Brain maturation in adolescence: Concurrent changes in neuroanatomy and neurophysiology

TLDR

Adolescence to early adulthood is a period of dramatic brain transformation, yet the link between concurrent structural and functional changes remains unclear. The study examined how age affects neuroanatomy and neurophysiology in 138 healthy subjects aged 10–30 using MRI and resting EEG. MRI data were segmented into gray and white matter and parcellated into large-scale regions, while absolute EEG power was quantified for each lobe across slow-wave, alpha, and beta bands. Gray matter volume declined across age, especially in adolescence, with a parallel curvilinear decrease in slow-wave EEG power, whereas white matter volume increased in the parietal lobe; these patterns suggest gray matter loss reflects neuropil reduction and synapse elimination driving the EEG power decline.

Abstract

Adolescence to early adulthood is a period of dramatic transformation in the healthy human brain. However, the relationship between the concurrent structural and functional changes remains unclear. We investigated the impact of age on both neuroanatomy and neurophysiology in the same healthy subjects (n = 138) aged 10 to 30 years using magnetic resonance imaging (MRI) and resting electroencephalography (EEG) recordings. MRI data were segmented into gray and white matter images and parcellated into large-scale regions of interest. Absolute EEG power was quantified for each lobe for the slow-wave, alpha and beta frequency bands. Gray matter volume was found to decrease across the age bracket in the frontal and parietal cortices, with the greatest change occurring in adolescence. EEG activity, particularly in the slow-wave band, showed a similar curvilinear decline to gray matter volume in corresponding cortical regions. An inverse pattern of curvilinearly increasing white matter volume was observed in the parietal lobe. We suggest that the reduction in gray matter primarily reflects a reduction of neuropil, and that the corresponding elimination of active synapses is responsible for the observed reduction in EEG power.