Journal of Neuroscience
October 4, 2017
Melanie Boly, Marcello Massimini, Naotsugu Tsuchiya et al.
591 citations
The role of the frontal cortex in consciousness is debated. This Perspective critically reviews clinical and neuroimaging evidence for the involvement of the front versus the back of the cortex in specifying conscious contents and discusses promising research avenues.
Trends in Cognitive Sciences
November 13, 2015
Naotsugu Tsuchiya, Melanie Wilke, Stefan Frässle et al.
567 citations
The search for the neural basis of consciousness has been biased by the requirement that subjects report their experiences. Recent no-report paradigms aim to study conscious experience without any report, dissociating neural activity that gives rise to consciousness from activity that enables reporting. The advantages and disadvantages of both report-based and no-report approaches are discussed, and the authors ask how combining these methods can bring us closer to understanding the true neural basis of consciousness.
Frontiers in Psychology
January 1, 2013
Melanie Boly, Anil K. Seth, Melanie Wilke et al.
295 citations
Consciousness research over the last decade has advanced through evidence that fronto-parietal connectivity and top-down processes enable information to travel across distant cortical areas, and through numerous dissociations between consciousness and cognitive functions such as attention in humans. Mental imagery paradigms now allow identification of covert awareness in non-responsive subjects. In non-human animals, technological enhancements have clarified the roles of cortical areas and higher-order thalamus for consciousness, and progress has been made in understanding non-vertebrate cognition relevant to possible conscious states. Major advances have also occurred in theories of consciousness and their comparison with available evidence.
Neuroscience of Consciousness
January 1, 2017
Andrew Haun, Giulio Tononi, Christof Koch et al.
97 citations
Some researchers claim that perceptual experience is impoverished—that people perceive and remember very little visual information. However, the evidence indicates that this view is mistaken and that visual phenomenology is actually immensely rich. To accurately assess perceptual content, experiments should go beyond simple binary forced-choice tasks and instead analyze broader reports of experience. Adopting such methods will reveal the genuine richness of experience and its underlying neural basis.
Science
January 25, 2018
Olivia Carter, Jakob Hohwy, Jeroen J. A. van Boxtel et al.
86 citations
A commentary argues that Dehaene et al.'s review on consciousness and machines asks and answers the wrong questions, implying that their conclusions about not being on the verge of creating conscious machines may be premature or misdirected.
Neuroscience of consciousness
January 1, 2020
William Wong, Valdas Noreika, Levente Móró et al.
35 citations
In a test of whether brain activity alone can reveal when someone is dreaming, researchers used an unsupervised machine learning classifier to distinguish dreamful from dreamless sleep based on EEG spectral power and electrode location. Nine participants contributed 54 one-minute polysomnograms from non-rapid eye movement sleep—27 with dreams and 27 without. A blinded Analysis Team attempted to classify each recording over five iterations with gradually reduced blindness. At no stage did the classifier perform significantly better than chance, indicating that EEG spectral power features could not reliably detect signatures of phenomenal consciousness in this dataset.
May 16, 2023
William Wong, Kátia C. Andrade, Thomas Andrillon et al.
21 citations
preprint
A new open-access database, DREAM, combines sleep magneto/electroencephalography (M/EEG) recordings with standardized dream reports to enable large-scale neurocognitive research on dreaming. The initial release includes 20 datasets from 561 participants and 2649 awakenings, each with at least 20 seconds of high-frequency M/EEG data and a classification of the subject's experience. Analyses demonstrate that features extracted from EEG can predict whether a person reports having had a conscious experience during both REM and NREM sleep. The database aims to overcome the limitations of small sample sizes and methodological variability in dream research, allowing new questions to be addressed at a scale unattainable by individual labs.
Proceedings of the National Academy of Sciences of the United States of America
March 18, 2025
Yusuke Moriguchi, Ryoichi Watanabe, Chifumi Sakata et al.
