PLoS Computational Biology
October 16, 2014
Srivas Chennu, Paola Finoia, Evelyn Kamau et al.
249 citations
Consciousness is thought to require balanced integration and differentiation of brain activity, supported by efficient networks. Analyzing high-density EEG from 32 patients with chronic disorders of consciousness and healthy controls, the authors found that patient networks showed reduced local and global efficiency and fewer hubs in the alpha frequency band. A new metric, modular span, revealed that alpha network modules in patients were spatially limited, lacking the long-distance interactions seen in controls. However, delta and theta band networks were partially reversed and more similar to each other in patients. Alpha network efficiency correlated with behavioral awareness. Notably, some behaviorally unresponsive vegetative patients with covert awareness had well-preserved alpha networks resembling controls, suggesting network mechanisms that may support consciousness despite severe behavioral impairment.
Cerebral cortex (New York, N.Y. : 1991)
June 30, 2020
Andrés Canales-Johnson, Alexander J Billig, Francisco A Olivares et al.
51 citations
During auditory bistable perception, a sequence of tones can be heard either as a single stream (integrated percept) or as two parallel streams (differentiated percept). Neural recordings showed that when perceptual alternations arose spontaneously, the integrated percept corresponded to increased neural information integration and decreased neural information differentiation across frontoparietal regions, while the differentiated percept showed the opposite pattern. When perception was driven by an external change in the sound stream, neural oscillatory power distinguished between percepts but information measures did not. The findings demonstrate that integration and differentiation of conscious perception map onto theoretically motivated neural information signatures, suggesting a direct link between phenomenology and neurophysiology.
bioRxiv (Cold Spring Harbor Laboratory)
September 23, 2021
Pedro A. M. Mediano, Aleksi Ikkala, Rogier Kievit et al.
30 citations
preprint
Neural complexity measures, which can distinguish conscious from unconscious states, also detect meaningful fluctuations in conscious level during normal wakefulness. Using MEG and fMRI data from healthy adults, complexity decreased as participants became drowsy, validating the approach. Complexity changed within and between tasks, and higher complexity was associated with better performance and faster reaction times on an executive task. This offers a new way to explore the cognitive and neural basis of consciousness.
Cerebral cortex (New York, N.Y. : 1991)
August 1, 2024
Evan Lewis-Healey, Enzo Tagliazucchi, Andrés Canales-Johnson et al.
27 citations
Intentional breathing techniques (breathwork) can induce altered states of consciousness similar to those produced by psychedelics. By tracking subjective experiences moment-by-moment alongside portable EEG recordings across 301 sessions from 14 novice participants, researchers found that psychedelic-like experiences—especially intense bliss—corresponded with increased neural complexity (Lempel-Ziv complexity) and changes in the aperiodic exponent of brain activity, but not with alpha brainwave power. These non-linear neural features map onto both broad positive experiences and specific psychedelic-like states, suggesting breathwork alters consciousness through mechanisms distinct from simple relaxation or meditation.
bioRxiv Preprint Server
March 4, 2022
Barbara Jachs, Manuel Camino Garcia, Andrés Canales-Johnson et al.
21 citations
preprint
A new method called Temporal Experience Tracing captures aspects of conscious experience continuously over time, allowing computational reconstruction of common experience states. Analyzing 852 meditations from 20 novice and 12 experienced meditators practicing Breathing, Loving-Kindness, and Open-Monitoring meditation, four recurring experience states were identified, averaging 6 minutes 46 seconds each. Three states matched the three meditation styles, and a fourth represented a low-motivational off-task state. Both groups spent more time in the task-related state during Loving-Kindness meditation and were less likely to transition to the off-task state compared to Breathing meditation. The method transforms the time dimension of subjective experience from narrative to measurable.
The European journal of neuroscience
March 1, 2022
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A. M. Mediano et al.
16 citations
Neural complexity, measured by the Lempel-Ziv (LZ) compression algorithm, is lowest during NREM sleep and similar during REM sleep and wakefulness in cats with intracranial electrodes. Under subanaesthetic doses of ketamine (5, 10, and 15 mg/kg), complexity follows an inverted U-shaped curve in some electrodes, primarily in prefrontal cortex, rising at low doses and falling as doses approach anaesthetic levels. The variability in the ketamine dose-response curve across cats and cortices was larger than across sleep stages, highlighting differential local dynamics. These results replicate findings in humans and other species, showing neural complexity is sensitive to changes in conscious state.
bioRxiv Preprint Server
June 25, 2021
Claudia Pascovich, Santiago Castro-Zaballa, Pedro A. M. Mediano et al.
7 citations
preprint
Neural complexity, measured by the Lempel-Ziv compression algorithm, is lowest during NREM sleep and similar during REM sleep and wakefulness in cats with intracranial electrodes. Under subanesthetic doses of ketamine (5, 10, and 15 mg/kg), complexity follows an inverted U-shaped curve in some electrodes, especially in prefrontal cortex, rising at low doses and falling as doses approach anesthetic levels. Variability in the ketamine dose-response across cats and cortices is larger than sleep-stage differences, revealing distinct local dynamics. These results replicate findings in humans and other species, showing neural complexity is sensitive to conscious state changes and dose-dependent ketamine effects.
bioRxiv Preprint Server
December 19, 2024
Evan Lewis-Healey, Carla Pallavicini, Federico Cavanna et al.
