Lifespan Trajectories of Alpha Rhythm: Dynamic Shifts in Neural Excitation-Inhibition Balance

Alpha rhythm (8-13 Hz), a key neural oscillation in the brain, plays a significant role in cognitive functions and reflects the brains excitatory-inhibitory (E-I) balance. This study investigates the dynamics of alpha rhythm across the lifespan, focusing on how E-I balance modulates alpha power and peak frequency, and exploring the distinct age-related and sex-specific patterns of alpha activity. Using a computational E-I model, we simulated the impact of different neuronal connections and E-I ratios on alpha rhythm characteristics. The results suggest that self-regulation primarily affects alpha power, while interaction between excitatory and inhibitory neurons influences both alpha frequency and power. We applied this model to real EEG data from 3265 participants across a wide age range, revealing that alpha power and peak frequency exhibit an inverted U-shape across the lifespan, peaking in early adulthood and declining in old age. Significant sex differences in alpha activity were observed primarily during puberty and later in life. Decomposition of the alpha band into periodic and aperiodic components showed that periodic activity follows the inverted U-shape, while aperiodic activity declines exponentially with age. Our findings indicate that alpha rhythm is governed by complex E-I dynamics, with distinct contributions from periodic and non-periodic components, and highlight the role of alpha rhythm in age-related cognitive changes and sex differences in brain function.