Neural correlates of consciousness: progress and problems
Nature reviews. Neuroscience April 20, 2016 Christof Koch, Marcello Massimini, Mélanie Boly et al. 1,654 citations
The text does not provide any content to summarize.
Marcello Massimini
Department of Biomedical and Clinical Sciences, University of Milan, Via Giovanni Battista Grassi 74, 20157 Milan, Italy; Istituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, Via Alfonso Capecelatro 66, 20148 Milan, Italy.
10 papers in the library · 2,496 citations · publishing 2016-2025
Papers
The spectral exponent of the resting EEG indexes the presence of consciousness during unresponsiveness induced by propofol, xenon, and ketamine
NeuroImage January 11, 2019 Michele Colombo, Martino Napolitani, Mélanie Boly et al. 359 citations
During anesthesia, people may still be conscious even though they do not respond. A marker of consciousness based on the decay rate of the power spectral density (PSD) of resting EEG—measured by the spectral exponent β—was tested in healthy participants under xenon, propofol, or ketamine anesthesia (n=5 per group). Delayed reports indicated whether consciousness was present or absent. Xenon and propofol, which abolish consciousness, caused a steeper PSD decay (more negative β) compared to wakefulness. Ketamine, which preserves consciousness, showed a PSD decay similar to wakefulness overall but a flattening in high frequencies (20–40 Hz). The spectral exponent correlated strongly with the Perturbational Complexity Index (PCI), supporting its use as a marker of consciousness.
Consciousness and complexity: a consilience of evidence
Neuroscience of Consciousness January 1, 2021 Simone Sarasso, Adenauer G. Casali, Silvia Casarotto et al. 183 citations
A growing body of empirical studies has identified complexity-related measures as reliable markers of consciousness across conditions including sleep, anesthesia, hallucinatory states, coma, and related disorders. These measures were proposed independently by researchers working within different frameworks and using diverse methods. This paper systematically reviews that literature, identifies a common denominator among the measures, and traces it to theoretical principles and predictions made over 20 years ago. The authors highlight a consistent trajectory across two decades of consciousness research and offer a provisional taxonomy of the existing work. They argue that this convergence provides a solid foundation for designing future experiments and advancing the field.
Quantifying arousal and awareness in altered states of consciousness using interpretable deep learning
Nature Communications February 25, 2022 Minji Lee, Leandro Sanz, Alice Barra et al. 120 citations
A deep-learning-based explainable consciousness indicator (ECI) uses EEG responses to transcranial magnetic stimulation and resting-state EEG to separately quantify arousal and awareness. Tested during sleep (n=6), general anesthesia (n=16), and severe brain injury (n=34), ECI distinguishes states such as ketamine-induced anesthesia and rapid eye movement sleep, which combine low arousal with high awareness. Parietal brain regions are most relevant for these measurements. The indicator offers a way to disentangle the two components of consciousness across physiological, pharmacological, and pathological conditions.
An integrative, multiscale view on neural theories of consciousness.
Neuron May 15, 2024 Johan F Storm, P Christiaan Klink, Jaan Aru et al. 108 citations
Consciousness may be explained by multiple, partly compatible theories rather than a single winner. A group of scientists representing different theories argue that various accounts often address different aspects or mechanistic levels of conscious experience, so they do not necessarily contradict each other. Instead, several theories may converge on fundamental neuronal mechanisms and be complementary, allowing multiple perspectives to simultaneously advance understanding. The authors advocate for unifying, integration-oriented approaches that combine valuable elements from diverse theories, an approach that has so far been largely neglected.
Are the neural correlates of consciousness in the front or in the back of the cerebral cortex? Clinical and neuroimaging evidence
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.
Conscious tactile perception entails distinct neural dynamics within somatosensory areas.
Current biology : CB June 9, 2025 Davide Albertini, Maria Del Vecchio, Ivana Sartori et al. 9 citations
Conscious perception of simple touch depends on sustained neural activity in higher-order somatosensory regions, specifically the posterior perisylvian areas. Using human intracortical recordings, tonic responses in these regions showed all-or-nothing patterns at the sensory threshold, remained unchanged whether or not participants reported the stimulus, and most clearly distinguished perceived from non-perceived stimuli. These dynamics may serve as an organizational principle of somatosensory awareness.
Hemispherotomy leads to persistent sleep-like slow waves in the isolated cortex of awake humans.
PLoS biology October 1, 2025 Michele Angelo Colombo, Jacopo Favaro, Ezequiel Mikulan et al. 7 citations
After hemispherotomy surgery for epilepsy, which disconnects an entire brain hemisphere, the isolated cortex shows brainwave patterns typical of deep sleep or anesthesia, not wakefulness. In 10 pediatric patients, EEG recordings revealed prominent slow oscillations and a steeper spectral decay in the disconnected hemisphere, while the connected hemisphere maintained normal waking patterns. These sleep-like patterns persisted years after surgery, suggesting the isolated cortex likely lacks awareness.
Thermodynamics of consciousness: A non-invasive perturbational framework
bioRxiv Preprint Server December 9, 2025 Tomas Berjaga-Buisan, Juan Manuel Monti, Martina Cortada et al. preprint
A non-invasive framework using generative whole-brain models of non-equilibrium dynamics reveals that violations of the Fluctuation-Dissipation Theorem (FDT) in spontaneous brain signals are reduced in unresponsive disorders of consciousness and anesthesia compared to conscious states, mirroring patterns seen with the Perturbational Complexity Index (PCI). This links PCI to fundamental physics principles and offers new objective, model-based tools for assessing consciousness loss and recovery.
Spatiotemporal brain complexity quantifies consciousness outside of perturbation paradigms
bioRxiv Preprint Server April 18, 2023 Martin Breyton, Jan Fousek, Giovanni Rabuffo et al. preprint
Consciousness depends on the brain's ability to produce complex, variable patterns of activity after a perturbation, but measuring this directly is difficult. Using a whole-brain model, researchers found that such complexity only arises when spontaneous brain activity is highly fluid—meaning functional networks reorganize extensively. This fluid regime can be captured by a small set of dynamical systems metrics, which predict the effects of consciousness-altering drugs like Xenon, Propofol, and Ketamine. These predictions were validated in 15 subjects at different consciousness levels, showing agreement with established perturbational complexity measures but using a simpler, more accessible paradigm. The findings point to complexity properties underlying consciousness.