Spatiotemporal dynamics of EEG microstate networks over the first two years of life: A multi-cohort longitudinal study

Abstract

The first two years of life are marked by rapid development of large-scale brain networks that support emerging cognition and behavior. Magnetic-resonance approaches have revealed much about largescale networks in sleep, but very little is known about functional network dynamics in awake, behaving infants during this period of substantial development. Microstates are brief instances of distinct spatial topographies of largescale neural activity measured with electroencephalography (EEG) that offer a novel approach to studying whole-brain network dynamics at sub-second scale in awake infants by capturing their temporally coherent brain activity. While emerging literature is leveraging microstate dynamics in adults to understand mature largescale network function, developmental trajectories during networks rapid construction in infancy remain uncharacterized. In this study, we leveraged longitudinal resting-state EEG data from 854 infants across two geoculturally diverse cohorts to explore largescale network development through EEG microstates over the first two years of life. We provide evidence for conserved emergence of various network configurations (microstate classes A-G) through infancy across cohorts using data-driven clustering analyses. We also demonstrate significant longitudinal changes in microstate dynamics during this period, characterized by more numerous and more rapid transitions between largescale configurations, especially over early infancy. While patterns of sensory microstate development were largely consistent between cohorts, higher-order cognitive microstates showed context-specific developmental trends. Together these results provide novel insights into how large-scale brain networks functionally develop and organize across the first two years of life.