around a putative unimodal-transmodal hierarchy. Here we investigate how this intrinsic hierarchical organization of the brain shapes the transmission of information among regions. The hierarchical positioning of individual regions was quantified by applying diffusion map embedding to resting-state functional MRI networks. Structural networks were reconstructed from diffusion spectrum imaging and topological shortest paths among all brain regions were computed. Sequences of nodes encountered along a path were then labeled by their hierarchical position, tracing out path motifs. We find that the cortical hierarchy guides communication in the network. Specifically, nodes are more likely to forward signals to nodes closer in the hierarchy and cover a range of unimodal and transmodal regions, potentially enriching or diversifying signals en route. We also find evidence of systematic detours, particularly in attention networks, where communication is rerouted. Altogether, the present work highlights how the cortical hierarchy shapes signal exchange and imparts behaviorally relevant communication patterns in brain networks.