Weak Higher-Order Interactions in Macroscopic Functional Networks of the Resting Brain

Area of Science:

• Neuroscience
• Complex Systems Analysis
• Network Science

Background:

• Brain region interactions are typically studied using functional connectivity (FC), which measures pairwise correlations.
• Higher-order interactions (HOIs) beyond pairwise correlations are crucial for complex systems but their role in the brain is unclear.

Purpose of the Study:

• To investigate the existence and impact of HOIs in macroscopic brain functional networks.
• To determine if HOIs influence brain activity and to explore potential underlying mechanisms.

Main Methods:

• Analysis of blood oxygenation-level-dependent (BOLD) signals from six macroscopic brain networks in 100 resting-state human subjects.
• Examination of binarized BOLD signals to quantify HOIs across various network properties.
• Network modeling to explore dynamical mechanisms potentially underlying HOI levels.

Main Results:

• HOIs within and across macroscopic brain networks were found to be consistently weak.
• HOI weakness persisted irrespective of network size, topology, spatial proximity, scale, or global signal regression.
• Network model simulations indicated weak HOIs near a linear fluctuation regime, mirroring empirical findings.

Conclusions:

• Weak HOIs suggest that pairwise interactions dominate macroscopic brain network activity.
• The findings validate the widespread use of pairwise-based FC approaches for analyzing brain networks.
• This study reveals a potentially simple organizational principle in the brain's macroscopic functional systems.