The question of AI consciousness is one of the most urgent pre-emptive problems in philosophy and computer science, yet progress is hampered by a cacophony of competing theories that often talk past each other. Separating the hard problem from the mapping problem allows the deepest metaphysical disagreements to be set aside: granting that experience supervenes on a system's organisation, the...
Brain ResearchSeptember 7, 2026Eleni Kroupi, Helena Araujo, Cas Oosterveld et al.
N,N-Dimethyltryptamine (DMT), a potent serotonin-2A receptor agonist, elicits intense psychedelic experiences and has become a focus of interest in neuroscience and mental health research. While EEG studies of psychedelics typically report reduced alpha power, increased delta power, and enhanced signal complexity-primarily assessed using Lempel-Ziv complexity (LZc)-less is known about DMT's...
We propose three entangled characteristics that explain the functional properties of consciousness: Emotion, quantum-like interference and hierarchy. The argument proceeds from thermodynamic first principles. Biological systems must stay far from equilibrium at minimal energy cost, and emotion is one of evolution’s heuristic solutions to this constraint. Valenced summary statistics compress the...
Abstract Background The Pivotal Mental States (PiMS) construct posits that psychedelics and other stress-inducing practices, such as fasting and hypoxia, can evoke transformative mental states through increased serotonin receptor activation in the brain. These states are associated with enhanced cognitive flexibility, accelerated associative learning, and psychological insights that may...
Consciousness spans a range of phenomenological experiences, from effortless immersion to disengaged monotony, yet how such phenomenology emerges from brain activity is not well understood. Flow, a phenomenological experience frequently elicited by interactive media, has drawn attention for its links to performance and wellbeing, but existing neural accounts rely on single-region or...
Consciousness science is fragmented, and empirical investigations are confined within each theory of consciousness’ (TOC) framework. Proliferating ToCs accumulate anomalies without progress, operating orthogonally. The principle of recurrency – functional and architectural – offers a unifying, mechanistic scaffold for consciousness to arise. We show that all theories tacitly invoke feedback...
First-line dictionary definitions of ‘plasticity’ describe it as the ability (of a thing) to be shaped or molded; we call this ‘plasticity proper’. In neuroscience, however, ‘neural plasticity’ or ‘neuroplasticity’ is defined as an induced change in brain function or structure. These two plasticities are not the same. Several (but not all) popular biomarkers of neuroplasticity index part of an...
Psychedelics have robust effects on acute brain function and long-term behavior but whether they also cause enduring functional and anatomical brain changes is largely unknown. In an exploratory, placebo-controlled, within-subjects, electroencephalography (EEG), and magnetic resonance imaging (MRI) study in 28 healthy, entirely psychedelic-naive participants, anatomical and functional brain...
Recent advances have shown that the complexity of neural signals tracks global states of consciousness, such as wakefulness versus sleep. However, it is still unclear to what extent neural complexity reflects fine-grained changes in conscious content within the same global state. Here, we investigate how the complexity of brain signals is affected by increased perceptual clarity of a stimulus....
The integrated information theory of consciousness (IIT) is uniquely ambitious in proposing a mathematical formula, derived from apparently fundamental properties of conscious experience, to describe the quantity and quality of consciousness for any physical system that possesses it. IIT has generated considerable debate, which has engendered some misunderstandings and misrepresentations. Here...
AbstractBackgroundResearch has shown that psychedelics may have therapeutic potential in treating mental disorders like depression and anxiety. However, the mechanisms and actions underlying their effects are still not fully understood. Similarly, while the significance of mindset and setting in shaping psychedelic experiences and therapeutic outcomes is well established, information about the...
The Relaxed Beliefs Under pSychedelics (REBUS) model proposes that serotonergic psychedelics decrease the precision weighting of neurobiologically-encoded beliefs. We conducted a preliminary examination of two psychological assumptions of REBUS: (a) psychedelics foster acute relaxation and post-acute revision of confidence in mental-health-relevant beliefs; which (b) facilitate positive...
