The global communication pathways of the human brain transcend the cortical-subcortical-cerebellar division

TL;DR

This study maps the entire human brain's structural connectivity, revealing a hierarchical, modular network architecture with a subcortex-centered rich-club that integrates cortex, subcortex, and cerebellum, challenging cortico-centric views.

Contribution

It provides the first comprehensive structural connectome including cortex, subcortex, and cerebellum, highlighting a subcortex-dominated rich-club that centralizes brain communication pathways.

Findings

The brain's network is modular and hierarchical.

The rich-club is subcortex-dominated and composed of diverse subcortical hubs.

Cross-modular pathways are centralized through highly connected hub regions.

Abstract

Understanding how cortex, subcortex and cerebellum integrate is a major challenge for neuroscience, however, studies of the brain's structural connectivity have mostly focused on cortico-cortical links. Here, we used diffusion imaging to construct the structural connectome of the entire human brain including 360 cortical, 233 subcortical, and 125 cerebellar regions of interest (ROIs). We found that the brain forms a modular and hierarchical network architecture, organized into modules of mixed cortical, subcortical and/or cerebellar regions, and whose cross-modular pathways are centralized through highly connected hub ROIs (a `rich-club'). This global rich-club is subcortically dominated and, surprisingly, composed of hub ROIs from all subcortical structures rather than one region like the thalamus, centralizing the communication pathways. This study improves our understanding of the human brain's organization. It provides structural evidence to question the prevalent cortico-centric notion by revealing a connectome centered at the subcortex but made of transversal pathways.