Functional Hypergraph Uncovers Novel Covariant Structures over Neurodevelopment

TL;DR

This study introduces a hypergraph approach to analyze adolescent brain development, revealing distinct sub-network classes and their evolution, providing a new perspective on functional brain network topology during neurodevelopment.

Contribution

The paper applies a novel hypergraph method to resting-state fMRI data, uncovering three classes of sub-networks and their developmental trajectories, which differ from traditional network analyses.

Findings

Identified three classes of hyperedges: clusters, bridges, and stars.

Cluster hyperedges align with known functional modules.

Developmental changes are most prominent in core network hyperedges.

Abstract

Brain development during adolescence is marked by substantial changes in brain structure and function, leading to a stable network topology in adulthood. However, most prior work has examined the data through the lens of brain areas connected to one another in large-scale functional networks. Here, we apply a recently-developed hypergraph approach that treats network connections (edges) rather than brain regions as the unit of interest, allowing us to describe functional network topology from a fundamentally different perspective. Capitalizing on a sample of 780 youth imaged as part of the Philadelphia Neurodevelopmental Cohort, this hypergraph representation of resting-state functional MRI data reveals three distinct classes of sub-networks (hyperedges): clusters, bridges, and stars, which represent spatially distributed, bipartite, and focal architectures, respectively. Cluster hyperedges show a strong resemblance to the functional modules of the brain including somatomotor, visual, default mode, and salience systems. In contrast, star hyperedges represent highly localized subnetworks centered on a small set of regions, and are distributed across the entire cortex. Finally, bridge hyperedges link clusters and stars in a core-periphery organization. Notably, developmental changes within hyperedges are ordered in a similar core-periphery fashion, with the greatest developmental effects occurring in networked hyperedges within the functional core. Taken together, these results emphasize that the network organization of human brain emerges across multiple scales and evolves substantially through the adolescent period.