Science
September 7, 2006
Adrian M. Owen, Martin R. Coleman, Melanie Boly et al.
1,974 citations
A patient who met the clinical criteria for a vegetative state showed brain activity indistinguishable from healthy volunteers when asked to imagine playing tennis or moving around her home. Using functional magnetic resonance imaging, the patient activated the same predicted cortical areas as conscious individuals, indicating preserved conscious awareness despite appearing unresponsive. This finding suggests that some patients diagnosed as vegetative may retain covert consciousness that standard behavioral assessments cannot detect.
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.
Trends in Cognitive Sciences
April 22, 2016
Tim Bayne, Jakob Hohwy, Adrian M. Owen
443 citations
The concept of a level of consciousness is central to the science of consciousness, used to describe global states in post-comatose disorders, epileptic absence seizures, anesthesia, and sleep. However, what a level of consciousness actually means remains unclear. This paper argues that the levels-based framework for understanding global states of consciousness is untenable and instead proposes a multidimensional account of global states.
Science Advances
June 14, 2023
Leor Roseman, Christopher Timmermann, Daniel Golkowski et al.
65 citations
The effects of mind-altering drugs on brain function arise from complex interactions with multiple neurotransmitter systems, not just one. By linking the distribution of 19 neurotransmitter receptors and transporters (measured with PET) to changes in functional connectivity (measured with fMRI) caused by 10 drugs—anesthetics (propofol, sevoflurane, ketamine), psychedelics (LSD, psilocybin, DMT, ayahuasca), and others (MDMA, modafinil, methylphenidate)—the work shows a many-to-many mapping between drug effects and neurotransmitter systems. The drugs' impacts follow hierarchical gradients of brain structure and function, and regional susceptibility to drug-induced changes mirrors susceptibility to structural alterations from brain disorders.
bioRxiv
November 26, 2020
Andrea I. Luppi, Pedro A.M. Mediano, Fernando E. Rosas et al.
49 citations
preprint
The brain coordinates information from many sources to create a unified conscious experience. Combining network science and information theory, the authors identify a “synergistic global workspace” where gateway regions gather synergistic information from specialized brain modules, integrate it, and then broadcast it widely via broadcaster regions. Functional MRI shows that gateway regions correspond to the default mode network and broadcasters to the executive control network. Loss of consciousness from general anesthesia or disorders of consciousness reduces the workspace’s ability to integrate information, which is restored upon recovery. This work reconciles aspects of the Global Neuronal Workspace and Integrated Information Theory.
Communications Biology
September 30, 2024
Pablo Castro, Andrea I. Luppi, Enzo Tagliazucchi et al.
21 citations
Brain activity during unconsciousness, whether from general anaesthesia or slow wave sleep, is dominated by a recurrent functional connectivity pattern primarily mediated by structural connectivity and with a reduced capacity to transition to other patterns. Conscious awareness is characterized by richer brain dynamics measured by entropy and a greater repertoire of connectivity states. These findings suggest that the dynamic exploration of functional connectivity states provides robust and generalizable markers for the state of consciousness across different conditions.
bioRxiv (Cold Spring Harbor Laboratory)
July 13, 2022
Andrea I. Luppi, Justine Y. Hansen, R. Adapa et al.
5 citations
preprint
Psychoactive drugs reshape brain function by engaging multiple neurotransmitter systems simultaneously. By mapping the distribution of 19 neurotransmitter receptors and transporters (via PET) and the connectivity changes caused by 10 drugs (anesthetics, psychedelics, and stimulants), the study shows that drug effects are organized along hierarchical gradients of brain structure and function. Additionally, brain regions susceptible to drug-induced changes are also vulnerable to structural alterations from brain disorders. These findings reveal systematic links between molecular neurochemistry and large-scale functional reorganization.
bioRxiv
December 17, 2024
Dian Lyu, Ram Adapa, Robin L. Carhart-Harris et al.
