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.

Neural correlates of the LSD experience revealed by multimodal neuroimaging

“…10). Thus, in the same way the neurobiology of psychedelicinduced visual hallucinations can inform on the neurobiology of visual processing, so the neurobiology of psychedelic-induced egodissolution can inform on the neurobiology of the "self" or "ego" (37), and the present results extend our understanding in this regard, implying that the preservation of DMN integrity, PH-RSC communication, and regular oscillatory rhythms within the PCC may be important for the maintenance of one's sense of self or ego.…”

The neural correlates of the awe experience: Reduced default mode network activity during feelings of awe

“…For instance, several recent studies have used psychedelic drugs, such as psilocybin or LSD, to induce experiences of "ego dissolution" (i.e., the disappearance of the notion of a core-self), showing that this experience is accompanied by a reduced activation of the DMN (Lebedev et al, 2015;Palhano-Fontes et al, 2015) and decreased functional connectivity within the DMN (Palhano-Fontes et al, 2015;Tagliazucchi et al, 2016). For instance, several recent studies have used psychedelic drugs, such as psilocybin or LSD, to induce experiences of "ego dissolution" (i.e., the disappearance of the notion of a core-self), showing that this experience is accompanied by a reduced activation of the DMN (Lebedev et al, 2015;Palhano-Fontes et al, 2015) and decreased functional connectivity within the DMN (Palhano-Fontes et al, 2015;Tagliazucchi et al, 2016).…”

“…Neuroimaging studies focusing on psychedelics, flow and meditation provide indirect support for the hypothesis that the experience of awe is accompanied by a reduced activation of the DMN. For instance, several recent studies have used psychedelic drugs, such as psilocybin or LSD, to induce experiences of "ego dissolution" (i.e., the disappearance of the notion of a core-self), showing that this experience is accompanied by a reduced activation of the DMN (Lebedev et al, 2015;Palhano-Fontes et al, 2015) and decreased functional connectivity within the DMN (Palhano-Fontes et al, 2015;Tagliazucchi et al, 2016). Furthermore, experimentally induced flow (i.e., a state of perceived fit between skills and task demands while engaging in a particular activity, such as gaming)…”

Effects of LSD on music-evoked brain activity

“…The precuneus is a highly connected hub region that plays an important role in self-referential cognition (Buckner et al, 2008;Cavanna and Trimble, 2006) and emotion-regulation (Cavanna and Trimble, 2006;Schilbach et al, 2012), and shows desynchronized activity under psychedelics (Carhart-Harris et al, 2016a;Muthukumaraswamy et al, 2013a;Riba et al, 2002). This disorganising effect of psychedelics on precuneus activity has been associated with "ego-dissolution", characterised by increased emotional lability (Carhart-Harris et al, 2016a;Lebedev et al, 2015;Tagliazucchi et al, 2014Tagliazucchi et al, , 2016. Although the precuneus is activated by music-evoked emotion (Baumgartner et al, 2006;Koelsch, 2014;Trost et al, 2012), the region shows poor anatomical (Cavanna and Trimble, 2006) and resting state functional connectivity (Tomasi and Volkow, 2012) with auditory regions.…”

“…Psychedelics activate the serotonin 2A receptor (Glennon et al, 1984;Titeler et al, 1988;Vollenweider et al, 1998), and produce an altered state of consciousness that is characterised by marked reductions in functional coupling within high-level brain networks (Carhart-Harris et al, 2012, 2016aPalhano-Fontes et al, 2015), but simultaneous increased cross-talk between low-level areas (Tagliazucchi et al, , 2016. This network "collapse" is thought to be a core mechanism underlying their subjective effects, that include a dissolving of the usual sense of self-hood, increased emotionality and vivid mental imagery Lebedev et al, 2015) and a profoundly altered subjective experience of music (Kaelen et al, 2015).…”