Flattened brain hierarchy and increased EEG complexity during unusual bodily experiences and out-of-body experiences

Authors

Campillo-Ferrer, T., Berjaga-Buisan, T., Iadarola, A., Vohryzek, J., Cordani, R., Veneruso, M., Sanz Perl, Y., Nobili, L., Oostenveld, R., Kringelbach, M. L., Deco, G.

Abstract

Experiences in which the sense of the body becomes distorted offer a unique window into how the brain constructs the bodily self. Despite their clinical relevance in conditions such as depersonalization and body-image disorders, large-scale brain dynamics underlying unusual bodily experiences (UBEs) remain poorly understood, and no prior study has examined them systematically across wakefulness and sleep. Here, we analyzed a high-density EEG dataset including 36 UBE episodes, such as floating sensations, distorted body boundaries, and out-of-body experiences, recorded across rapid eye-movement (REM) sleep, light sleep, sleep arousals, and wakefulness during meditation (N=20). We quantified the temporal irreversibility of neural dynamics, a marker of cortical hierarchical organization, and complemented these analyses with whole-brain signal complexity measures following a within-subject design. UBEs were consistently associated with a global reduction in neural irreversibility and cortical hierarchical differentiation relative to non-UBEs and wakefulness, along with a concurrent increase in whole-brain complexity to levels comparable to wakefulness. Together, these findings suggest that UBEs reflect a neural state combining high informational richness with a transient flattening of cortical hierarchy, a profile that resembles that observed in psychedelic states.

Preprint server: bioRxiv
The authors list and abstract were imported from bioRxiv on 05 Aug 2026.

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