LSD alters brain activity by increasing alpha and beta brain-wave frequencies while genuinely reducing oscillatory power, with these effects showing distinct cortical patterns. The drug also flattens the aperiodic 1/f spectral slope and increases neural signal fractality and complexity, particularly in sensory, language, emotion, and imagery-related networks, while sparing motor cortex. Machine learning identified peak-frequency shifts, aperiodic parameters, and complexity measures as key discriminators of the psychedelic state. Music did not amplify these neural signatures and showed a trend toward attenuation. These findings provide a comprehensive account of how LSD reorganizes large-scale human brain dynamics.
Lysergic acid diethylamide (LSD) loosens the brain's usual alignment between anatomical structure and neural activity in a frequency-dependent way. Low-frequency brain waves (theta, alpha, beta) become less constrained by the structural connectome, indicating a global relaxation of large-scale dynamics. High-frequency gamma activity shows selective reorganization rather than uniform disruption. Greater gamma-band decoupling within core default-mode network regions predicts the intensity of ego dissolution across individuals. LSD does not cause indiscriminate disintegration but drives system-specific rebalancing: visual and attentional systems decouple while auditory networks strengthen coupling. These findings suggest psychedelic states emerge from frequency-dependent relaxation of structural constraints, with default-mode reorganization as a neural correlate of ego dissolution.