Development of dynamic functional architecture during early infancy

Abstract Understanding the moment-to-moment dynamics of functional connectivity (FC) in the human brain during early development is crucial for uncovering neuro-mechanisms of the emerging complex cognitive functions and behaviors. Instead of calculating FC in a static perspective, we leveraged a longitudinal resting-state functional magnetic resonances imaging dataset from fifty-one typically developing infants and, for the first time, thoroughly investigated how the temporal variability of the FC architecture develops at the global (entire brain), meso- (functional system) and local (brain region) levels in the first two years of age. Our results revealed that, in such a pivotal stage, 1) the whole-brain FC dynamics is linearly increased; 2) the high-order functional systems display increased FC dynamics for both within- and between-network connections, while the primary systems show the opposite trajectories; 3) many frontal regions have increasing FC dynamics despite large heterogeneity in developmental trajectories and velocities. All these findings indicate that the brain is gradually reconfigured towards a more flexible, dynamic, and adaptive system with globally increasing but locally heterogeneous trajectories in the first two postnatal years, explaining why infants have emerging and rapidly developing high-order cognitive functions and complex behaviors.