Age-related changes in normalized spectral properties. (A) Group-level spectra of normalized electroencephalogram power as a function of age in the frontal (top row) and parietal (bottom row) brain regions across the baseline, maintenance, and recovery periods. (B) Spearman correlation between age and normalized electroencephalogram power in the frontal and parietal brain regions for each frequency band across the baseline, maintenance, and recovery periods. *Significant correlation with P < 0.05.