Language-associated brain representations covary with disruption of selfhood under psilocybin

Language helps organise experience into an idiosyncratic, temporally extended sense of self. We therefore used fMRI to investigate whether greater similarity between participants in the activity of language-associated brain regions accompanied psilocybin-induced loss of selfhood. Participants heard music and viewed moving clouds at baseline and after 19 mg psilocybin. At each brain location and time point, we tested whether similarity increased with each pair's summed rank on the Ego Dissolution Inventory (EDI; N=43). We grouped independent components of these associations by time course and decoded each group's map with Neurosynth. Elementary visual imagery (SI; N=49) and baseline activity served as comparators. Under psilocybin, one group formed a distributed, left-lateralised frontotemporal network matching the Neurosynth language map (r=.382, spatial-null p<.001, q=.003), nearly twice the largest comparator estimate (SI: r=.208, p=.004, q=.028; baseline: r<.12). In exploratory analyses, resting-state connectivity of this network decreased with posterior visual cortex and increased with thalamic and frontal regions. Participants with higher EDI scores showed larger changes (Spearman's rho=.455, Bonferroni-adjusted p=.048; SI: rho=.008), most strongly for items describing loss of ego or identity (rho=.43 to .51). We propose that language-associated systems incorporate each person's semantic and autobiographical context into experience, and that disrupting them contributes to loss of ego and identity.