Neuroscience and Biobehavioral Reviews
November 19, 2025
Daniel K. Freeman, Brian Odegaard, Seung-Schik Yoo et al.
Transcranial focused ultrasound (tFUS) can stimulate the human brain non-invasively with millimeter-scale precision, targeting both cortical and deep structures. This new tool offers a potential breakthrough for studying the neural correlates of conscious perception, overcoming the coarse spatial resolution and limited depth of traditional electrical or magnetic stimulation. Because tFUS requires extensive preparation and regulatory approvals, careful experimental planning is essential. The authors provide a roadmap for using tFUS in humans to explore the neural substrate of conscious perception.
Neuroscience and Biobehavioral Reviews
November 19, 2025
Inbal Algom, Oren Shriki
Theories of consciousness offer valuable insights but lack a unifying mechanistic framework. The ConCrit hypothesis proposes that consciousness arises when neural networks operate near a critical transition point—a state of heightened sensitivity and complexity. Near-critical systems enhance the richness of internal representations and sensitivity to the system's own state, making conscious experience more likely. As the brain deviates from this critical regime, consciousness may diminish. This review examines critical brain dynamics, their theoretical and empirical links to consciousness, and outlines predictions for testing the framework.
Neuroscience and Biobehavioral Reviews
July 1, 2022
Drummond E-Wen Mcculloch, Gitte Moos Knudsen, Frederick Streeter Barrett et al.
A large group of psychedelic imaging researchers reviewed 42 articles from 17 unique studies that used resting-state functional magnetic resonance imaging (rs-fMRI) to examine psychedelic effects. They found that nearly all studies varied in data processing and analysis methods, two datasets underpin over half of the published literature, and key outcome terms are used ambiguously. The authors recommend guidelines to improve consistency and replicability in future research, arguing that the field must balance novel methods with standardized approaches to reliably understand the neural mechanisms of psychedelics.
Neuroscience and Biobehavioral Reviews
September 1, 2026
Isabella Goodwin, Dominic Oliver, Edward Chesney et al.
A meta-analysis of 41 double-blind, placebo-controlled experiments involving 1,020 infrequent cannabis users found that acute THC administration increases feelings of high, anxiety, and tiredness, while decreasing alertness and contentedness, with no effect on calmness. Inhaled THC dose-dependently increased high and contentedness but decreased calmness, with greater consistency in high and contentedness at higher doses. On a 100-point scale, inhaling 5 mg THC increased high by 34.3 points, anxiety by 14.4, tiredness by 26.3, and calmness by 4.5, while decreasing alertness by 40.2 and contentedness by 71.0. Oral THC showed no significant subjective effects, though higher oral doses produced more consistent alertness. These findings can inform public health guidance on expected THC effects.
Neuroscience and Biobehavioral Reviews
September 1, 2026
Jeremy I Skipper, Daniel R Lametti, David W Green
Aberrations in inner speech are linked to psychotic symptoms such as thought insertion and auditory verbal hallucinations, which may arise from failures in prediction and source monitoring. Normally, efference copies of speech motor commands suppress auditory responses to self-generated input; if suppression malfunctions, predicted auditory input becomes perceptually salient. Impaired self-monitoring regions (e.g., anterior cingulate cortex) may cause inner speech to be misattributed as external. Neuroimaging meta-analyses of neurotypical participants and psychosis spectrum participants showed increased activity in motor-related regions (e.g., ventral premotor cortices) and decreased grey matter in auditory cortices and ACC. These regions form distinct, inversely coupled audiomotor networks, supporting the proposal that psychotic symptoms derive from hyperactivation in inner speech regions producing insufficiently suppressed efference copy signals.
Neuroscience and Biobehavioral Reviews
August 1, 2026
Stéphane Mathis, Gwendal Le Masson
Whether consciousness persists after decapitation has been debated for over two centuries, from guillotine-era anecdotes to modern neuroscience. This review synthesizes historical controversies—facial movements in severed heads and early galvanism experiments—with contemporary neurophysiological evidence. The authors trace the evolution of hypotheses from philosophical speculation to EEG-based debates and finally to neuroimaging of the 'wave of death,' an irreversible neuronal depolarization occurring approximately 27 seconds after decapitation. By integrating comparative studies across rats, lambs, and humans, and drawing clinical parallels with brain death and traumatic brain injury, the review highlights neurophysiological mechanisms and ethical implications. It provides a critical perspective on the neural correlates of consciousness and the boundaries between life and death.
