Trends in Cognitive Sciences
June 1, 2022
Pedro A. M. Mediano, Fernando E. Rosas, Daniel Bor et al.
109 citations
The integrated information theory of consciousness (IIT) proposes a universal mathematical formula derived from fundamental properties of conscious experience to describe the quality of consciousness. The theory is ambitious in that it aims to derive a mathematical measure of integrated information from consciousness itself, using properties of conscious experience to characterize the quality of consciousness. The text repeatedly states that IIT is a theory of consciousness that proposes a mathematical formula derived from fundamental properties of conscious experience to describe the quality of consciousness, but it does not provide specific findings, numbers, or empirical results.
Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences
May 23, 2022
Pedro A. M. Mediano, Fernando E. Rosas, Andrea I. Luppi et al.
73 citations
Emergence—how galaxies form or consciousness arises from neurons—lacks formal tools for rigorous study. This article summarizes, elaborates, and extends a recent formal theory of causal emergence based on information decomposition, which is quantifiable and empirically testable. The theory links emergence to information about a system's temporal evolution that cannot be obtained from its parts separately. The article provides an accessible but rigorous introduction to this framework, discussing its merits in various scenarios, interpretation issues, and potential misunderstandings, highlighting the distinctive benefits of this formalism.
ACS chemical neuroscience
February 7, 2024
Pedro A M Mediano, Fernando E Rosas, Christopher Timmermann et al.
60 citations
LSD increases brain entropy (neural signal diversity) across all conditions, but the effect is strongest when eyes are closed. Brain entropy changes correlate with subjective psychedelic experience ratings, except when viewing a video, possibly because external stimuli compete with LSD-induced imagery. This shows context modulates neural dynamics during psychedelic experiences, highlighting the importance of environment in psychedelic psychotherapy.
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.
Neuroscience of Consciousness
November 1, 2021
Andrea I. Luppi, Pedro A. M. Mediano, Fernando E. Rosas et al.
42 citations
Consciousness can be better understood by decomposing it into distinct information-theoretic elements rather than measuring it as a single quantity of integrated information. The authors propose Integrated Information Decomposition (ΦID), which provides a formal argument that whether consciousness is an emergent phenomenon depends on its information-theoretic composition. Two organisms may have the same amount of integrated information yet differ in composition. A new measure, ΦR, and the ΦR-ing ratio quantify how efficiently information is used for conscious processing. This approach enables identification of qualitatively different 'modes of consciousness' and mapping them to phenomenology, starting with selfhood. ΦID offers new ways to explore the relationship between information, consciousness, and neural dynamics.
bioRxiv (Cold Spring Harbor Laboratory)
November 2, 2020
Pedro A. M. Mediano, Fernando E. Rosas, Christopher Timmermann et al.
39 citations
preprint
Psychedelics reliably increase brain entropy (neural signal diversity), an effect linked to psychological changes and opposite to the decrease seen during loss of consciousness. This study investigated how context—specifically stimulus manipulation—modulates that entropy increase. Participants under LSD or placebo experienced eyes-closed versus eyes-open conditions, or no stimulus, music, or video. Brain entropy rose with LSD across all conditions but was largest with eyes closed. Entropy changes consistently matched subjective ratings of the psychedelic experience, except during video viewing, suggesting competition between external stimuli and internal LSD-induced imagery. The findings provide quantitative evidence that context shapes neural dynamics during psychedelic experiences, supporting the practice of eyes-closed psychedelic psychotherapy, and challenge simplistic views of brain entropy as a direct measure of conscious level.
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.
NeuroImage
November 1, 2022
Hardik Rajpal, Pedro A M Mediano, Fernando E Rosas et al.
23 citations
Schizophrenia and drug-induced states from LSD and ketamine both increase neural signal diversity, but they differ in brain connectivity: schizophrenia shows increased information flow from front to back of the brain, while the drugs reduce it. These differences can be modeled by altering Bayesian inference in a predictive processing framework: drug effects correspond to reduced precision of prior beliefs, whereas schizophrenia involves increased precision of sensory information. The findings clarify similarities and differences between these altered states, with implications for understanding consciousness and developing mental health treatments.
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 (Cold Spring Harbor Laboratory)
November 9, 2023
Fernando E. Rosas, Pedro A. M. Mediano, Christopher Timmermann et al.
14 citations
preprint
Autonomic signals can reveal aspects of subjective and neural states. A Bayesian framework estimated heart rate entropy under psychedelics. Across four drugs—LSD, DMT, psilocybin, and ketamine—mean heart rate, high-frequency heart rate variability, and heart rate entropy consistently increased during the psychedelic experience. These changes predicted various dimensions of the experience. Heart rate entropy increases correlated with brain entropy increases, while other autonomic markers did not. Cost-efficient autonomic measures can reveal detail about subjective and brain states, opening new research avenues in neuroscience.
Pedro A.M. Mediano, Fernando E. Rosas, Andrea I. Luppi et al.
10 citations
A new method called Complexity via State-space Entropy Rate (CSER) estimates neural signal complexity with better temporal resolution and spectral decomposition than the standard Lempel-Ziv complexity (LZ) approach. CSER matches LZ in distinguishing conscious states but offers two key advantages: it can break complexity down by frequency bands, and it provides temporal resolution about 100 times finer. Using MEG, EEG, and ECoG data from humans and monkeys, CSER revealed that gamma-band activity primarily drives complexity changes across states of consciousness. In an auditory mismatch negativity experiment, CSER detected early entropy increases roughly 20 milliseconds before the standard event-related potential. This method enables finer-grained study of how signal complexity relates to cognitive processes and conscious states.
