{Reference Type}: Journal Article {Title}: When Maturation is Not Linear: Brain Oscillatory Activity in the Process of Aging as Measured by Electrophysiology. {Author}: Doval S;López-Sanz D;Bruña R;Cuesta P;Antón-Toro L;Taguas I;Torres-Simón L;Chino B;Maestú F; {Journal}: Brain Topogr {Volume}: 0 {Issue}: 0 {Year}: 2024 Jun 20 {Factor}: 4.275 {DOI}: 10.1007/s10548-024-01064-0 {Abstract}: Changes in brain oscillatory activity are commonly used as biomarkers both in cognitive neuroscience and in neuropsychiatric conditions. However, little is known about how its profile changes across maturation. Here we use regression models to characterize magnetoencephalography power changes within classical frequency bands in a sample of 792 healthy participants, covering the range 13 to 80 years old. Our findings unveil complex, non-linear power trajectories that defy the traditional linear paradigm, with notable cortical region variations. Interestingly, slow wave activity increases correlate with improved cognitive performance throughout life and larger gray matter volume in the elderly. Conversely, fast wave activity diminishes in adulthood. Elevated low-frequency activity during aging, traditionally seen as compensatory, may also signify neural deterioration. This dual interpretation, highlighted by our study, reveals the intricate dynamics between brain oscillations, cognitive performance, and aging. It advances our understanding of neurodevelopment and aging by emphasizing the regional specificity and complexity of brain rhythm changes, with implications for cognitive and structural integrity.