Neuroscience and Biobehavioral Reviews
August 1, 2026
Fabrizio Ascone, Diletta Giangiacomo, Viviana Trezza
A review of preclinical studies finds that classic psychedelics affect behavioral domains overlapping with autism spectrum disorder (ASD), including social interaction, communication, repetitive behaviors, anxiety-like traits, and cognitive function. The neurobiological mechanisms involve serotonergic signaling, glutamatergic neurotransmission, neuroinflammatory processes, BDNF/TrkB pathways, and oxytocinergic and dopaminergic modulation. Mechanistic convergence with neurobiological alterations implicated in ASD is identified, but significant gaps constrain interpretation, including a scarcity of studies in established animal models of ASD, reliance on simplified behavioral assays, and uncertainty about how ASD-specific circuit alterations may influence responses to psychedelics.
Neuroscience and Biobehavioral Reviews
July 13, 2026
Nelson Cowan, Leonel A Gomez
Scientific theories of human consciousness differ in how much of the brain they require to support conscious experience. Most current theories assume a big-tent, integrated neural substrate that must combine many types of information—sensations, perceptions, thoughts, and emotions. This paper argues that small-tent theories, which propose a more localized neural basis, remain plausible. In a small-tent account, multiple brain processes selectively funnel information into a critical conscious area, but no single input is necessary. The embedded-processes theory exemplifies this, positing that the left and right intraparietal sulcus and their connection form a capacity-limited focus of attention synonymous with consciousness, embedded within a larger field of unconscious memory activation. The paper explores what evidence could determine where on the big-tent to small-tent continuum consciousness falls.
Neuroscience and Biobehavioral Reviews
July 1, 2026
Caitlin Baten, Arielle S Keller, Chris H. Miller et al.
A quantitative whole-brain meta-analysis of 34 fMRI studies involving 700 individuals examined four meditation practices: focused attention, open monitoring, mantra, and loving-kindness. Consistent activation across practices appeared in the rolandic operculum, insula, superior temporal gyrus, supplementary motor area, and hippocampus. Functional decoding linked meditation engagement to self-monitoring, reappraisal, motivation, experience, and awareness states. Meta-analytic comparisons revealed distinct neural patterns unique to each practice. These findings provide the most robust scientific characterization of the neural mechanisms of meditative states to date, setting the stage for future research into advanced meditation and clearer phenomenological characterization.
Neuroscience and Biobehavioral Reviews
June 1, 2026
Agustin Ibanez, Nick Roth, Aaron Colverson et al.
Metaphors have long shaped how scientists conceptualize the mind and brain, from early analogies like hydraulic systems to the modern computer metaphor. This paper proposes music as a new scientific metaphor for understanding brain dynamics and cognitive functions. Unlike static metaphors, music emphasizes continuous adaptation, context-dependence, cultural embedding, and simultaneous engagement with multiple layers of meaning. The authors argue that music's hierarchical structure, temporal complexity, and capacity to integrate multiple processes parallel key features of brain architecture and cognition. Drawing on research in neural oscillations, plasticity, predictive coding, and emotional processing, they illustrate how a musical paradigm can capture the rich interplay of mind and brain across large-scale dynamics, development, consciousness, and affect.
Neuroscience and Biobehavioral Reviews
May 1, 2026
Esmaeel G Gojani, Houman Farzin, Robert J Sutherland et al.
Alzheimer's disease involves amyloid-β accumulation, tau pathology, synaptic dysfunction, and neuroinflammation, driving progressive memory loss and cognitive decline. Epigenetic dysregulation is increasingly recognized as contributing to these processes by altering gene expression. Serotonergic psychedelics, acting as agonists of the serotonin 2A receptor, promote neuroplasticity and induce sustained transcriptional changes in the brain. Preclinical studies suggest these compounds can modulate epigenetic mechanisms, including histone modifications and DNA methylation. This review proposes that targeted engagement of 5-HT2A receptors may help counteract epigenetic abnormalities that contribute to Alzheimer's disease pathogenesis.
Neuroscience and Biobehavioral Reviews
January 1, 2026
Charlène Aubinet, Olivia Gosseries, Steve Majerus
Language and consciousness interact in complex ways, with high-level semantic and sentence integration requiring conscious processing, while lower-level phonetic, phonological, and lexico-semantic processes can function without consciousness. Evidence from neuroimaging, cognitive, and neuropsychological studies shows parallel recovery trajectories between aspects of language and states of consciousness, and language processing may influence consciousness content or precede the reemergence of consciousness. Associations between language processing and higher-order conscious thought exist, but observed links may reflect broader integration disruptions rather than language-specific mechanisms. Theoretical implications and methodological challenges, especially regarding causal direction, are discussed.
