# The Brain’s First “Traffic Map” through Unified Structural and Functional Connectivity (USFC) Modeling

## TL;DR

This paper introduces a new brain connectivity model that combines structural and functional data to create a 'traffic map' of brain communication routes.

## Contribution

The novel contribution is the Unified Structural and Functional Connectivity (USFC) model, which reveals frequently used brain pathways and their efficiency.

## Key findings

- Subcortical, default-mode, and salience networks are heavily traversed in brain communication.
- A midline frontal-caudate-thalamus-posterior cingulate-visual cortex corridor serves as the brain's connectivity backbone.
- USFC connectome shows higher efficiency and negative associations between structural and functional connectivity in certain routes.

## Abstract

The brain’s white matter connections are thought to provide the structural basis for its functional connections between distant brain regions but how our brain selects the best structural routes for effective functional communications remains poorly understood. In this study, we propose a Unified Structural and Functional Connectivity (USFC) model and use an “economical assumption” to create the brain’s first “traffic map” reflecting how frequently each structural connection segment of the brain is used to achieve the global functional communication system. The resulting USFC map highlights regions in the subcortical, default-mode, and salience networks as the most heavily traversed nodes and a midline frontal-caudate-thalamus-posterior cingulate-visual cortex corridor as the backbone of the whole brain connectivity system. Our results further revealed a striking negative association between structural and functional connectivity strengths in routes supporting negative functional connections as well as much higher efficiency metrics in the USFC connectome when compared to structural and functional ones alone. Overall, the proposed USFC model opens up a new window for effective brain connectome modeling and provides a considerable leap forward in brain mapping efforts for a better understanding of the brain’s fundamental communication mechanisms.