13 citations
Color qualia—the subjective experience of color, such as the quality of redness—are similar across age and culture. Using a task that obtained pairwise similarity judgments via intuitive visual interfaces, researchers tested children aged 3 to 12 in Japan and 6 to 8 in China, comparing them with Japanese adults. About half of 3-year-olds completed the touch-panel task reliably. Despite developmental and cultural differences in color-term usage, color qualia structures were quite similar across all groups. This suggests that these structures emerge early in life. Subtle age-related differences in evaluations of some color pairs imply minor changes in color experience with development.
Advances in Consciousness Research
June 17, 2015
Jeroen J.a. Van Boxtel, Naotsugu Tsuchiya
11 citations
A chapter examines confounds that must be controlled when studying the neural basis of phenomenal conscious perception. It reviews psychological and neural studies that dissociate attention, report, and memory from phenomenal consciousness, discussing phenomena such as aftereffects, change blindness, inattentional blindness, and brain-imaging results whose implications for consciousness theory may be contaminated by these factors. The chapter also considers whether report and memory are necessary or sufficient for phenomenal consciousness.
Nature communications
August 13, 2025
William Wong, Rubén Herzog, Kátia Cristine Andrade et al.
10 citations
A new open database, the DREAM database, combines standardized sleep magneto/electroencephalography (M/EEG) recordings with dream reports from 505 participants across 20 datasets, totaling 2,643 awakenings. Each awakening includes at least 20 seconds of high-resolution sleep EEG (≥100 Hz, ≥2 electrodes) and a classification of the sleeper's reported experience. Analyses showed that reports of conscious experiences during sleep can be predicted from objective EEG features in both REM and NREM sleep. The database aims to overcome limitations of small sample sizes and methodological variability in dream research, enabling larger-scale investigations of the neurocognitive basis of dreaming.
Frontiers in psychology
January 1, 2024
Naotsugu Tsuchiya, Peter Bruza, Makiko Yamada et al.
8 citations
A new hypothesis called Quantum-like Qualia (QQ) proposes that qualia—the qualities of conscious experience—are best described by the mathematical structure of quantum theory, rather than as points in a dimensional space. The standard view assumes qualia can be measured without changing them, but empirical findings show that internal attention can alter qualia during measurement. QQ treats qualia as observables, sensory inputs and internal attention as states, and measurement outcomes as probabilistic. This structure predicts that qualia can be indeterminate, which can be tested through order effects or violations of Bell inequalities. Confirmation would suggest that quantum mathematics offers novel insights into consciousness.
Frontiers in psychology
January 1, 2023
Marius Usher, Niccolò Negro, Hilla Jacobson et al.
7 citations
The Unfolding Argument (UA) against causal structure theories of consciousness relies on unwarranted assumptions that express a behaviorist methodology, despite its proponents' claims. The same reasoning can be applied to functionalist approaches, proving too much and deeming a wide range of non-causal structure theories unscientific. The authors argue that the UA's philosophical assumptions are overly restrictive and fit poorly with common practice in cognitive neuroscience. They propose a more inclusive methodology for consciousness science that incorporates neural, behavioral, and phenomenological evidence from the first-person perspective. Theories of consciousness should be tested and evaluated on humans, not on systems considerably different from us, thus restricting the range of systems rather than the methodology.
Entropy (Basel, Switzerland)
May 29, 2026
Zoe Lee-Youngzie, Naotsugu Tsuchiya, Michael Robinson et al.
4 citations
A structural approach to consciousness models qualia—the qualities of experience—by examining either the internal organization of parts within an experience or the external relations between experiences. Integrating these two perspectives is a key step toward understanding phenomenally unified global experience. This paper describes both types of structural models and their category-theoretic formalizations, then proposes a sheaf-theoretic framework that maps mereological parts of experience to empirical measures of their qualia. Applying the framework to visual space demonstrates a formal description of experience's structure and conditions for phenomenal unity. The approach supports an empirical research program linking local and global phenomenal qualities.
PLoS biology
July 1, 2025
Angus Leung, Ahmed Mahmoud, Travis Jeans et al.
