Abstract

Resting-state brain activity exhibits two distinct modes of coupling between brain regions, i.e. coupling between amplitude envelopes and coupling between phases of neuronal oscillations. RSNs (Resting-State Networks) of coupling between amplitude envelopes have been identified with fMRI and MEG , and supposedly reflect sets of regions whose excitability is co-modulated. However, not much is known about RSNs of phase-coupling, which might reflect sets of regions between which communication is regulated. In this study, we identified phase-coupling RSNs from intra-cranial EEG recordings of 64 subjects, at 18 frequency levels from 3-320 Hz. We measured activity from neuronal populations using white-matter referencing and used community detection methods from graph theory to identify RSNs from whole-brain networks of phase-coupling. First, we found evidence that phase-coupling RSNs have a multi-scale organisation such that they can be recovered at multiple levels of spatial detail. Next, we found that phase-coupling RSNs at different frequency levels could be grouped such that each group corresponded to well-known frequency bands (delta, theta/alpha, beta, gamma etc.). Finally, we found that phase-coupling RSNs up to 80 Hz comprise spatially contiguous regions that are known to be functionally related. These findings support the functional relevance of resting-state dynamics and provide new information on those sets of regions that are functionally interacting at rest, over and above those revealed by fMRI RSNs.