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.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
December 9, 2019
David J Schwartzman, Daniel Bor, Nicolas Rothen et al.
7 citations
Synaesthesia, where specific stimuli automatically trigger additional perceptual experiences, offers insight into conscious perception. While traditionally considered congenital, growing evidence shows that synaesthesia-like experiences can be induced in non-synaesthetes, even in adulthood. This review examines various methods for artificially inducing such experiences and compares them to natural synaesthesia's hallmarks: consistency, automaticity, and lack of 'perceptual presence'. The authors conclude that many aspects of synaesthesia can be induced, suggesting developmental and learning components in its acquisition and extending evidence of perceptual plasticity in adults.
bioRxiv
February 1, 2022
Hardik Rajpal, Pedro A.M. Mediano, Fernando E. Rosas et al.
5 citations
preprint
Schizophrenia and drug-induced states from LSD and ketamine both increase neural signal diversity, but they differ in how information flows in the brain. In schizophrenia, transfer entropy from the front to the back of the brain is increased, whereas under both drugs it is reduced overall. These differences can be modeled by altering Bayesian inference within a predictive processing framework: drug effects correspond to reduced precision of prior beliefs, while schizophrenia corresponds to increased precision of sensory information. The findings clarify similarities and differences between these altered states, with potential implications for understanding consciousness and developing mental health treatments.
Andrea I. Luppi, Pedro Mediano, Fernando Rosas et al.
5 citations
preprint
Consciousness can be understood not as a single unified thing but as composed of distinct information-theoretic elements. A new approach called Integrated Information Decomposition (ΦID) shifts from measuring how much integrated information a system has to analyzing its composition. This provides a formal way to determine whether consciousness is an emergent phenomenon based on that composition. Two organisms can have the same amount of integrated information yet differ in its composition. A new measure, ΦR, and the ΦR-ing rate quantify how efficiently an entity uses information for conscious processing. This decomposition identifies qualitatively different 'modes of consciousness,' enabling mapping between phenomenology and information-theoretic structure, starting with selfhood.
bioRxiv Preprint Server
August 3, 2020
David. J. Schwartzman, Aleš Oblak, Nicolas Rothen et al.
4 citations
preprint
Grapheme-colour synaesthesia (GCS) involves automatic, consistent colour experiences triggered by letters or numbers. Two recent studies showed that extensive associative training can produce behavioural, neurophysiological, and phenomenological markers of synaesthesia in non-synaesthetes, but they did not deeply compare the induced experiences to natural synaesthesia. This study analyzed interview transcripts from participants who underwent such training and from natural synaesthetes. Both groups shared several experiential categories, including stability, location, shape, relative strength, and automaticity of colour experience. However, automaticity differed significantly: natural synaesthetes mostly reported automatic experiences, while induced synaesthesia-like experiences were mostly described as wilful. Additional categories emerged only in natural synaesthetes, highlighting heterogeneity. The results indicate that intensive training can alter conscious perception, producing phenomenology substantially resembling natural synaesthesia.
eLife
July 18, 2024
Andrea I Luppi, Pedro A M Mediano, Fernando E Rosas et al.
1 citation
Loss of consciousness significantly disrupts the brain's ability to integrate information. In a study involving functional MRI analysis, it was revealed that gateway regions in a 'synergistic global workspace' correspond to the default mode network, while broadcaster regions align with the executive control network. This integration breakdown occurs during general anaesthesia or disorders of consciousness, with recovery restoring functionality. The findings enhance understanding of consciousness by bridging Global Neuronal Workspace and Integrated Information Theory, highlighting the critical role of brain networks in maintaining conscious experience.
arXiv Preprint Archive
April 13, 2026
Adam B. Barrett, Borjan Milinkovic, Pedro A. M. Mediano et al.
The integrated information theory of consciousness (IIT) proposes a mathematical formula, derived from fundamental properties of conscious experience, to describe the quantity and quality of consciousness for any physical system. This article clarifies common misunderstandings. A high value of the measure Φ does not mean 'more consciousness'; Φ might be replaced with a suite of quantities for a multidimensional characterization. IIT implies a distinct panpsychism where space and time are tiled with substrates of proto-consciousness, which the authors find unproblematic. Φ is not well-defined for real physical systems and has never been computed on one; only proxies have been computed, not approximations. For IIT to align with fundamental physics, a reformulation in continuous fields would be needed.
NeuroImage
February 11, 2023
Andrea I. Luppi, Pedro A.M. Mediano, Fernando E. Rosas et al.
High-level brain functions are thought to arise from coordinated activity across neural systems, but this has been hard to test empirically. Using a framework called Integrated Information Decomposition, which quantifies emergence in dynamical systems, the authors analyzed functional MRI data and found that emergent and hierarchical neural dynamics are significantly reduced in chronically unresponsive patients with severe brain injury. Emergence capacity was positively correlated with hierarchical organization in brain activity. Combining network control theory and whole-brain modeling, the authors show that reduced emergent and hierarchical dynamics in these patients can be explained by disruptions in the structural connectome. The results suggest that chronic unresponsiveness after severe brain injury may stem from structural damage to neural infrastructure needed for emergent brain dynamics.
Alzheimer's & dementia (New York, N. Y.)
January 1, 2021
Jonathan D Huntley, Stephen M Fleming, Daniel C Mograbi et al.
People with Alzheimer's disease show a range of changes in consciousness, including reduced awareness of cognitive deficits, diminished self-awareness, and impaired introspection, which appear early and worsen as the disease progresses. These awareness impairments are linked to brain damage in areas that overlap with proposed neural correlates of consciousness. The authors argue that recognizing Alzheimer's disease as a disorder of consciousness is overdue and important for understanding patients' lived experience and improving care.