Time-resolved structure-function coupling in brain networks

Abstract

The relationship between structural and functional connectivity in the brain is a key question in systems neuroscience. Modern accounts assume a single global structure-function relationship that persists over time. Here we show that structure-function coupling is dynamic and regionally heterogeneous. We use a temporal unwrapping procedure to identify moment-to-moment co-fluctuations in neural activity, and reconstruct time-resolved structure-function coupling patterns. We find that patterns of dynamic structure-function coupling are highly organized across the cortex. These patterns reflect cortical hierarchies, with stable coupling in unimodal and transmodal cortex, and dynamic coupling in intermediate regions, particularly in insular cortex (salience network) and frontal eye fields (dorsal attention network). Finally, we show that the variability of structure-function coupling is shaped by the distribution of connection lengths. The time-varying coupling of structural and functional connectivity points towards an informative feature of the brain that may reflect how cognitive functions are flexibly deployed and implemented.

Assortative mixing in micro-architecturally annotated brain connectomes

“…Indeed, the longest connections, in structural (diffusion and tract-tracing) and functional connectomes are significantly disassortative, meaning that they are more likely to connect dissimilar regions than expected from the brain's spatial embedding. This is in line with the notion that greater prevalence of short-range connections [27,37,46,61,74], which presumably entail lower material and metabolic cost [17], is counterbalanced by a small number of high-cost, high-benefit long-range connections that support communication between regions with diverse functions [10,53]. Previous studies have found that long-range connections, which are heterogeneously distributed along microarchitectural and cognitive hierarchies [79,106], help to shorten communication pathways [94], and bridge specialized modules [11].…”

Multi-policy models of interregional communication in the human connectome

“…Because the summation across time of co-fluctuation matrices is precisely the static FC matrix, and because the co-fluctuation cluster centroids are predicted by different communication policies, we might speculate that the static FC matrix is, in fact, the superposition of many distinct communication events, each of which was driven by a different communication policy [34]. The topic of time-varying structure-function coupling is, in general, understudied and has not been fully explored using communication models (but see [28, 54]).…”

“…That is, it is assumed that every pair of regions communicates using an identical policy. Here, at least, some progress has been made, as several recent studies have begun to assess the regional heterogeneity in optimal communication policies [26][27][28]. Nonetheless, modeling communication policies locally rather than globally is uncommon.…”

“…Finally, the incorporation of multiple competing policies within the same model has proven elusive. At present, the “state-of-the-art” is to generate non-interacting communication measures corresponding to different policies and combine them as explanatory terms in a multi-linear model [25, 28].…”

Communication dynamics in the human connectome shape the cortex-wide propagation of direct electrical stimulation

“…Network communication models provide tractable interpretations of the interplay between structural connectivity and inter-areal interactions, and can thus be used to form and test hypotheses about the relationship between brain structure and function. An emerging body of evidence indicates that these models can explain inter-individual variation in cognitive [18,19] and clinical [20][21][22][23][24] variables, as well as various aspects of functional and effective connectivity derived from blood-level-oxygen dependent (BOLD) fMRI time courses [16,[25][26][27][28][29][30][31][32][33][34].…”