and was used extensively in psychological research and psychiatric practice in the 1950s and 1960s . In spite of this, however, there have been no modern human imaging studies of its acute effects on the brain. Here we studied the effects of LSD on intrinsic functional connectivity within the human brain using fMRI. High-level association cortices (partially over- lapping with the default-mode, salience, and fron- toparietal attention networks) and the thalamus showed increased global connectivity under the drug. The cortical areas showing increased global connectivity overlapped significantly with a map of serotonin 2A (5-HT2A) receptor densities (the key site of action of psychedelic drugs ). LSD also increased global integration by inflating the level of communication between normally distinct brain net- works. The increase in global connectivity observed under LSD correlated with subjective reports of ‘‘ego dissolution.’’ The present results provide the first evidence that LSD selectively expands global connectivity in the brain, compromising the brain’s modular and ‘‘rich-club’’ organization and, simulta- neously, the perceptual boundaries between the self and the environment.
Crossley, N., Feilding, A., Carhart-Harris, R., Murphy, K., Roseman, L., Tagliazucchi, E., … Orban, C. (2016). Increased Global Functional Connectivity Correlates with LSD-Induced Ego Dissolution. Current Biology, 26(8), 1043–1050. https://doi.org/10.1016/j.cub.2016.02.010