Communications biology
August 5, 2024
Charlotte Maschke, Jordan O'Byrne, Michele Angelo Colombo et al.
50 citations
Consciousness may depend on brain activity poised at criticality—a state with complex patterns and high sensitivity to disruption. Analyzing resting-state EEG from healthy volunteers under propofol, xenon, or ketamine anesthesia, the study found that unconsciousness (from propofol or xenon) shifted brain dynamics away from avalanche criticality and the edge of chaos. Ketamine anesthesia preserved consciousness (vivid dreams) and criticality. Dynamical properties from resting EEG accurately predicted individual values of the perturbational complexity index (PCI), a TMS-based consciousness measure. The findings link perturbational complexity to criticality and suggest criticality is necessary for consciousness.
Progress in brain research
January 1, 2009
Melanie Boly, Marcello Massimini, Giulio Tononi
50 citations
Assessing consciousness in noncommunicative brain-damaged patients is challenging because behavioral responses are limited by motor impairment and cognitive dysfunctions. Recent studies have compared brain activity in comatose, vegetative state, sleep, anesthesia, and epileptic seizure conditions, but no consensus on the brain mechanisms generating consciousness has emerged. The authors argue that combining theoretical approaches with experimental procedures is necessary for a coherent explanation of consciousness loss across these conditions. They review current theories, emphasizing the Integrated Information Theory of Consciousness (IITC), which predicts reduced consciousness in certain states. While technical and conceptual issues limit its clinical applicability, some predictions are testable with available imaging techniques.
Scientific Reports
November 5, 2018
Matthieu Darracq, Chadd M. Funk, Daniel Polyakov et al.
49 citations
Sleep and anesthesia alter conscious experience, which can be absent (unconsciousness) or take the form of dreaming where sensory stimuli are not incorporated (disconnected consciousness). Using transcranial magnetic stimulation-electroencephalography over parietal regions, evoked alpha power (8-12 Hz) decreased during disconnected consciousness in rapid eye movement sleep and ketamine anesthesia compared to wakefulness. In unconscious states of propofol anesthesia and non-rapid eye movement sleep, evoked low-gamma power (30-40 Hz) decreased compared to wakefulness or disconnected consciousness. These findings, confirmed with dream reports from serial awakenings, suggest suppression of evoked alpha activity may mark sensory disconnection.
International Anesthesiology Clinics
January 1, 2008
Pierre Boveroux, Vincent Bonhomme, Melanie Boly et al.
44 citations
A peer-reviewed article examines the intersection of medicine, consciousness, and brain function, focusing on altered states such as those arising from cardiovascular syncope, autonomic disorders, hallucinations in medical conditions, and traumatic brain injury with neurovascular disturbances. The work discusses how these conditions affect cognitive science, psychology, and legal implications, without presenting a single empirical finding or specific numerical data. The argument integrates neuroscience and philately as a metaphor for collecting insights, suggesting that altered states of consciousness can inform understanding of brain function and autonomic regulation.
Psychology of consciousness (Washington, D.C.)
March 1, 2019
Benjamin Baird, Brady A Riedner, Melanie Boly et al.
41 citations
Lucid dreaming occurs more often in long-term meditators than in people who do not meditate. Among non-meditators, lucid dream frequency is linked to the ability to put experience into words, while among meditators it is linked to observing and decentering aspects of mindfulness. However, an 8-week mindfulness course did not increase lucid dream frequency. The findings suggest a continuity between awareness during waking and sleeping states and connect meditation training with meta-awareness, but the precise nature of the link remains unclear.
Consciousness and cognition
January 1, 2022
Benjamin Baird, Mariel Kalkach Aparicio, Tariq Alauddin et al.
17 citations
Spontaneous episodic thoughts about the past and future are common during waking but rarely occur during N2 or REM sleep. Analysis of thought reports from 138 participants who underwent experience-sampling while awake and serial awakenings during sleep shows that waking spontaneous thought frequently includes autobiographical planning with a strong bias toward the future. In contrast, dreaming sleep states rarely feature such mental time travel. This suggests that human consciousness differs substantially across the sleep-wake cycle in how it typically engages with episodic past and future events.
bioRxiv : the preprint server for biology
October 31, 2023
Charlotte Maschke, Jordan O'Byrne, Michele Angelo Colombo et al.
7 citations
preprint
Consciousness may depend on brain activity poised at criticality, a state with optimal computational properties. Electroencephalograms were recorded from healthy, unresponsive volunteers under propofol, xenon, or ketamine anesthesia. Ketamine spared consciousness (vivid dreams), allowing separation of unresponsiveness from unconsciousness. Unconscious states showed a departure from both the edge of activity propagation and the edge of chaos. The perturbational complexity index (PCI), a sensitive consciousness measure, was predicted from these dynamical properties with a mean absolute error below 7%. Results link PCI to criticality and support criticality's role in consciousness.
Frontiers in Neuroscience
February 13, 2024
Benedetta Cecconi, Javier Montupil, Sepehr Mortaheb et al.
6 citations
Disconnected consciousness, where subjective experience persists but is cut off from the external world, often occurs during sleep or sedation but is difficult to study because unresponsive people may still be conscious and amnesia can erase memories of events. This research uses a serial awakening paradigm during mild propofol sedation: participants hear sounds and are interviewed while still sedated to determine whether they are connected or disconnected from the environment, bypassing the need for behavioral responses and amnesia. Functional MRI data reveal neural activity patterns during these states, testing whether sensory disconnection arises at the thalamus or from disrupted information flow to higher brain regions. Slow-wave activity's role is also explored via high-frequency BOLD oscillations. Findings could improve anesthesia monitoring and assessment of patients with reduced consciousness.
