Mapping the functional connectome between grey matter and white matter

Area of Science:

• Neuroscience
• Neuroimaging
• Connectomics

Background:

• Traditionally, white matter (WM) was considered a passive conduit for neural signals.
• Emerging evidence suggests WM exhibits blood oxygen level-dependent (BOLD) signals, indicating active participation in functional networks.
• Grey matter (GM) functional networks are well-studied, but the integrated functional architecture of GM and WM remains less understood.

Purpose of the Study:

• To construct and characterize a functional connectome integrating grey matter (GM) and white matter (WM).
• To investigate the relationship between GM-WM functional architecture, neurotransmitter receptor distributions, and cognitive domains.
• To evaluate the diagnostic sensitivity of the GM-WM connectome compared to traditional GM-GM connectomes for brain disorders.

Main Methods:

• Acquisition and analysis of high-resolution 7-Tesla functional MRI (fMRI) data.
• Construction of a comprehensive GM-WM functional connectome.
• Replication of findings in an independent 3-Tesla fMRI cohort.

Main Results:

• The GM-WM functional connectome mirrors the GM's unimodal-transmodal hierarchy and is influenced by neurotransmitter receptor distributions.
• Distinct WM networks show specific connectivity profiles with GM, correlating with cognitive functions.
• Individual variations in the GM-WM connectome are linked to cognitive performance.
• The GM-WM connectome demonstrates stronger associations with brain disorders than the GM-GM connectome, suggesting higher diagnostic sensitivity.

Conclusions:

• White matter (WM) is an integral component of the brain's functional architecture, not merely a passive pathway.
• The integrated GM-WM functional connectome provides insights into hierarchical brain organization and higher-order cognition.
• The GM-WM connectome shows potential as a sensitive neuromarker for diagnosing brain disorders.