1 citation
preprint
A dose of the fast-acting psychedelic DMT rapidly reorganizes conscious experience and brain dynamics, but the link between neural complexity and subjective effects is weaker than previously thought. Nineteen participants received 20 mg or 40 mg of DMT in two sessions. The higher dose produced more extreme visual hallucinations and emotionally intense experiences. Contrary to earlier claims, Lempel-Ziv complexity—a measure of neural signal diversity—was the least strongly associated neural marker of the psychedelic state. The findings suggest the relationship between neural complexity and phenomenology during psychedelic experiences is less clear than originally hypothesized.
bioRxiv
May 4, 2026
Tomás Ariel D’amelio, Tomás Gil Garbagnoli, Jerónimo Rodríguez Cuello et al.
Inhalation of DMT, a serotonergic psychedelic, produces a brief surge in sympathetic nervous system activity—heart rate, skin conductance, and respiration—that closely tracks the intensity of the emotional experience. Nineteen participants received 20 or 40 mg of DMT under a semi-naturalistic blinded design. Higher doses caused heart rate and breathing to increase within the first two minutes, while skin conductance rose only later, indicating a prolonged autonomic response. As the drug's effects waned, feelings of pleasantness and bliss emerged. Combining simple physiological measures with moment-by-moment self-reports offers a way to objectively characterize psychedelic-induced emotional states, which may aid future clinical biomarker research.
The Journal of neuroscience : the official journal of the Society for Neuroscience
March 18, 2026
Christine Blume, Marina Dauphin, Maria Niedernhuber et al.
During sleep, the human brain continues to process unexpected sounds, but the neural code becomes delayed, more redundant, and less rich as consciousness wanes. Twenty-nine participants heard an oddball sequence of tones while awake and during an 8-hour sleep opportunity. Prediction error responses occurred in all sleep stages (N1, N2, N3, REM). Mutual information analysis showed a substantial reduction in encoded prediction error information, especially during N3 and REM, even though electrical brain responses (ERPs) grew larger in deeper NREM sleep. Co-information analysis revealed that neural dynamics became increasingly redundant with deeper sleep. The neural code differed between wakefulness and sleep but was largely shared between N2 and N3 stages.
Neuroscience of Consciousness
July 12, 2024
P. Pérez, D. Manasova, B. Hermann et al.
A framework is introduced that characterizes neuronal markers of consciousness along two dimensions: how well they distinguish conscious from non-conscious states (x-axis) and how well they distinguish different conscious contents (y-axis). Using electroencephalography markers of connectivity, complexity, and spectral summaries, the framework is applied to healthy participants during a nap and patients with disorders of consciousness for the state dimension, and to healthy participants in visual awareness and auditory local-global paradigms for the content dimension. Separate clusters of markers with correlated and anticorrelated dynamics emerge, highlighting the complex relationship between the state and content of consciousness and the need to consider them together.
Trends in Neurosciences
April 1, 2024
Célia Lacaux, Mélanie Strauss, Tristan A Bekinschtein et al.
The sleep-onset period (SOP), the transition from wakefulness to sleep, has been largely overlooked despite its potential importance. This review synthesizes current knowledge about the SOP in humans, examining its definition and limits, the dynamic electrophysiological changes that accompany falling asleep, and the interplay between internal and external processing during this transition. The authors propose that the SOP may offer cognitive benefits and identify novel directions for better diagnosing sleep-onset disorders. The review highlights recent findings that have reignited interest in this transitional period, shedding light on its neural mechanisms, cognitive dynamics, and clinical implications.
Neuroimage
April 1, 2018
Ezequiel Mikulan, Eugenia Hesse, Lucas Sedeño et al.
Gamma-band neural synchrony is thought to be important for cortical computation and consciousness, but prior evidence has been inconclusive due to methodological issues. By using intracranial EEG in three participants with implanted electrodes, researchers compared high-gamma connectivity (90-120 Hz) during passive wakefulness versus non-REM sleep. Connectivity and graph-theory measures were higher during wakefulness and distinguished the two states better than other frequency bands. This is the first intracranial EEG report of wake-sleep differences in high-gamma activity at both local and distant brain sites, highlighting the technique's value for studying neural correlates of consciousness.
Frontiers in Psychology
January 1, 2015
Valdas Noreika, Andrés Canales-Johnson, Justin Koh et al.
During the transition from relaxation to drowsiness, people often experience hypnagogic phenomena such as perceptual imagery or linguistic intrusions—sudden, unpredictable anomalies in inner speech. In a single participant across 10 EEG sessions, drowsiness depth (measured by Hori stages) increased in the 20 seconds before reporting such an experience, and EEG Dimension of Activation values decreased, indicating rapid changes in brain predictability. Linguistic intrusions were associated with higher alpha and gamma power over the left hemisphere, while perceptual imagery corresponded to higher beta power over the right hemisphere. These results suggest that the modality and incongruence of hypnagogic experiences have distinct EEG signatures, and sleep onset offers a way to study the neural basis of consciousness fragmentation in healthy individuals.
Frontiers in Psychology
May 22, 2014
Srivas eChennu, Tristan A Bekinschtein
The interplay between top-down and bottom-up attention and consciousness is often examined during sleep, sedation, and disorders of consciousness such as the vegetative state (VS) and minimally conscious state (MCS). The auditory oddball paradigm, which elicits the mismatch negativity (MMN) and P300 event-related potentials, is a common tool for assessing cognitive processing in these contexts. The P300 wave can be separated into the earlier P3a, linked to bottom-up attention, and the later P3b, linked to top-down attention. Emerging evidence from healthy volunteers and patients reveals dissociations between attention and awareness across these states, highlighting neurophysiological and cognitive parallels and differences that inform theoretical frameworks.