Science Advances
February 1, 2019
Athena Demertzi, Enzo Tagliazucchi, Stanislas Dehaene et al.
545 citations
Consciousness depends on the brain's ability to sustain rich, dynamic patterns of signal coordination. Using functional magnetic resonance imaging, a complex pattern of coordinated and anticoordinated signals characterized healthy individuals and minimally conscious patients. Unresponsive patients showed low interareal phase coherence mainly mediated by structural connectivity, with fewer transitions between patterns. This complex pattern was also seen in patients with covert cognition who could perform mental imagery tasks, validating its link to consciousness. Anesthesia increased the probability of the less complex pattern to levels seen in unresponsive patients, confirming its role in unconsciousness. These results establish generalizable fingerprints of conscious and unconscious states after brain damage.
Frontiers in Psychology
August 15, 2018
Christopher Timmermann, Leor Roseman, L. Williams et al.
228 citations
Near-death experiences (NDEs) share striking phenomenological similarities with the effects of the psychedelic drug DMT. In a placebo-controlled, within-subjects study, 13 healthy participants received DMT and placebo, then completed a standard NDE measure. DMT significantly increased NDE-like features compared to placebo. NDE scores were linked to DMT-induced ego-dissolution and mystical experiences, as well as baseline traits of absorption and delusional ideation. Nearly all NDE features overlapped between DMT-induced experiences and a matched group of actual NDE experiencers. These results indicate a remarkable similarity between the DMT state and NDEs, warranting further research.
PLoS ONE
February 14, 2018
Héléna Cassol, Benoît Pétré, Sophie Degrange et al.
131 citations
Near-death experiences (NDEs) are profound psychological events that can significantly affect experiencers' lives. Previous research shows NDE memories are phenomenologically rich. This study analyzed the narratives of 34 cardiac arrest survivors to extract common themes. A qualitative thematic analysis identified 10 'time-bounded' themes—isolated events during the NDE—and 1 'transversal' theme that characterizes the entire narrative, often as a retrospective self-reflective comment. The division into themes provides detailed vocabulary used by experiencers and enables a rigorous description of the phenomenon, ensuring all self-reported manifestations are included.
Frontiers in Systems Neuroscience
August 14, 2019
Vincent Bonhomme, Cécile Staquet, Javier Montupil et al.
109 citations
General anesthesia reversibly alters consciousness without globally shutting down the brain. Depending on the agent and dose, it can produce a complete absence of subjective experience (unconsciousness), a conscious experience without environmental perception (disconnected consciousness, like during dreaming), or oriented consciousness with environmental awareness (connected consciousness). Each state may be followed by explicit or implicit memories. Progress in brain function exploration has improved understanding of neural correlates of consciousness and their alterations during anesthesia, including changes in functional and effective brain connectivity, consciousness network topology, and spatio-temporal dynamics.
Consciousness and cognition
March 1, 2019
Charlotte Martial, Héléna Cassol, Vanessa Charland-Verville et al.
98 citations
Near-death experiences (NDEs) share consistent features across cultures, suggesting a common neurobiological basis. Analyzing semantic similarity between about 15,000 reports from 165 psychoactive substances and 625 NDE narratives, the NMDA receptor antagonist ketamine produced reports most similar to NDEs, followed by Salvia divinorum and serotonergic psychedelics like DMT. The similarity was driven by concepts of self and environmental consciousness, as well as therapeutic, ceremonial, and religious aspects of drug use. Ketamine may serve as a safe experimental model for NDE phenomenology, and endogenous NMDA antagonists might be released near death.
Trends in Cognitive Sciences
January 22, 2020
Charlotte Martial, Héléna Cassol, Steven Laureys et al.
90 citations
Near-death experiences (NDEs) occur during comatose states, challenging the common view that consciousness disappears when the brain shuts down. A new framework distinguishing awareness, wakefulness, and connectedness is needed to understand the phenomenon. Classical NDEs represent internal awareness experienced in unresponsive conditions, constituting an episode of disconnected consciousness. This proposal points toward new directions for NDE research and consciousness science more broadly.
Frontiers in Human Neuroscience
June 13, 2017
Charlotte Martial, Héléna Cassol, Georgios Antonopoulos et al.
