Cerebral functional connectivity periodically (de)synchronizes with anatomical constraints

TL;DR

This study reveals that resting-state functional connectivity oscillates periodically between states influenced by anatomical structure and inter-network interactions, with implications for understanding brain dynamics and mind-wandering.

Contribution

It introduces a dynamic analysis of FC-SC relationships using windowed correlation, highlighting periodic oscillations and their relation to consciousness-related networks.

Findings

FC patterns oscillate between high modularity and low modularity phases.

Default mode network contributes more to FC fluctuations than motor networks.

Optimal window width for analysis is around 20-30 TR (40-60 sec).

Abstract

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of the fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber tractography. Instead of a static analysis based on the correlation between SC and the FC averaged over the entire fMRI time series, we propose a dynamic analysis, based on the time evolution of the correlation between SC and a suitably windowed FC. Assessing the statistical significance of the time series against random phase permutations, our data show a pronounced peak of significance for time window widths around 20-30 TR (40-60 sec). Using the appropriate window width, we show that FC patterns oscillate between phases of high modularity, primarily shaped by anatomy, and phases of low modularity, primarily shaped by inter-network connectivity. Building upon recent results in dynamic FC, this emphasizes the potential role of SC as a transitory architecture between different highly connected resting state FC patterns. Finally, we show that networks implied in consciousness-related processes, such as the default mode network (DMN), contribute more to these brain-level fluctuations compared to other networks, such as the motor or somatosensory networks. This suggests that the fluctuations between FC and SC are capturing mind-wandering effects.