Meditation produces a broad-frequency (15–200 Hz) state-dependent decrease in functional connectivity (phase consistency) between brain regions, while simultaneously enhancing power spectral density (PSD) across the same range. Visual gratings, which boost narrow-band gamma power, reduced gamma FC in both meditators and controls. Aging and gender affected FC only in narrow alpha (8–12 Hz) and high-beta (20–36 Hz) bands. Average referencing severely distorted FC estimates, yielding uninterpretable results. These findings indicate distinct neural mechanisms for meditation, healthy aging, and vision, and caution against using average referencing in phase-based connectivity studies.
Long-term meditators show stronger stimulus-induced gamma oscillations and steeper power spectral density slopes compared to matched controls, suggesting enhanced inhibitory function. Both stimulus-induced and stimulus-free gamma coexist during meditation but arise from different brain regions—occipital and fronto-temporal respectively—indicating distinct mechanisms. Meditation-induced broadband gamma localizes to fronto-temporo-parietal regions, with stronger effects in parietal areas of meditators, while stimulus-induced gamma is stronger in occipital areas. Meditators also report higher mindfulness, lower stress, and more mystical experiences, though these traits do not correlate with gamma power. These findings suggest meditation may boost inhibitory mechanisms and mitigate age-related neural decline.