85 citations
Near-death experiences (NDEs) often follow a common sequence: an out-of-body experience, moving through a tunnel, seeing a bright light, then feeling peace. However, this sequence occurred in only a small number of experiencers, suggesting that the order of NDE features varies widely among individuals. The study analyzed 154 written NDE narratives from French speakers, using text analysis to infer the timing and frequency of core features. The findings indicate that while a typical pattern exists, it is not universal, and understanding the relationships between features may improve scientific definitions of NDEs.
Journal of Neuroscience
March 23, 2021
Diego Candia‐rivera, Jitka Annen, Olivia Gosseries et al.
81 citations
Heartbeat-evoked responses (HERs) in resting-state EEG can distinguish between postcomatose patients who are unresponsive and those in a minimally conscious state with 87% accuracy, 96% sensitivity, and 50% specificity. HERs provide more accurate classification than random EEG segments not locked to heartbeats or heart rate variability. HER-based consciousness scores correlate with glucose metabolism in the right superior temporal sulcus and right ventral occipitotemporal cortex. HERs reflect consciousness diagnosis based on brain metabolism better than behavior-based diagnosis (77% validation accuracy). These findings suggest HERs capture a capacity for consciousness that does not necessarily translate into intentional overt behavior.
Frontiers in Psychiatry
June 7, 2018
Charlotte Martial, Héléna Cassol, Vanessa Charland-Verville et al.
70 citations
People who report near-death experiences (NDEs) without facing a life-threatening situation score higher on fantasy proneness than those who have NDEs during actual danger, those whose experiences do not meet NDE criteria, and healthy controls. In contrast, individuals who have classical NDEs (during a life-threatening event) show no difference in fantasy proneness compared to matched controls. The intensity of the reported experience correlates positively with engagement in fantasy. These findings suggest that strong fantasy proneness may make some individuals more likely to report NDE-like experiences under suitable physiological or psychological conditions, such as meditation or syncope.
Consciousness and Cognition
November 1, 2020
Charlotte Martial, Jessica Simon, Ninon Puttaert et al.
69 citations
Two scales for measuring near-death experiences (NDEs) were evaluated. The original NDE scale showed several weaknesses. A new 20-item Near-Death Experience Content (NDE-C) scale was developed and validated, revealing a five-factor structure covering relevant dimensions. The NDE-C scale demonstrated very good internal consistency (Cronbach α = 0.85) and concurrent validity (correlations above 0.76). This new reliable scale should facilitate future research on NDEs.
Memory
June 12, 2019
Héléna Cassol, Charlotte Martial, Jitka Annen et al.
60 citations
Near-death experiences (NDEs) are typically positive, but about 14% of 123 NDE accounts were distressing. These distressing NDEs included inverse, hellish, or void types, with inverse and hellish each appearing 8 times and void once. A higher proportion of suicide survivors reported distressing NDEs compared to classical ones. Memories of distressing NDEs were as phenomenologically detailed as those of classical NDEs. The findings suggest distressing NDEs require careful attention to help experiencers integrate them into their identity.
Brain sciences
July 14, 2021
Charlotte Martial, Géraldine Fontaine, Olivia Gosseries et al.
37 citations
People who have had a near-death experience often report a disturbed sense of having a distinct self. In a survey of 100 individuals who scored 27 or higher out of 80 on the Near-Death-Experience Content scale, 80 had their experience in a life-threatening situation and 20 did not. Participants completed inventories measuring ego dissolution and ego inflation during their NDE, as well as a scale of nature-relatedness. Ego-dissolution scores were higher than ego-inflation scores. Total NDE intensity positively correlated with ego dissolution and, more weakly, with ego inflation and nature-relatedness. Ego dissolution also correlated with the intensity of out-of-body experiences and a sense of unity. The findings suggest that dissolved ego-boundaries are a common feature of NDEs.
Scientific reports
October 1, 2019
Charlotte Martial, Armand Mensen, Vanessa Charland-Verville et al.
36 citations
A proof-of-concept study induced near-death experience (NDE)-like features in five volunteers who had previously had a pleasant NDE by having them recall the memory under hypnosis while their brain activity was recorded with high-density EEG. The hypnosis protocol recreated NDE-like features without adverse effects and increased absorption and dissociation compared to normal consciousness recall. Recalling the NDE phenomenology was associated with increased alpha brain activity in frontal and posterior regions. The methodology offers a controlled way to prospectively study NDE-like features and their EEG correlates.
