Resting-state brain dynamics: insights from oscillatory activity in brain networks

Our understanding of brain function has shifted from a focus on localized processing to an emphasis on dynamic interactions among distributed neuronal assemblies connected through structural networks. The resting state provides an ideal condition to study these processes, free from task-related influences. Early work highlighted the role of electrophysiological oscillations in facilitating long-range synchronization, while later neuroimaging studies revealed large-scale networks characterized by correlated hemodynamic activity. Multimodal approaches have linked these hemodynamic signals to their electrophysiological origins, offering insights into the neural basis of resting-state connectivity. Electrophysiological studies also show that synchronization patterns evolve rapidly, underscoring the brain's dynamic nature. These oscillatory changes in distributed networks are thought to support behavioral flexibility by modulating task representations in real time. Importantly, altered oscillatory dynamics are implicated in a range of neuropsychiatric and neurological disorders, and neuromodulatory interventions often aim to normalize oscillatory patterns. This review synthesizes evidence from electrophysiology and neuroimaging on resting-state brain dynamics, with a focus on synchronized oscillatory activity. We will examine how oscillations contribute to long-range neuronal communication, discuss models describing mechanisms underlying functional interactions between distant regions, and highlight the promise of multimodal approaches for clarifying the temporal structure of brain networks and their relevance to flexible cognition.