Nature reviews. Neuroscience
April 20, 2016
Christof Koch, Marcello Massimini, Melanie Boly et al.
1,654 citations
The neural correlates of consciousness—the minimum neural mechanisms sufficient for any one specific conscious percept—are primarily localized to a posterior cortical hot zone that includes sensory areas, rather than to a fronto-parietal network involved in task monitoring and reporting. Some candidate neurophysiological markers of consciousness have proved illusory, while measures of differentiation and integration of neural activity offer more promising quantitative indices of consciousness.
Nature reviews. Neuroscience
April 1, 2002
Geraint Rees, Gabriel Kreiman, Christof Koch
742 citations
No Summary
Annals of the New York Academy of Sciences
March 1, 2008
Giulio Tononi, Christof Koch
615 citations
This review synthesizes recent findings on the neural correlates of consciousness, distinguishing consciousness from other brain functions. It examines global changes in consciousness during sleep, anesthesia, and seizures, then explores paradigms for studying neural correlates of specific conscious percepts, highlighting the roles of different brain regions. Dynamic aspects of neural activity—sustained versus phasic, feedforward versus reentrant, and neural synchronization—are discussed. The review also considers how theoretical analysis of consciousness's fundamental properties can complement neurobiological research.
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.
Scholarpedia
January 1, 2007
Florian Mormann, Christof Koch
154 citations
Consciousness is a puzzling property of complex biological systems that depends on their state. The central question is how immaterial conscious mental states relate to physical brain states. Scientists are using various empirical approaches to investigate the neural basis of consciousness. This article reviews those approaches and summarizes what has been learned so far.
IEEE Spectrum
May 29, 2008
Christof Koch, Giulio Tononi
134 citations
Within a generation, people may have the option to upload their minds—thoughts, memories, and personality—to a computer, offering an alternative to death. Once consciousness is reduced to electronic patterns, it could be copied, edited, sold, pirated, bundled with other minds, or deleted. The text raises the question of whether one would sell their soul on eBay, framing the ethical and practical implications of digital immortality and the commodification of consciousness.
PLoS ONE
February 10, 2023
Lucia Melloni, Liad Mudrik, Michael Pitts et al.
106 citations
An adversarial collaboration between proponents of Global Neuronal Workspace and Integrated Information Theory devised and preregistered two experiments that test contrasting predictions about the location and timing of correlates of visual consciousness. Six theory-impartial laboratories will follow the study protocol using fMRI, M-EEG, and intracranial EEG, with built-in replications between labs and within datasets. The project aims to provide decisive evidence for or against the two theories and clarify the neural footprints of conscious visual perception, while modeling large-scale, collaborative, and open science practice.
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.
Nature
June 1, 2025
Oscar Ferrante, Urszula Gorska-Klimowska, Simon Henin et al.
94 citations
Different theories explain how subjective experience arises from brain activity. An open science adversarial collaboration directly juxtaposed integrated information theory (IIT) and global neuronal workspace theory (GNWT). Human participants (n = 256) viewed suprathreshold stimuli for variable durations while neural activity was measured with fMRI, MEG, and intracranial EEG. Information about conscious content was found in visual, ventrotemporal, 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. These results align with some predictions of IIT and GNWT but substantially challenge key tenets of both theories, including a lack of sustained posterior cortex synchronization for IIT and a lack of ignition at stimulus offset and limited prefrontal representation for GNWT.
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.
bioRxiv Preprint Server
March 19, 2017
Melanie Boly, Marcello Massimini, Naotsugu Tsychiya et al.
56 citations
preprint
The role of the frontal cortex in consciousness is debated. This perspective critically reviews clinical and neuroimaging evidence on whether the front or back of the cortex specifies conscious contents, and discusses promising research avenues. The authors argue that current evidence does not clearly support a primary role for the frontal cortex in generating conscious experience, pointing instead to posterior regions as more directly involved. They suggest that future research should focus on distinguishing neural correlates of consciousness from prerequisites and consequences.
Cell reports
July 22, 2025
Christof Koch
1 citation
Inhaling a high dose of the psychedelic 5-methoxy-N,N-dimethyltryptamine profoundly slows down brain activity, but unlike other psychedelics, it does not significantly reduce alpha band power in the electroencephalogram.
Journal of neuroscience methods
July 4, 2026
Parsa Seyfourian, Lydia C Marks, Leslie D Claar et al.
