title: Finding the self by losing the self: Neural correlates of ego-dissolution under psilocybin.
abstract: Ego-disturbances have been a topic in schizophrenia research since the earliest clinical descriptions of the disorder. Manifesting as a feeling that one's "self," "ego," or "I" is disintegrating or that the border between one's self and the external world is dissolving, "ego-disintegration" or "dissolution" is also an important feature of the psychedelic experience, such as is produced by psilocybin (a compound found in "magic mushrooms"). Fifteen healthy subjects took part in this placebo-controlled study. Twelve-minute functional MRI scans were acquired on two occasions: subjects received an intravenous infusion of saline on one occasion (placebo) and 2 mg psilocybin on the other. Twenty-two visual analogue scale ratings were completed soon after scanning and the first principal component of these, dominated by items referring to "ego-dissolution", was used as a primary measure of interest in subsequent analyses. Employing methods of connectivity analysis and graph theory, an association was found between psilocybin-induced ego-dissolution and decreased functional connectivity between the medial temporal lobe and high-level cortical regions. Ego-dissolution was also associated with a "disintegration" of the salience network and reduced interhemispheric communication. Addressing baseline brain dynamics as a predictor of drug-response, individuals with lower diversity of executive network nodes were more likely to experience ego-dissolution under psilocybin. These results implicate MTL-cortical decoupling, decreased salience network integrity, and reduced inter-hemispheric communication in psilocybin-induced ego disturbance and suggest that the maintenance of "self"or "ego," as a perceptual phenomenon, may rest on the normal functioning of these systems.
authors.affiliation: Aging Research Center, Karolinska Institutet & Stockholm University, Sweden.|Centre for Age-Related Medicine, Stavanger University Hospital, Norway.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Lebedev
authors.affiliation: Aging Research Center, Karolinska Institutet & Stockholm University, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Lövdén
authors.affiliation: Department of Brain and Cognitive Sciences, Ben-Gurion University of the Negev, Israel.
authors.forename: Gidon
authors.initials: G
authors.lastname: Rosenthal
authors.affiliation: The Beckley Foundation, Beckley Park, United Kingdom.
authors.forename: Amanda
authors.initials: A
authors.lastname: Feilding
authors.affiliation: Division of Brain Sciences, Department of Medicine, Centre for Neuropsychopharmacology, Imperial College London, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Nutt
authors.affiliation: Division of Brain Sciences, Department of Medicine, Centre for Neuropsychopharmacology, Imperial College London, United Kingdom.
authors.forename: Robin L
authors.initials: RL
authors.lastname: Carhart-Harris
mesh_terms: D000328:Adult; D001921:Brain / Q000187:drug effects* / Q000502:physiology*; D001931:Brain Mapping; D004532:Ego; D005260:Female; D006213:Hallucinogens / Q000494:pharmacology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010465:Perception / Q000187:drug effects* / Q000502:physiology*; D025341:Principal Component Analysis; D011562:Psilocybin / Q000494:pharmacology*; D012649:Self Concept
chemical_list: D006213:Hallucinogens; D011562:Psilocybin
keywords: connectivity; consciousness; ego-disturbances; fMRI; graph theory; ichstörungen; medial temporal lobe; psychedelics; psychosis; sense of self