The human brain is a dynamic modular network that can be decomposed into a set of modules and its activity changes permanently over time. At rest, several brain networks, known as Resting-State Networks (RSNs), emerge and cross-communicate even at subsecond temporal scale. Here, we seek to decipher the fast reshaping in spontaneous brain modularity and its relationship to RSNs. We use Electro/Magneto-Encephalography (EEG/MEG) to track dynamics of modular brain networks, in three independent datasets (N= 568) of healthy subjects at rest. We show the presence of striking spatiotemporal network pattern consistent over participants. We also show that some RSNs, such as default mode network and temporal network, are not necessary 'unified units' but rather can be divided into multiple sub-networks over time. Using the resting state questionnaire, our results revealed also that brain network dynamics are strongly correlated to mental imagery at rest. These findings add new perspectives to brain dynamic analysis and highlight the importance of tracking fast reconfiguration of electrophysiological networks at rest. (Desikan et al., 2006). Then, the regional time series of each subject were reconstructed using the weighted minimum norm estimate inverse solution (WMNE) for Datasets 1 and 2, and beamforming for Dataset 3. (C) Using a sliding window technique, the dynamic brain networks were computed. (D) The first step in the modularity-based algorithm is to parcellate each temporal network into communities. Then, the similarity between different temporal modular structures is assessed. (E) The similarity matrix is segmented into different communities where each one represents a modular state of specific spatial topology combining different time windows. (F) Following this, the dominant modules (common modules between different MSs) are extracted for each subject. The correspondence between these modules and the well-known RSNs is also detected. (G) The mean dwell time and fractional occupancies are calculated for the derived dominant modules.
interest (ROIs) by the means of an anatomical atlas