Scientific data
May 23, 2025
Alia Seedat, Alex Lepauvre, Jay Jeschke et al.
5 citations
An intracranial EEG dataset was collected from 38 epilepsy patients across three research centers as part of an adversarial collaboration testing Global Neuronal Workspace Theory and Integrated Information Theory. Participants viewed visual stimuli—faces, objects, letters, and false fonts—in three orientations and for three durations, performing a Go/No-Go target detection task. The dataset includes demographics, clinical information, electrode reconstructions, behavioral performance, and eye-tracking data, all converted to BIDS format. It is intended for reuse in consciousness science and vision neuroscience to investigate stimulus processing, target detection, and task-relevance.
bioRxiv Preprint Server
April 18, 2024
Melanie Boly, Richard Smith, Giulietta Vigueras Borrego et al.
5 citations
preprint
A state called pure presence, reported in meditative traditions as a vivid experience without thoughts, perceptions, or self, was examined in twenty-two long-term meditators using high-density EEG. During pure presence, brain activity showed widespread reductions in gamma and delta power compared to mind-wandering, watching a movie, active thinking, and dreamless sleep. The strongest gamma decreases occurred in the posteromedial cortex. These findings align with integrated information theory's prediction that vivid consciousness can arise when the brain's cortical substrate is largely quiet yet highly awake.
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference
July 1, 2019
Minji Lee, Benjamin Baird, Olivia Gosseries et al.
4 citations
Cortical networks show differences in functional integration and segregation across states of consciousness, but not in overall connectivity. In the beta frequency band, functional integration during wakefulness exceeded that during NREM sleep. In the theta band, functional segregation (transitivity and clustering coefficient) was stronger in NREM sleep without conscious experience than in wakefulness or REM sleep, while the opposite pattern appeared in the beta band. No significant differences in the weighted phase lag index were found among wakefulness, REM sleep with conscious experience, NREM sleep with conscious experience, and NREM sleep without conscious experience. These findings may relate to cortical bistability and contribute to understanding neural correlates of consciousness.
Aperture Neuro
March 18, 2026
Melanie Boly
Consciousness is not an epiphenomenon but a prerequisite for most purposeful behaviors in humans. Over the past two decades, consciousness science has advanced from descriptive correlations to mechanistic predictions, with the Perturbational Complexity Index (PCI) from TMS-EEG indicating about a 95% probability of detecting consciousness in non-communicative patients when purposeful behavior is present. Recent studies in neurotypical individuals and communicative patients, using refined statistical methods and awareness scales validated by subjective reports, consistently suggest that some degree of stimulus awareness is necessary for above-chance performance. Consciousness, intelligence, and cognitive abilities can dissociate, motivating Integrated Information Theory, which generates testable predictions about conscious states independently of behavior.
PloS one
January 1, 2026
Clement Abbatecola, Bernard Marius ’t Hart, Belén M. Montabes De la Cruz et al.
The subjective experience of space around the visual blind spot is investigated to test three theories of consciousness: Integrated Information Theory (IIT), Predictive Processing Active Inference (AI), and Predictive Processing Neurorepresentationalism (NREP). IIT predicts that the blind spot region, lacking feedforward input from one eye, should contribute differently to perceived spatial quality. The Predictive Processing accounts argue that internal models accommodate structural deviations based on sensory evidence. Participants evaluate distances, areas, and illusory motion with or without the blind spot involved. Psychometric models quantify bias and precision in perceived versus objective space. Simulated results correspond to each theory's predictions, and challenges for dissemination are discussed.
arXiv Preprint Archive
October 29, 2025
Giulio Tononi, Melanie Boly
Integrated information theory (IIT) takes a 'consciousness-first' approach, arguing that consciousness reveals the essential properties of existence. IIT formulates these properties operationally, yielding postulates of physical existence: to exist intrinsically, an entity must have cause-effect power upon itself in a specific, unitary, definite, and structured manner. The theory claims that an entity's cause-effect structure accounts for all properties of an experience, including spatial extendedness, temporal flow, and qualia such as colors and sounds, with no additional ingredients. IIT has implications for understanding meaning, perception, free will, and for assessing consciousness in patients, infants, other species, and artifacts.
bioRxiv Preprint Server
June 23, 2023
Oscar Ferrante, Urszula Gorska-Klimowska, Simon Henin et al.
preprint
An open science adversarial collaboration directly juxtaposed Integrated Information Theory (IIT) and Global Neuronal Workspace Theory (GNWT) by investigating neural correlates of visual experience. 256 human subjects viewed suprathreshold stimuli for variable durations while neural activity was measured with fMRI, MEG, and ECoG. Information about conscious content was found in visual, ventro-temporal, and inferior frontal cortex, with sustained responses in occipital and lateral temporal cortex reflecting stimulus duration, and content-specific synchronization between frontal and early visual areas.
The Journal of neuroscience : the official journal of the Society for Neuroscience
November 8, 2017
Johan F Storm, Melanie Boly, Adenauer G Casali et al.
The mind-body problem—how consciousness arises from brain processes—has long been considered a philosophical puzzle but is now being tackled empirically. This review describes progress since Crick and Koch (1998) proposed searching for the neural correlates of consciousness (NCC). It covers content-specific NCCs, which link particular brain activity to specific experiences, and the full NCC, which supports entire conscious states. The authors discuss methodological advances for isolating conscious experience from enabling functions, suggest that reconsidering the frontal cortex's role may refine NCCs, advocate for objective brain-based measures of consciousness independent of sensory or executive processes, and show how animal studies reveal network phenomena relevant to consciousness mechanisms.