Cell Reports
August 1, 2026
Rui Dai, Hyunwoo Jang, A. Hudetz et al.
Understanding the relationship of conscious states to large-scale brain dynamics remains a central challenge in neuroscience. Here, diverse pharmacological and physiological perturbations-including psychedelics, sleep, and propofol sedation-are used to examine integration-segregation organization of brain networks across altered states of consciousness in humans using functional MRI. Across...
bioRxiv : the preprint server for biology
June 1, 2026
Panagiotis Fotiadis, Hyunwoo Jang, Rui Dai et al.
Brain waves are ubiquitous phenomena of human brain activity. As they propagate, they coordinate neural communication, shaping conscious perception. Understanding how brain waves unfold across space and time is thus critical for uncovering the neural mechanisms that support and suppress consciousness. Here, we analyzed data from the Human Connectome Project alongside multiple independent human...
Scientific Data
January 9, 2026
Zirui Huang, Vijay Tarnal, Panagiotis Fotiadis et al.
Anesthesia has revolutionized surgical practice and offers a controlled model to study the neurobiology of consciousness. Functional magnetic resonance imaging (fMRI) studies have shown that anesthesia primarily disrupts connectivity across association cortices, suggesting that impaired integration between higher-order brain regions underlies unconsciousness. However, traditional fMRI paradigms...
bioRxiv
November 26, 2025
Rui Dai, Rodrigo Cofré, Christopher Timmermann et al.
preprint
The mechanism of psychedelic drug action is a dynamic area of neuroscience, with two major lines of investigation: (1) laboratory studies at the molecular and cellular level, and (2) human neuroimaging studies of functional brain networks. Despite considerable progress, there remains insufficient understanding of the link between molecular/cellular substrates of psychedelics and the whole-brain...
bioRxiv (Cold Spring Harbor Laboratory)
October 14, 2025
Nicholas Kolbman, Amanda Nelson, Rachel Summerfield et al.
1 citation
preprint
Abstract Background and Purpose Given the increase in recreational psychedelic use and ongoing efforts to explore psychedelics as therapeutic agents for mental health disorders, there is an urgent need to understand the effect of psychedelics such as psilocybin and N,N-dimethyltryptamine (DMT) on sleep-wake states, which share a bidirectional relationship with mental health. Here, we...
Cambridge quarterly of healthcare ethics : CQ : the international journal of healthcare ethics committees
January 3, 2025
Matthew Owen, Darren Hight, Anthony G. Hudetz
Studies have shown that some covertly conscious brain-injured patients, who are behaviorally unresponsive, can reply to simple questions via neuronal responses. Given the possibility of such neuronal responses, Andrew Peterson et al. have argued that there is warrant for some covertly conscious patients being included in low-stakes medical decisions using neuronal responses, which could protect...
Nature Communications
October 24, 2024
Hyunwoo Jang, George A. Mashour, Anthony G. Hudetz et al.
Consciousness requires a dynamic balance of integration and segregation in brain networks. We report an fMRI-based metric, the integration-segregation difference (ISD), which captures two key network properties: network efficiency (integration) and clustering (segregation). With this metric, we quantify brain state transitions from conscious wakefulness to unresponsiveness induced by the...
bioRxiv : the preprint server for biology
October 23, 2024
Rui Dai, Hyunwoo Jang, Anthony G. Hudetz et al.
1 citation
preprint
Understanding neural mechanisms of consciousness remains a challenging question in neuroscience. A central debate in the field concerns whether consciousness arises from global interactions that involve multiple brain regions or focal neural activity, such as in sensory cortex. Additionally, global theories diverge between the Global Neuronal Workspace (GNW) hypothesis, which emphasizes frontal...
Nature Communications
September 9, 2024
Zirui Huang, George A. Mashour, Anthony G. Hudetz
23 citations
Research into the role of thalamocortical circuits in anesthesia-induced unconsciousness is difficult due to anatomical and functional complexity. Prior neuroimaging studies have examined either the thalamus as a whole or focused on specific subregions, overlooking the distinct neuronal subtypes like core and matrix cells. We conducted a study of heathy volunteers and functional magnetic...
Brain Sciences
August 30, 2024
Hyunwoo Jang, Rui Dai, George A. Mashour et al.
Accurate and generalizable classification of brain states is essential for understanding their neural underpinnings and improving clinical diagnostics. Traditionally, functional connectivity patterns and graph-theoretic metrics have been utilized. However, cortical gradient features, which reflect global brain organization, offer a complementary approach. We hypothesized that a machine learning...
Journal of Consciousness Studies
August 1, 2024
Anthony G. Hudetz
Whether consciousness is unidimensional with states defined along a single scale or it consists of multiple fundamental dimensions has been debated. Clinical assessment of consciousness distinguishes the content of consciousness (awareness) and the level of consciousness (wakefulness or arousal), which conflates firstperson phenomenal properties with third-person observable properties. The...
bioRxiv
April 15, 2024
Hyunwoo Jang, George A. Mashour, Anthony G. Hudetz et al.
preprint
Consciousness requires a dynamic balance of integration and segregation in functional brain networks. An optimal integration-segregation balance depends on two key aspects of functional connectivity: global efficiency (i.e., integration) and clustering (i.e., segregation). We developed a new fMRI-based measure, termed the integration-segregation difference (ISD), which captures both aspects. We...
