Summary The quest for reliable and objective measures of consciousness is critical in basic and clinical neuroscience. Across species, the perturbational complexity index (PCI) has emerged as a robust empirical marker by directly perturbing the brain, yet its relationship to broader physical principles remains unclear. Here, we address this gap by introducing a non-invasive framework based on generative whole-brain models of non-equilibrium brain dynamics. Using these models, we identify violations of the fluctuation-dissipation theorem (FDT) in humans and rodents across wakefulness, anesthesia, and disorders of consciousness (DoC). Mirroring PCI, FDT violations decrease in unresponsive DoC and anesthesia compared with conscious conditions. These findings reveal a robust empirical link between PCI and non-equilibrium dynamics in spontaneous brain signals, suggesting that non-equilibrium dynamics capture an important aspect of perturbational complexity. Overall, this framework opens non-invasive, model-based avenues for understanding consciousness and supports efforts to assess its loss and recovery in health and disease.
T. Berjaga-Buisan, J. Monti, Martina Cortada et al.· Cell Reports· 1 citation
Background Consciousness is increasingly understood as an emergent property of large-scale brain dynamics that depend upon flexible interactions among distributed cortical and subcortical systems. Although disorders of consciousness (DOC) have traditionally been associated with impaired integration and reduced network complexity, the role of hierarchical brain organization in supporting conscious awareness remains poorly understood. Here, we investigated how hierarchical organization relates to behavioral responsiveness in DOC by combining trophic-level analysis, trophic coherence, and whole-brain dynamical metrics. Methods Resting-state functional MRI data were analyzed from healthy controls (CNT), minimally conscious state (MCS) patients, and unresponsive wakefulness syndrome (UWS) patients drawn from a previously published DOC cohort. Static global and regional measures of functional hierarchy were computed from directed effective-connectivity networks. Dynamic trophic states were identified using time-resolved phase-coupling analyses and clustering of recurrent coordination patterns. State occupancy, dwell time, metastability, synchrony, and behavioral associations with Coma Recovery Scale–Revised (CRS-R) scores were evaluated. Results Regional trophic levels were positively associated with behavioral responsiveness, with higher frontal and thalamic trophic levels and lower insular trophic levels predicting higher Coma Recovery Scale–Revised (CRS-R) scores. Dynamic trophic-state analysis identified a pathological hyper-hierarchical state, defined by elevated frontal, thalamic, and insular trophic levels, that exhibited progressively greater occupancy and longer dwell times from healthy controls to minimally conscious state and unresponsive wakefulness syndrome patients. In contrast, occupancy and dwell time of this state distinguished diagnostic groups but were not significantly associated with behavioral responsiveness. Independent analyses demonstrated significant reductions in metastability and global synchrony across disorders of consciousness. Anatomical mapping localized elevated trophic levels within the pathological state predominantly to fronto-thalamo-limbic systems. Conclusions Disorders of consciousness are characterized not simply by loss of hierarchical organization but by prolonged stabilization within recurrent hyper-hierarchical brain states. Conscious awareness appears to depend not only on hierarchical organization itself but also on the capacity to flexibly transition between distinct brain states. Severe disorders of consciousness are associated with persistent occupation of pathological hyper-hierarchical states, potentially restricting the dynamical repertoire available for conscious processing.
K. Olaciregui-Dague, I. Acero-Pousa, T. Berjaga-Buisan et al.· bioRxiv· 0 citations
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. Key points UBEs are associated with a global flattening of brain hierarchy measured by EEG. UBEs are associated with increased global EEG complexity, resembling the psychedelic state.
Teresa Campillo-Ferrer, T. Berjaga-Buisan, A. Iadarola et al.· bioRxiv· 0 citations
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