Spatial patterns of the fluctuations shown by the different areas of the brain at rest are well known. However, recent studies indicate that this activity is not stationary, but shows a complex dynamics over time. The study of spontaneous brain activity has focused on the characterization of these functional interactions variables over time.

Using techniques that measure brain activity according to oxygen consumption (BOLD fMRI), Adrián Ponce Álvarez and Gustavo Deco (ICREA), researcher and director of the Center for Brain and Cognition (CBC) of the  Department of Information and Communications Technology (DTIC) at UPF, respectively, together with a team of researchers from the USA, Italy, the UK and Switzerland have shown that the synchrony of the global phase evolves into a characteristic ultra-slow time scale (<0.01 Hz), and that the temporal variations observed reflect the transient formation-dissolution of multiple communities of synchronized brain regions. The work has been published in the journal PLOS Computational Biology.

Observation has shown that communities of synchronized brain regions reappear intermittently over time. The authors have shown that the communities that are synchronized are the ones related to networks whose function corresponds to the resting state (RSN, resting-state networks) which are known to be engaged in sensory-motor and cognitive functions and include motor, visual, hearing, cognitive control, self-referential networks, and combinations of these and other RSNs.

As Ponce and Deco comment, "this study shows how the synchrony of different brain regions undergoes slow fluctuations of a global nature reflecting the association-dissociation of functional groups of synchronized neural networks".

The modelling of the phase oscillators in the brain's anatomical connectivity, estimated using diffusion imaging human data, approximates the temporal and spatial patterns of the empirical data and reveals that multiple clusters that transiently synchronize and desynchronize emerge from the complex topology of the brain's anatomical connections, provided that oscillators are heterogeneous.

"Our results suggest that the brain during the resting state is constantly exploring its dynamics to have information about its functional state", the authors comment. 

Reference work:

Adrián Ponce-Álvarez, Gustavo Deco, Patric Hagmann, Gian Luca Romani, Dante Mantini and Maurizio Corbetta (2015), " Resting-State Temporal Synchronization Networks Emerge From Connectivity Topology and Heterogeneity" ,  PLOS Computational Biology, doi: 10.1371/journal.pcbi.1004100.