preprint
The default mode network (DMN) and frontoparietal control network (FPCN), typically anticorrelated at rest in healthy brains, show continuous rather than absolute anatomical boundaries in the posterior precuneus. Connectivity differences along the dorsal-ventral axis follow linear slopes, forming functional gradients that exist only within each network's territory. These gradients flatten in altered states of consciousness (ASC), with the gradient magnitude similarly impaired across different ASC types, while spatial entropy differs between psychedelic and sedative states. The findings suggest the DMN and FPCN, though appearing distinct, may originate from a single integrated mechanism, and the loss of functional differentiation between them characterizes altered conscious states.
bioRxiv Preprint Server
October 20, 2024
Peter Coppola, Adrian M. Owen, David K. Menon et al.
preprint
A new method captures the brain dynamics unique to each person's subjective experience. Using fMRI while people listened to a story awake and under different levels of anaesthesia, the approach tracks moment-to-moment changes in functional connectivity without assuming common brain states across individuals. The default mode network's dynamics were more dissimilar between conscious participants, reflecting personal engagement with the story. In contrast, the auditory and posterior dorsal attention networks showed higher similarity across conscious individuals, supporting more generalizable experiences. Conscious brain dynamics were more complex for individual-specific patterns but less complex for shared patterns.
bioRxiv Preprint Server
April 12, 2021
Peter Coppola, Lennart R.b. Spindler, Andrea I. Luppi et al.
preprint
The diversity of brain dynamics within small-world network topology, measured as sample entropy (dSW-E), consistently predicts levels of awareness across sedation and disorders of consciousness, even after accounting for underlying functional connectivity dynamics. Both subcortical and cortical areas show predictive value, but subcortical regions exhibit higher and more robust effect sizes. The dynamic reorganization of the functional information architecture, especially in the subcortex, emerges with awareness and offers explanatory power beyond the complexity of dynamic functional connectivity alone.
bioRxiv Preprint Server
June 7, 2026
Andrea I. Luppi, Dragana Manasova, Justine Y. Hansen et al.
preprint
Functional connectivity in the awake human brain is shaped primarily by cognitive co-activation—the tendency of brain regions to work together during mental tasks—more than by structural or molecular constraints. This predominance is systematically lost across five datasets involving pharmacological and pathological perturbations of consciousness (chronic disorders of consciousness; anesthesia with sevoflurane, propofol, or ketamine), when cognition is disconnected from the environment or abolished. During such states, the predictors of functional architecture shift away from cognitive co-activation and toward anatomical and molecular constraints.
bioRxiv Preprint Server
November 20, 2020
Mor Regev, Andrea R. Halpern, Adrian M. Owen et al.
preprint
When people imagine music they have previously memorized, the brain's auditory cortices show melody-specific activity patterns similar to those during actual listening. Functional MRI data from participants who memorized six one-minute instrumental pieces revealed that during silent imagery, these patterns reappeared in right associative auditory cortices. Adding rhythmic tapping while imagining extended the melody-specific neural patterns to both left and right associative cortices. The findings suggest that the contents of conscious auditory experience are encoded similarly during imagery and perception, and that rhythmic motion can enhance the reinstatement of neural patterns associated with complex sounds, supporting models of motor-to-sensory influences in auditory processing.
bioRxiv Preprint Server
January 15, 2019
Sina Khajehabdollahi, Pubuditha M. Abeyasinghe, Adrian M. Owen et al.
preprint
Using the critical Ising model of the brain, integrated information—a measure of consciousness—was measured in toy models of generic neural networks. Monte Carlo simulations were run on 159 random weighted networks analogous to small 5-node neural network motifs. Integrated information, as a type of order parameter like magnetism, undergoes a phase transition at the model's critical point, where the system's 'consciousness' is maximally susceptible to perturbations and on the boundary between ordered and disordered forms. This adds evidence that the emergence of consciousness coincides with self-organized criticality, evolution, the emergence of complexity, and the integration of complex systems.