Neuroscience and Biobehavioral Reviews
December 1, 2025
Álex Escolà-Gascón, Kenneth Drinkwater, Andrew Denovan et al.
A new metric called the Attribution Consciousness Index (ACI) estimates the likelihood that neural activity supports conscious processing by balancing measures of dynamic information and complexity. Using brain simulations and artificial neural networks, the ACI follows a log-normal distribution, enabling robust thresholding: values above 10 correspond to over 90% probability of conscious emergence. The framework also applies to artificial systems, explaining 38.4% of variance between biological and AI-derived patterns. While not measuring subjective experience, the ACI predicts when neural or artificial conditions are poised to sustain consciousness, with potential applications in disorders of consciousness, anesthesia monitoring, neurorehabilitation, and evaluating neuroprosthetics, generative AI, and robotics.
Neuroscience and Biobehavioral Reviews
July 1, 2025
Rumi Murayama, Yi Cai, Hiroyuki Nakamura et al.
Loss of myelin sheaths around neuronal axons is increasingly recognized as a key factor in a broad range of psychiatric and neurological disorders, including schizophrenia, major depressive disorder, bipolar disorder, post-traumatic stress disorder, autism spectrum disorder, substance use disorders, Alzheimer's disease, Parkinson's disease, and multiple sclerosis. This review examines core mechanisms driving demyelination, its clinical impact, and emerging therapeutic strategies. Key contributors include genetic predisposition, environmental triggers, immune dysregulation, neuroinflammation, and alterations in the gut-brain axis mediated by the vagus nerve.
Neuroscience and Biobehavioral Reviews
December 1, 2024
Pedro T Palhares, Madalina I Sas, Óscar F. Gonçalves
Music reliably alters mental and physical states, making it a natural tool for studying consciousness. This narrative review assesses how empirical research in music psychology and neuroscience has contributed to understanding non-ordinary states of consciousness, including absorption, mind wandering, and creative thought. The authors argue that music's unique capacity to induce such states offers special insight into consciousness, yet music-related studies remain marginalized in the broader field. They critically evaluate key contributions and identify how music's distinctive aspects can shape future investigations. The review concludes that integrating music into consciousness research is essential and highlights promising interdisciplinary avenues for exploration.
Neuroscience and Biobehavioral Reviews
August 1, 2024
Serena Scarpelli, Valentina Alfonsi, Luigi De Gennaro et al.
Pregnancy is linked to changes in sleep and dreaming. A systematic review of 17 studies found that pregnant women tend to report more dreams and nightmares, and high dream recall is associated with poor sleep quality. Most dream content relates to pregnancy, reflecting waking concerns. Dreaming may help women psychologically prepare for childbirth and develop coping strategies for life after delivery.
Neuroscience and Biobehavioral Reviews
August 1, 2024
K. Abellaneda-Pérez, Ruby M. Potash, Á. Pascual-Leone et al.
Non-invasive brain stimulation (NIBS) can help researchers investigate the neural mechanisms underlying meditation's beneficial effects on well-being and consciousness. Prior research has mainly targeted frontal and parietal cortices, suggesting NIBS might boost meditation's behavioral and neural effects. NIBS has also revealed distinct neural signatures in long-term meditators. However, methodological variations across studies make definitive interpretation of results challenging. Future work should focus on core substrates of meditation, including specific brain networks and oscillations, and causal mechanisms of advanced meditation. Overall, NIBS-meditation research holds promise for enhancing meditation-based interventions in both non-clinical and clinical populations.
Neuroscience and Biobehavioral Reviews
July 1, 2024
Cheng Fan, Mengjiao Wu, Hong Liu et al.
A systematic review of 18 fMRI studies found that meditation alters brain activity in regions associated with pain, mood, and cognition. Activation of the insula, anterior cingulate cortex, and orbitofrontal cortex was positively linked to pain relief, while activity in the amygdala and medial prefrontal cortex was negatively correlated. Meta-analyses consistently implicated the insula, putamen, amygdala, anterior cingulate cortex, precentral gyrus, postcentral gyrus, inferior parietal lobule, superior temporal gyrus, inferior frontal gyrus, and caudate nucleus. These findings suggest meditation relieves pain by acting on specific neural circuits involved in both sensory and emotional pain processing.
