Richer than we thought: neurophysiological methods reveal rich-club network development is frequency- and sex-dependent.

A set of highly connected brain regions called the "rich-club" are vital in integrating information across the functional connectome. Although the literature has identified some changes in rich-club organization with age, little is known about potential sex-specific developmental trajectories, and neurophysiologically relevant frequency-dependent changes have not been established. Here we examine the frequency- and sex-dependent development of rich-club organization using magnetoencephalography in a large normative sample ( = 383) over a wide age span (4-39 years). We report strong divergence between males and females across alpha, beta, and gamma frequencies. While males show increased or no change in rich-club organization with age, females show a consistent, non-linear trajectory that increases through childhood, shifting direction in early adolescence. Using neurophysiological modalities for capturing complex inter-relations between oscillatory dynamics, age, and sex, we establish diverging, sex-specific developmental trajectories of the brain's core functional organization, critically important to our understanding of brain health and disease.