Maturation of Neuronal Activity in the Human Cortex Exhibits Robust Spatial Gradients across the Birth Transition

Early structural and molecular development of the human cortex is extensively studied, but little is known about the development of neuronal activity across cortical regions. We used dense array electroencephalography recordings and a machine learning-based measure, functional brain age (FBA), to study spatiotemporally resolved maturation of cortical activity across the birth transition in human infants (male and female). We found clear spatial FBA gradients indicating more mature frontal cortical activity relative to other brain regions (geometric axis), as well as more mature activity in association cortices relative to sensory cortices (hierarchical axis). The frontal advance was explained by more mature bursting characteristics, a hallmark of early endogenous neuronal activity. The findings jointly support an advanced maturation of neuronal ensemble activity in cortical regions that are preparing to host synergistic, large-scale network interactions, a key global characteristic of mature brain function.