Brain rhythms define distinct interaction networks with differential dependence on anatomy

Cognitive functions are subserved by rhythmic neuronal synchronization across widely distributed brain areas. In 105 area pairs, we investigated functional connectivity (FC) through coherence, power correlation, and Granger causality (GC) in the theta, beta, high-beta, and gamma rhythms. Between rhythms, spatial FC patterns were largely independent. Thus, the rhythms defined distinct interaction networks. Importantly, networks of coherence and GC were not explained by the spatial distributions of the strengths of the rhythms. Those networks, particularly the GC networks, contained clear modules, with typically one dominant rhythm per module. To understand how this distinctiveness and modularity arises on a common anatomical backbone, we correlated, across 91 area pairs, the metrics of functional interaction with those of anatomical projection strength. Anatomy was primarily related to coherence and GC, with the largest effect sizes for GC. The correlation differed markedly between rhythms, being less pronounced for the beta and strongest for the gamma rhythm.

Automated summary

Cognitive functions are supported by rhythmic neuronal synchronization across various brain areas, and the distinct interaction networks defined by different rhythms were not explained by the spatial distributions of the strengths of the rhythms. The networks, especially the Granger causality networks, exhibited clear modular structures with one dominant rhythm per module. Anatomy was found to be primarily related to coherence and Granger causality, with the largest effect sizes for Granger causality, and the correlation between functional interaction metrics and anatomical projection strength varied between rhythms, being less pronounced for beta and strongest for gamma rhythm.