3 citations
Only 47 out of over 7,700 time-series features reliably distinguished wakefulness from anesthesia or sleep across all evaluation groups of flies. Most of these features were related to autocorrelation, indicating that signals during wakefulness remained correlated to their past for longer than during anesthesia or sleep. Features related to complexity or spectral power, often proposed as consciousness markers, failed to generalize across all datasets, though many showed consistent direction of effect. These results caution that many newly discovered potential consciousness markers may not generalize across datasets, and point to autocorrelation as a class of dynamical properties that does.
Neuroscience of consciousness
January 1, 2025
Francesco Ellia, Naotsugu Tsuchiya
2 citations
A commentary argues that recent computational functionalist theories of consciousness, while making a welcome structural turn, largely echo predictions already made by Integrated Information Theory. The authors question whether key claims—about subjective experience, local lateral connectivity in sensory areas, and the role of silent units—are coherent within the functionalist paradigm. They emphasize the need to distinguish genuine predictions from post-hoc accommodations in consciousness science.
Philosophy and the Mind Sciences
December 23, 2025
Tadahiro Taniguchi, Masafumi Oizumi, Noburo Saji et al.
1 citation
Language emergence and the relational structure of subjective experiences, termed qualia structure, may influence each other bidirectionally. The emergence of languages with distributional semantics, such as syntactic-semantic structures, is hypothesized to link to the coordination of internal representations shaped by experience, potentially facilitating more structured language through reciprocal influence. This mutual dependency is explored through theoretical frameworks like collective predictive coding. Computational studies show that neural network-based language models form systematically structured internal representations, and multimodal language models can share representations between language and perceptual information. Language emergence may serve not only as a communication tool but also as a mechanism for shared understanding of qualitative experiences. The paper outlines future constructive research directions in consciousness studies, linguistics, and cognitive science.
bioRxiv Preprint Server
October 1, 2025
Kallum Robinson, Ariel Zeleznikow-Johnston, Jiahao Wu et al.
1 citation
preprint
The qualitative aspects of consciousness (qualia) are difficult to study because they are subjective. This work takes a first step toward linking the structure of qualia to brain activity by comparing human dissimilarity ratings of visual motion experiences with neural population responses in mouse primary visual cortex. Human participants (N=171) rated dissimilarity of 48 visual motion stimuli. Mouse neural activity (n=751 neurons) was recorded from nine mice using optical imaging. Both human and mouse data showed structural commonalities: a categorical organization of stimulus direction best explained both structures. These commonalities were similar in awake and anaesthetized mice, suggesting coarse V1 geometry is relatively insensitive to this anesthesia. The authors note that future work combining behavior with causal intervention is needed to relate such neural structures to conscious experience.
Mind and Matter
June 30, 2026
J. Díaz-Boils, Naotsugu Tsuchiya, CM. Signorelli
A formal mathematical model, inspired by Husserl's phenomenology, represents structural aspects of conscious experiences as layers that can be experienced in potentiality or actuality. The model shows that comparison among phenomenal experiences is only partial: some experiences are comparable, such as those carrying different aspects in actuality and potentiality, while others are not, such as those with the same number but different aspects in actuality. These results imply that the evolution of consciousness involves diverse modes of experiencing rather than an absolute scale across species. The methodology also clarifies how conceptual assumptions constrain mathematical structure, and how that structure constrains interpretations of phenomenal experience, making formalization transparent.
F1000Research
June 25, 2026
Kyoko Kusano, Hayato Saigo, Naotsugu Tsuchiya
Measuring the diversity of subjective experiences (qualia) is difficult. A new mathematical approach, derived from category theory, offers two indices—'generalized magnitude' and 'spread'—to quantify how varied a person's internal structure of sensations is. In an experiment with 120 participants who rated similarities among color and emotion words, both indices captured differences in qualia structures at the group and individual levels. The indices also reveal complex graphical features of these structures, providing a principled way to compare how diverse people's inner experiences are.