Frontiers in Neuroscience
2024
Anthony G. Hudetz
Complex neuronal interactions underlie cortical information processing that can be compromised in altered states of consciousness. Here intracortical microstimulation was applied to investigate anesthetic state-dependent effective connectivity of neurons in rat visual cortex in vivo. Extracellular activity was recorded at 32 sites in layers 5/6 while stimulating with charge-balanced discrete...
Commun Biol
December 19, 2023
Rui Dai, Zirui Huang, Tony E. Larkin et al.
7 citations
Psychedelic concentrations of nitrous oxide reduce functional differentiation in frontoparietal and somatomotor cortical networks.
Cambridge quarterly of healthcare ethics : CQ : the international journal of healthcare ethics committees
October 18, 2023
Matthew Owen, Zirui Huang, Catherine Duclos et al.
Organoids and specifically human cerebral organoids (HCOs) are one of the most relevant novelties in the field of biomedical research. Grown either from embryonic or induced pluripotent stem cells, HCOs can be used as in vitro three-dimensional models, mimicking the developmental process and organization of the developing human brain. Based on that, and despite their current limitations, it...
Neuroimage
June 1, 2023
Rui Dai, Tony E. Larkin, Zirui Huang et al.
49 citations
The neurobiology of the psychedelic experience is not fully understood. Identifying common brain network changes induced by both classical (i.e., acting at the 5-HT2 receptor) and non-classical psychedelics would provide mechanistic insight into state-specific characteristics. We analyzed whole-brain functional connectivity based on resting-state fMRI data in humans, acquired before and during...
Nature Communications
January 5, 2023
Zirui Huang, George A. Mashour, Anthony G. Hudetz
Consciousness is a multidimensional phenomenon, but key dimensions such as awareness and wakefulness have been described conceptually rather than neurobiologically. We hypothesize that dimensions of consciousness are encoded in multiple neurofunctional dimensions of the brain. We analyze cortical gradients, which are continua of the brain’s overarching functional geometry, to characterize these...
Cell Reports
May 1, 2021
Zirui Huang, Vijay Tarnal, Phillip E. Vlisides et al.
119 citations
Conscious access to sensory information is likely gated at an intermediate site between primary sensory and transmodal association cortices, but the structure responsible remains unknown. We perform functional neuroimaging to determine the neural correlates of conscious access using a volitional mental imagery task, a report paradigm not confounded by motor behavior. Titrating propofol to loss...
Neuroimage
May 1, 2021
Pengmin Qin, Xuehai Wu, Changwei W Wu et al.
51 citations
Consciousness is a mental characteristic of the human mind, whose exact neural features remain unclear. We aimed to identify the critical nodes within the brain's global functional network that support consciousness. To that end, we collected a large fMRI resting state dataset with subjects in at least one of the following three consciousness states: preserved (including the healthy awake...
Science Advances
March 1, 2020
Zirui Huang, Jun Zhang, Jinsong Wu et al.
Neuroimaging suggests that human consciousness relies on frequent access to default mode and dorsal attention brain networks. The ongoing stream of human consciousness relies on two distinct cortical systems, the default mode network and the dorsal attention network, which alternate their activity in an anticorrelated manner. We examined how the two systems are regulated in the conscious brain...
Entropy
July 10, 2018
Heonsoo Lee, Zirui Huang, Xiaolin Liu et al.
Theoretical consideration predicts that the alteration of local and shared information in the brain is a key element in the mechanism of anesthetic-induced unconsciousness. Ordinal pattern analysis, such as permutation entropy (PE) and symbolic mutual information (SMI), have been successful in quantifying local and shared information in neurophysiological data; however, they have been rarely...
Frontiers in Human Neuroscience
February 16, 2018
Hyoungkyu Kim, Anthony G. Hudetz, Joseph W Y Lee et al.
The integrated information theory (IIT) proposes a quantitative measure, denoted as Φ, of the amount of integrated information in a physical system, which is postulated to have an identity relationship with consciousness. IIT predicts that the value of Φ estimated from brain activities represents the level of consciousness across phylogeny and functional states. Practical limitations, such as...
Frontiers in Neural Circuits
June 20, 2017
George A. Mashour, Anthony G. Hudetz
136 citations
There has been controversy regarding the precise mechanisms of anesthetic-induced unconsciousness, with two salient approaches that have emerged within systems neuroscience. One prominent approach is the "bottom up" paradigm, which argues that anesthetics suppress consciousness by modulating sleep-wake nuclei and neural circuits in the brainstem and diencephalon that have evolved to control...
Anesthesia & Analgesia
June 23, 2016
Anthony G. Hudetz, George A. Mashour
128 citations
A quest for a systems-level neuroscientific basis of anesthetic-induced loss and return of consciousness has been in the forefront of research for the past 2 decades. Recent advances toward the discovery of underlying mechanisms have been achieved using experimental electrophysiology, multichannel electroencephalography, magnetoencephalography, and functional magnetic resonance imaging. By the...
Frontiers in Psychology
September 16, 2014
Talis eBachmann, Anthony G. Hudetz
Research on neural correlates of consciousness has been conducted and carried out mostly from within two relatively autonomous paradigmatic traditions – studying the specific contents of conscious experience and their brain-process correlates and studying the level of consciousness. In the present paper we offer a theoretical integration suggesting that an emphasis has to be put on...