BJA Open
September 26, 2023
Javier Montupil, Paolo Cardone, Cécile Staquet et al.
32 citations
The source of consciousness is widely thought to be within the brain, and anesthesiologists have their own operational definition based on observations during anesthesia. The full functional correlates of consciousness remain unclear, but several theories have gained varying support from experiments, including those using anesthesia to reversibly alter aspects of consciousness. Understanding these mechanisms could improve patient management by enabling monitoring devices that detect different states during anesthesia: unconsciousness, internal awareness with or without conscious perception of the environment (connected or disconnected consciousness). Unresponsiveness does not guarantee absence of connectedness or consciousness. This narrative review presents current knowledge from a system-level perspective, highlighting anesthesia's contribution to theories of consciousness and proposing future research directions.
Scientific Reports
September 22, 2023
Victor Oswald, Audrey Vanhaudenhuyse, Jitka Annen et al.
24 citations
Self-induced cognitive trance (SICT) is a voluntary non-ordinary state of consciousness involving narrowed awareness, hyper-focused immersion, and altered perception. This study examined autonomic nervous system changes during SICT by measuring heart rate variability and respiration rate variability in 25 proficient participants across three conditions: resting state, SICT, and a mental imagery task. During SICT, participants showed increased heart rate, decreased high-frequency heart rate variability, and specific increases in respiratory amplitude, phase ratio, and respiration rate variability compared to control conditions. These findings suggest SICT is associated with reduced parasympathetic activity, indicating a hyperarousal state of the autonomic nervous system.
Consciousness and Cognition
July 8, 2017
Charlotte Martial, Vanessa Charland-Verville, Héléna Cassol et al.
24 citations
Memories of near-death experiences (NDEs) are detailed and stable over time, yet their rich phenomenology lacks a satisfactory explanation. In 152 individuals who reported a classical NDE during life-threatening conditions, the intensity of the NDE was positively correlated with phenomenological characteristics of the memory, such as sensory details, personal importance, and frequency of reactivation. Those who described more intense NDEs also reported more vivid and detailed memories of the event.
NeuroImage
June 1, 2024
Pradeep Kumar G, Rajanikant Panda, Kanishka Sharma et al.
20 citations
High-order interactions between brain regions, measured as synergistic and redundant information, change differently across three non-ordinary states of consciousness. During Rajyoga meditation, synergy increased across the whole brain in delta and theta brainwave bands, while redundancy decreased in frontal, central, and posterior electrodes in delta and beta bands. During hypnosis, synergy decreased in mid-frontal, temporal, and mid-centro-parietal electrodes in the delta band, and in left frontal and right parietal electrodes in the beta2 band. During auto-induced cognitive trance, synergy decreased in delta and theta bands in left-frontal, right-frontocentral, and posterior electrodes, and at the whole brain level in the alpha band. Redundancy changes during hypnosis and auto-induced cognitive trance were not significant. Subjective reports of absorption, dissociation, and mystical experience did not correlate with the high-order measures.
Nature reviews. Neurology
June 1, 2025
Charlotte Martial, Pauline Fritz, Olivia Gosseries et al.
19 citations
Near-death experiences (NDEs) are episodes of disconnected consciousness with prototypical mystical features, often occurring during actual or perceived physical threat. Various explanatory theories have been proposed, but integration has been limited. Converging evidence from neuroscience—including non-human studies, psychedelic-induced mystical experiences, and research on the dying brain—now offers a comprehensive explanation. This Review discusses psychological and neurophysiological processes underlying NDEs, including cellular and electrophysiological brain network changes and neurotransmitter alterations. The authors propose a model encompassing a cascade of concomitant processes within an evolutionary framework and consider how NDE research informs debates on consciousness emergence near brain death.
Neurosci Conscious
June 15, 2024
Paolo Cardone, Naji Alnagger, Jitka Annen et al.
16 citations
Psychedelic substances, already being tested for psychiatric conditions like depression and PTSD, might also help people with disorders of consciousness caused by brain injury. The article discusses the rationale for using complexity-enhancing psychedelics in post-comatose patients, proposing an optimal level of brain complexity for recovery. It examines how psychedelics and disorders of consciousness may have counterintuitive effects on the default mode network and selfhood. Computational modeling could complement experimental studies to clarify treatment mechanisms and enable personalized medicine. The authors update ethical considerations for this clinical and scientific endeavor.