Philosophy and the Mind Sciences
January 31, 2026
Alexander Maier, Naotsugu Tsuchiya
A structural approach to studying consciousness maps mathematical descriptions of qualia—the qualitative aspects of conscious experience—onto mathematical structures derived from brain activity and neuronal connectivity, aiming for general mappings akin to physical laws like E=mc². This review surveys literature from psychophysics and the neuroscience of consciousness, critically examines classical models such as Shepard's pitch helix and visual color space, and explores the structure of their neuronal correlates. It extends analysis to visual similarity spaces, including face space and general image spaces, and suggests that exact experimental comparisons yield an enriched psychophysics that expands single-valued measures into richer scientific exploration.
November 6, 2024
Zoe Lee-Youngzie, Naotsugu Tsuchiya, Martin M. Monti et al.
preprint
Qualia—the subjective qualities of experience—can be modeled either by analyzing the internal organization of parts within a single experience or by examining relations between different experiences. A key challenge is combining these two perspectives into a unified account of global conscious experience. This paper describes both types of structural models and their category-theoretic formalizations, then proposes a sheaf-theoretic framework that links mereological parts of experience to empirical measures of their qualia. An application to visual space demonstrates how this framework formally describes the structure of experience and conditions for phenomenal unity. The approach supports empirical research on the relationship between local and global phenomenal qualities and outlines future work toward a structural characterization of global phenomenal consciousness.
Trends in cognitive sciences
April 7, 2026
Francesco Ellia, Naotsugu Tsuchiya
Contemporary consciousness science is stuck in an impasse because competing theoretical frameworks—such as structuralist versus functionalist, universal versus local, and intrinsic versus extrinsic approaches—are creating philosophical deadlocks and conceptual standstills. These parallel debates have generated insights but lack a systematic framework to understand their relationships. The authors argue that these disputes reflect deeper unresolved tensions in how consciousness is conceptualized. They propose that the debates can be addressed by recognizing three fundamental meta-theoretical dimensions: explanatory medium, scope, and perspective. The interplay among these dimensions shapes evidence, language, and concepts, reframing theoretical conflicts into tractable disagreements.
Neuroscience of consciousness
January 1, 2025
Anikó Kusztor, Nirmitee Mulay, Makiko Yamada et al.
People experiencing depersonalization or derealization often report that the world looks faded, foggy, or dream-like. Two online experiments tested whether these subjective reports reflect genuine changes in visual perception. Participants with varying levels of depersonalization/derealization symptoms rated how real naturalistic images looked (Experiment 1, 200 participants) or adjusted the contrast and saturation of images to match their everyday visual experience (Experiment 2, 125 participants). In both experiments, strong Bayesian evidence supported the null models: symptom severity did not affect realness ratings or vividness adjustments. The results suggest that the altered vividness experience in derealization does not stem from genuine perceptual changes but rather from metacognitive interpretation of those experiences.
Neuroscience of consciousness
January 1, 2025
Elise G Rowe, Ken Takeda, Masafumi Oizumi et al.
Top-down attention affects not just whether we see something, but how we see it—the quality of conscious experience, or qualia. Using a dual-task paradigm, participants rated similarity of stimulus pairs in the periphery for rotated letters, bisected disks, and greyscale faces. Similarity ratings served as a proxy for qualia structures, analyzed with dimension reduction and optimal transport alignment. Attention withdrawal collapsed qualia structures for letters and disks, but alignment accuracy remained high for face qualia structures under both full and poor attention. This relational judgment approach extends previous binary categorization methods and offers a novel way to study qualia structures.
arXiv Preprint Archive
December 13, 2024
Steven Phillips, Naotsugu Tsuchiya
Conscious experience has five essential properties—intrinsicality, information, integration, exclusion, and composition—as proposed by Integrated Information Theory (IIT), but the necessity of these axioms is unclear due to their informal presentation and dependence on a specific mathematical model. A category-theoretic approach, a meta-mathematical framework for making relations between formal structures precise, organizes these five properties around a smaller number of meta-mathematical principles. Category theory characterizes structures by universal mapping properties, a unique-existence condition for all instances. This suggests that the axioms for consciousness correspond to universal mapping properties, leading to the idea that consciousness is a universal property.