Pupil diameter is a non-invasive biomarker of brain state, correlating with arousal, attention, cognitive processing, and consciousness. Existing pupillometry software often lacks scalability and robustness across diverse experimental conditions and species. Pupil-DLC is an open-source, offline, DeepLabCut-based pipeline for scalable, marker-less pupil tracking, primarily designed for mice. Trained on 21,909 manually annotated frames from over 140 videos of head-fixed mice spanning wakefulness and drug-induced states, including psychedelics and anesthesia, the dataset was deliberately selected to maximize pupil size variability and model generalization.
Entropy (Basel, Switzerland)
May 28, 2024
Hartmut Neven, Adam Zalcman, Peter Read et al.
Conscious experience may emerge from quantum mechanical superpositions, a groundbreaking idea that suggests the structure of these superpositions shapes our experiences. This theory posits that quantum entanglement resolves the binding problem, creating a unified phenomenal experience. In a proposed series of experiments involving brain organoids and xenon anesthesia, the aim is to explore these connections further. With a focus on brain-computer interfaces, this approach could potentially enhance human consciousness, offering innovative avenues for understanding the physical substrate of consciousness.
PloS one
January 1, 2026
Matilda Gibbons, Ethan G McBride, Raghuram Holenarasipura Venkatasubbaiah et al.
An adversarial collaboration will test competing predictions from Global Neuronal Workspace Theory and Integrated Information Theory about the neural correlates of consciousness. Non-human primates and mice will perform a go-nogo task with supra-threshold visual and auditory stimuli while neural activity is recorded from multiple cortical areas using Neuropixels electrodes. To causally test timing and location predictions, prefrontal cortex activity will be manipulated via electrical stimulation in primates or optogenetic silencing in mice. The protocol details experimental design, analyses, divergent predictions, and anticipated outcomes.
bioRxiv Preprint Server
May 15, 2024
Dana Mastrovito, Yuhan Helena Liu, Lukasz Kusmierz et al.
preprint
The critical coupling strength that separates chaotic from ordered dynamics in recurrent neural networks also differentiates two learning strategies: networks initialized with low coupling learn rich representations, while those with larger variance learn lazier solutions. Training moves both stable and chaotic networks closer to the edge of chaos. Biologically realistic connectivity fosters stability across a wide range of variances. The transition to chaos is reflected in the perturbational complexity index (PCIst), a measure that clinically discriminates levels of consciousness. Networks with high PCIst exhibit stable dynamics and rich learning, suggesting a consciousness prior may promote rich learning. The results indicate a relationship between critical dynamics, learning regimes, and complexity-based measures of consciousness.
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.
Trends in Cognitive Sciences
June 22, 2021
C. Dembski, Christof Koch, Michael A. Pitts
The P3b brain wave is not a reliable marker of conscious perception, as many experiments have failed to observe it during conscious experience. In contrast, the visual and auditory awareness negativity (VAN and AAN) have not been dissociated from consciousness, and a similar signal correlates with tactile consciousness. These awareness negativities are likely generated in sensory cortices and can be maximal contralateral to the stimulus, suggesting a generalized perceptual awareness negativity (PAN) that marks the onset of sensory consciousness.
Science
May 28, 2021
L. Melloni, L. Mudrik, Michael A. Pitts et al.
Consciousness remains a hard problem: why does neural activity produce subjective experience, like the taste of chocolate or the feeling of a caress? Understanding this has medical and ethical implications, from assessing consciousness after brain injury to deciding whether nonhuman animals, fetuses, organoids, or advanced machines are conscious. A comprehensive theory is needed to determine which systems experience anything and to define ethical boundaries. An adversarial collaboration championing open science aims to test whether major current theories hold up.
arXiv Preprint Archive
May 27, 2014
Giulio Tononi, Christof Koch
Integrated Information Theory (IIT) starts from five axioms about conscious experience—existence, composition, information, integration, and exclusion—to derive physical postulates that specify which systems can be conscious and what their experience is like. IIT provides a calculus to measure both the quantity and quality of experience, explains clinical and laboratory findings, and makes testable predictions. It holds that consciousness is graded, common among biological organisms, and present even in some simple systems, but not in everything: groups of individuals or feedforward networks lack it. Crucially, IIT implies that digital computers, even those that perfectly simulate human behavior or brain function, would experience next to nothing, contradicting functionalist views.