Neuroscience of Consciousness
January 1, 2019
Héléna Cassol, Arnaud D’Argembeau, Vanessa Charland‐verville et al.
16 citations
People who report near-death experiences (NDEs) often consider those memories central to their identity, regardless of whether the experience occurred during actual physical danger. Among 71 participants screened with the Greyson NDE scale, 48 had real NDEs and 23 had NDE-like experiences without life threat. Those who recalled their NDE (41 total) rated it as more central to their identity than other self-defining memories. Richer NDE memories were associated with greater centrality. The findings suggest that the self-defining nature of NDEs relates more to their phenomenological content than to the circumstances of occurrence, highlighting the importance of integrating these memories into personal identity.
Brain Structure and Function
January 1, 2021
Jitka Annen, Rajanikant Panda, Charlotte Martial et al.
15 citations
A world champion free diver's brain activity and connectivity shift markedly during a 6.5-minute breath-hold. EEG shows increased alpha wave power and connectivity, with decreased delta band connectivity. fMRI reveals heightened connectivity within the default mode network and visual areas, but reduced connectivity in sensorimotor cortices. These changes overlap with some meditation-related brain signatures but also include unique features suggesting altered somatosensory integration. Self-reports indicate that elite free divers may achieve a state of sensory dissociation during prolonged apnea, reflecting their ability to adapt psychologically and physiologically to extreme breath-holding.
Journal of cognitive neuroscience
September 1, 2023
Charlotte Martial, Héléna Cassol, Mel Slater et al.
13 citations
Out-of-body experiences (OBEs) can be partially induced in a virtual reality setup. Seven healthy participants wore a VR headset and saw their virtual body from a ceiling viewpoint; in one condition their real movements were mirrored onto the virtual body, in the other they were not. Participants reported strong sensations of floating and being high up, but only weak to moderate feelings of being out of their body. Brain activity recorded with 128 electrodes showed that these subjective experiences were linked to increased delta and decreased alpha power, reduced theta complexity, and increased beta-2 connectivity, supporting the idea that delta activity plays a prominent role in certain conscious states.
Frontiers in Human Neuroscience
April 28, 2023
Aminata Bicego, Héléna Cassol, Jessica Simon et al.
13 citations
Spiritual beliefs, Openness to experience, and Fantasy proneness are associated with recalling a near-death experience (NDE) or an NDE-like experience (similar phenomenology without a life-threatening context). In a retrospective study of 181 people divided into four groups—NDE experiencers, NDE-like experiencers, controls who faced a life-threatening situation without an NDE, and controls with neither—multivariate logistic regression showed that spiritual beliefs predicted NDE-like recall, while Openness and Fantasy proneness predicted NDE recall. A discriminant analysis using these variables correctly classified only 35% of cases, indicating other factors also play a role.
NeuroImage
September 1, 2024
Charlotte Martial, Andrea Piarulli, Olivia Gosseries et al.
10 citations
During fainting, some people have dream-like experiences with extraordinary, mystical features similar to near-death experiences. In 22 healthy volunteers who fainted under controlled conditions, eight reported such near-death-like features. Their brain activity showed higher electrical activity in delta, theta, and beta2 frequency bands in temporal and frontal regions, including the insula, right temporoparietal junction, and cingulate cortex. The richer the experience, the stronger the activity in these areas. The brains of those with near-death-like experiences also showed more complex, more connected, and more integrated neural networks compared to those without such experiences. These surges of neural activity may mark disconnected consciousness during fainting.
iScience
January 17, 2025
Paolo Cardone, Arthur Bonhomme, Vincent Bonhomme et al.
9 citations
In a small double-blind, placebo-controlled, cross-over trial with three adults who had prolonged disorders of consciousness after a coma, an intravenous sub-anesthetic dose of the atypical psychedelic ketamine increased brain complexity as measured by Lempel-Ziv complexity, but did not change the explainable consciousness indicator. Patients showed reduced spastic paresis and spent more time with their eyes open, yet their diagnosis of consciousness did not improve. No adverse effects occurred. The findings suggest a potential therapeutic role for ketamine in disorders of consciousness and support a link between brain complexity and conscious states.