title: The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers.
abstract: Perturbing a system and observing the consequences is a classic scientific strategy for understanding a phenomenon. Psychedelic drugs perturb consciousness in a marked and novel way and thus are powerful tools for studying its mechanisms. In the present analysis, we measured changes in resting-state functional connectivity (RSFC) between a standard template of different independent components analysis (ICA)-derived resting state networks (RSNs) under the influence of two different psychoactive drugs, the stimulant/psychedelic hybrid, MDMA, and the classic psychedelic, psilocybin. Both were given in placebo-controlled designs and produced marked subjective effects, although reports of more profound changes in consciousness were given after psilocybin. Between-network RSFC was generally increased under psilocybin, implying that networks become less differentiated from each other in the psychedelic state. Decreased RSFC between visual and sensorimotor RSNs was also observed. MDMA had a notably less marked effect on between-network RSFC, implying that the extensive changes observed under psilocybin may be exclusive to classic psychedelic drugs and related to their especially profound effects on consciousness. The novel analytical approach applied here may be applied to other altered states of consciousness to improve our characterization of different conscious states and ultimately advance our understanding of the brain mechanisms underlying them.
authors.affiliation: Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK ; Computational, Cognitive and Clinical Neuroscience Laboratory, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: Leor
authors.initials: L
authors.lastname: Roseman
authors.affiliation: Computational, Cognitive and Clinical Neuroscience Laboratory, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Leech
authors.affiliation: The Beckley Foundation Oxford, UK.
authors.forename: Amanda
authors.initials: A
authors.lastname: Feilding
authors.affiliation: Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Nutt
authors.affiliation: Centre for Neuropsychopharmacology, Division of Brain Sciences, Department of Medicine, Imperial College London London, UK.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Carhart-Harris
keywords: 5HT2A; MDMA; brain networks; functional connectivity; psilocybin; psychedelic; resting state; serotonin