Brain function relies on the flexible integration of signals from specialized regions. The contribution of distinct brain regions to the reconfiguration of brain network dynamics is uneven, with some regions showing a high degree of variability in connectivity and other regions maintaining a relatively stable repertoire of functional connections across time. The spatiotemporal renegotiation of whole-brain functional connectivity can be spontaneous, or induced by behavioral task demands, sensory inputs, and brain stimulation. Motivated by recent advances, this talk will discuss the role of a hierarchy of timescales (following a core-periphery axis of the human connectome) in these processes of reconfiguration. A constellation of densely interconnected regions plays a central role in promoting a stable dynamical core. In contrast, peripheral regions show rapidly fluctuating dynamics involved in fast perceptual processes. Moreover, brain stimulation may cause opposite effects in functional connectivity if the target regions are at the core or at the periphery of the network. These contrary effects are part of a continuous tuning curve that represents how different brain regions respond to stimulation depending on their hierarchical position. These findings highlight the importance of the core-periphery axis in shaping brain dynamics.
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