Multi-timescale cortical functional connectivity across brain states

The synchronization of the phase of neuronal oscillations and the correlated fluctuations in the envelopes of neuronal signals are two prominent coupling modes that govern the brain dynamics. They mediate in an efficient and selective manner the communication in networks of cortical and subcortical areas to facilitate sensory processing, behavior, and perception. However, it is not clear yet if and how these two types of intrinsic coupling modes (ICMs) interact with each other. Here we investigate the relation between both coupling modes across different brain states. In accordance with our previous work [Stitt et al, Sci Rep 7, 8797, 2017], we recorded resting state activity from the ferret (Mustela furo) occipital, parietal, and temporal cortical regions with chronically implanted micro-electrocorticographic (μECoG) arrays and classified the animals’ state as awake, slow wave sleep or REM sleep. We used mutual information to quantify the statistical interdependency between phase and envelope ICMs. We found that the amount of information that is shared by both types of ICMs over the recording time is relatively high, especially across occipital regions, and dependent on the frequency range analyzed. Additionally, the connectivity matrices are not constant but, as expected, reshape continuously over time. We used this result to explore the re-classification of the brain states based on the coupling modes. These results contribute to a better understanding of the role different ICMs in brain network dynamics. Furthermore, they may enable new insights into alterations of functional connectivity on different time scales in brain disorders.