Four methods of inducing altered states of consciousness—psilocybin, LSD, hypnosis, and meditation—produce distinct patterns of brain connectivity, not a single shared neural signature. Pharmacological and nonpharmacological interventions showed connectivity patterns that could predict which method a person had used. Hypnosis and meditation differed from each other and from the drugs. Psilocybin and LSD did not differ in brain connectivity but showed different relationships between brain activity and behavior. The findings clarify how each method works in the brain and suggest they may offer different therapeutic avenues for psychiatric disorders.
Hypnosis alters functional connectivity in brain networks involving parieto-occipital-temporal areas, cuneal/precuneal and occipital cortices, lingual gyri, and the occipital pole. Comparing two hypnotic states revealed depth-dependent connectivity changes in left superior temporal/supramarginal gyri, cuneus, planum temporale, and lingual gyri. Respiration rate slowed significantly during hypnosis. These findings provide insights into the neurobiology of altered consciousness.