Recent years have seen growing interest in the use of metrics inspired by complexity science for the study of consciousness. Work in this field has shown remarkable results in discerning conscious from unconscious states, and in characterizing states of altered conscious experience following psychedelic intake as involving enhanced complexity. Here, we study the relationship between complexity...
Non-ordinary states of consciousness induced by psychedelics can be accompanied by so-called "peak experiences," characterized at the emotional level by their intensity and positive valence. These experiences are strong predictors of positive outcomes following psychedelic-assisted therapy, and it is therefore important to better understand their biology. Despite growing evidence that the...
How is the information-processing architecture of the human brain organised, and how does its organisation support consciousness? Here, we combine network science and a rigorous information-theoretic notion of synergy to delineate a 'synergistic global workspace', comprising gateway regions that gather synergistic information from specialised modules across the human brain. This information is...
To investigate the association between pre-trial expectancy, suggestibility, and response to treatment in a trial of escitalopram and investigational drug, COMP360, psilocybin, in the treatment of major depressive disorder (ClinicalTrials.gov registration: NCT03429075). We used data (n = 55) from our recent double-blind, parallel-group, randomized head-to-head comparison trial of escitalopram...
Disentangling how cognitive functions emerge from the interplay of brain dynamics and network architecture is among the major challenges that neuroscientists face. Pharmacological and pathological perturbations of consciousness provide a lens to investigate these complex challenges. Here, we review how recent advances about consciousness and the brain's functional organisation have been driven...
Background: Reference to an intrinsic healing mechanism or an ‘inner healer’ is commonplace amongst psychedelic drug-using cultures. The ‘inner healer’ refers to the belief that psychedelic compounds, plants or concoctions have an intrinsically regenerative action on the mind and brain, analogous to intrinsic healing mechanisms within the physical body, for example, after sickness or injury....
Background: There is growing evidence for the therapeutic effects of the psychedelic drug psilocybin for major depression. However, due to the lack of safety data on combining psilocybin with selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) and concerns that there may be a negative interaction on efficacy, participants enrolling in...
Recent findings have shown that psychedelics reliably enhance brain entropy (understood as neural signal diversity), and this effect has been associated with both acute and long-term psychological outcomes, such as personality changes. These findings are particularly intriguing, given that a decrease of brain entropy is a robust indicator of loss of consciousness (e.g., from wakefulness to...
N,N-Dimethyltryptamine (DMT) is a serotonergic psychedelic that induces a rapid and transient altered state of consciousness when inhaled or injected via bolus administration. Its marked and novel subjective effects make DMT a powerful tool for the neuroscientific study of consciousness and preliminary results show its potential role in treating mental health conditions. In a within-subjects,...
Integrating independent but converging lines of research on brain function and neurodevelopment across scales, this article proposes that serotonin 2A receptor (5-HT2AR) signalling is an evolutionary and developmental driver and potent modulator of the macroscale functional organization of the human cerebral cortex. A wealth of evidence indicates that the anatomical and functional organization...
A growing body of work shows that autonomic signals provide a privileged evidence-stream to capture various aspects of subjective and neural states. This work investigates the potential for autonomic markers to track the effects of psychedelics — potent psychoactive drugs with important scientific and clinical value. For this purpose, we introduce a novel Bayesian framework to estimate the...
Healthy brain functioning depends on balancing stable integration between brain areas for effective coordinated functioning, with bursts of desynchronisation to allow subsystems to reconfigure and express functional specialisation. Metastability, a concept originated in statistical physics and dynamical systems theory, has been proposed as a key signature that characterises this balance....
Recent years have seen a growing interest in the use of measures inspired by complexity science for the study of consciousness. The work done in this field has shown remarkable results in discerning conscious from unconscious states, and in characterizing states of altered conscious experience following intake of psychedelic substances as involving enhanced complexity. However, the relationship...