Converging research suggests that the resting brain operates at the cusp of dynamic instability signified by scale-free temporal correlations. We asked if the scaling properties of these correlations differ between amplitude and phase fluctuations, which may reflect different aspects of cortical functioning. Using source-reconstructed magneto-encephalographic signals, we found power-law scaling for the collective amplitude and for phase synchronization, both capturing whole-brain activity. The temporal changes of the amplitude comprise slow, persistent memory processes, whereas phase synchronization exhibits less temporally structured and more complex correlations, indicating a fast and flexible coding. This distinct temporal scaling supports the idea of different roles of amplitude and phase in cortical functioning.
@article{arxiv.1512.02574,
title = {Distinct criticality of phase and amplitude dynamics in the resting brain},
author = {Robert Ton and Gustavo Deco and Morten L Kringelbach and Mark Woolrich and Andreas Daffertshofer},
journal= {arXiv preprint arXiv:1512.02574},
year = {2015}
}