Neuroscience and Biobehavioral Reviews
June 1, 2024
Robert Chis-Ciure, Lucia Melloni, Georg Northoff
A novel framework called the Measure Centrality Index (MCI) enables systematic comparison of consciousness theories by assessing how important a given empirical measure is for each theory. Applying the MCI to Global Neuronal Workspace Theory, Integrated Information Theory, and Temporospatial Theory of Consciousness shows that direct comparisons are meaningful for measures such as Lempel-Ziv Complexity, Autocorrelation Window, and possibly Mutual Information, but problematic for anatomical and physiological neural correlates of consciousness because these measures carry different weight across theories. The approach addresses isolated theory evolution and confirmatory bias in consciousness science.
Neuroscience and Biobehavioral Reviews
April 1, 2024
Niklas Reich, Michael Mannino, Steven Kotler
Caffeine, a non-selective adenosine receptor antagonist, may facilitate the flow state—an intrinsically rewarding condition of total task absorption and optimal performance—through several biological mechanisms. These include upregulating dopamine D1/D2 receptor affinity in reward-related brain areas, protecting dopaminergic neurons, increasing norepinephrine release and alertness, heightening parasympathetic high frequency heart rate variability, modifying striatal endocannabinoid-CB1 receptor signaling, and shifting brain network activity toward executive function. The review also discusses caffeine's application for attention deficit hyperactivity disorder and notes caveats, aiming to inspire future studies on caffeine-induced flow.
Neuroscience and Biobehavioral Reviews
December 1, 2023
T. Dominik, Alfred Mele, Aaron Schurger et al.
This paper provides a comprehensive review of the neuroscience of volition, summarizing research since its inception. The authors systematically reviewed 2,220 publications, with detailed consideration of nearly 500 relevant papers. They introduce Benjamin Libet's seminal work from the 1960s to 1980s and discuss common criticisms of his methods, including issues with temporal introspection, interpretation of physiological correlates, and conceptual problems. The review concludes with recent advances and future directions, highlighting modern methodological approaches and important findings. The authors aim to make the field accessible to newcomers and experts alike, covering both well-established research and under-discussed ideas.
Neuroscience and Biobehavioral Reviews
October 1, 2023
Ruben Laukkonen, Margaret Webb, Carola Salvi et al.
Feelings of insight help people select ideas from the stream of consciousness by capturing attention and generating intuitive confidence, enabling fast action under uncertainty. This 'Eureka heuristic' is explained through active inference: implicit restructuring via Bayesian reduction produces a higher-order prediction error (the content of insight), while dopaminergic precision-weighting of that error accounts for the confidence, pleasure, and attentional capture (the feeling of insight). The account aligns with the phenomenology, accuracy, and neural unfolding of insight, as well as its effects on belief and decision-making. Dangers include the formation and entrenchment of false beliefs and vulnerability of insights under psychoactive substances and misinformation.
Neuroscience and Biobehavioral Reviews
September 1, 2023
Carla Soares, Gerardo Gonzalo, João Castelhano et al.
The cingulate cortex, specifically Brodmann areas 23 and 31, is a key neural region where the Default Mode Network (DMN) and Theory of Mind (ToM) networks overlap. A meta-analysis of 88 studies with 2122 participants found that psychedelics affect this overlap, altering the neural basis of ToM and social cognition. These effects may underlie the therapeutic potential of psychedelics and deepen understanding of the neural correlates of the self.
Neuroscience and Biobehavioral Reviews
April 1, 2023
Péter Simor, Philippe Peigneux, Róbert Bódizs
Dreaming and the forgetting of dreams are not meaningless byproducts of sleep but are integral to the brain's homeostatic functions, which both restore and anticipate future needs. Mental activity during sleep, especially in the second half of the night, is a self-focused, future-oriented cognitive process. Waking up shifts the brain to a constrained, goal-directed mode of thinking that competes for neural resources with dream production and recall, contributing to dream amnesia. Cortisol is highlighted as a potential factor in predictive homeostasis and forgetting dreams. This theoretical proposal reframes dreaming as part of a reactive and predictive homeostatic system.
Neuroscience and Biobehavioral Reviews
November 1, 2022
Megan A. K. Peters
Perceptual metacognition—the ability to reflect on one's own perceptual experiences, such as feeling confident about a decision—offers a promising entry point for studying the neural and computational basis of subjective conscious experience. This review identifies five unique properties of metacognition that make it empirically tractable: it produces subjective feelings, is directed at internal representations, involves recursive computations, is linked to observable behavior, and requires sensitive models because its computations are unobservable yet hierarchically dependent. Computational models of metacognition can help characterize the generative processes that construct qualitative experience, drawing on advances in psychology, neuroscience, and philosophy.