Psilocybin (from Psilocybe mushrooms) increased whole-brain signal complexity and “entropy” by about 6–10%, meaning brain networks became more flexible and information-rich. This didn’t happen with stimulants like amphetamine or MDMA, which showed little change or even reduced network flexibility. The biggest shifts were in the default-mode and emotion-control networks and lasted for hours, showing psilocybin puts the brain into a highly adaptable, less rigid state rather than just a sped-up one.