Early development of brain functional networks: A longitudinal EEG study

During the first years of life, functional brain networks undergo significant reconfiguration. Functional MRI (fMRI) studies have shown that maturation is driven by both the segregation of nearby functional areas (weakening of short-range functional connections) and the integration of distant regions (strengthening of long-range functional connections). While fMRI provides high spatial resolution, it does not capture rapid neural activity. Therefore, neuroimaging techniques with high temporal resolution, such as EEG, can complement fMRI data. To date, few cross-sectional studies have explored electrophysiological network development, yielding mixed results. Our study addressed these limitations by registering baseline EEG activity in a longitudinal sample of participants who were followed from 6 to 36 months of age. We computed network connectivity using different connectivity parameters (coherence, PLI, and dwPLI), in both binary and weighted networks, separately for oscillatory activity in alpha, theta, and beta frequency bands. The coherence-based connectivity networks showed the most significant age-related changes and consistent results. Specifically, we found that the small-world topology and modularity were prominent from 6 months of age, although the clustering properties and integration of the network increased with age in all frequency bands. These changes occurred in both weighted and binary networks but with opposite directions regarding network integration.