201
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Carhart-Harris RL, Friston KJ. REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics. Pharmacol Rev 2019; 71:316-344. [PMID: 31221820 PMCID: PMC6588209 DOI: 10.1124/pr.118.017160] [Citation(s) in RCA: 373] [Impact Index Per Article: 74.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
This paper formulates the action of psychedelics by integrating the free-energy principle and entropic brain hypothesis. We call this formulation relaxed beliefs under psychedelics (REBUS) and the anarchic brain, founded on the principle that-via their entropic effect on spontaneous cortical activity-psychedelics work to relax the precision of high-level priors or beliefs, thereby liberating bottom-up information flow, particularly via intrinsic sources such as the limbic system. We assemble evidence for this model and show how it can explain a broad range of phenomena associated with the psychedelic experience. With regard to their potential therapeutic use, we propose that psychedelics work to relax the precision weighting of pathologically overweighted priors underpinning various expressions of mental illness. We propose that this process entails an increased sensitization of high-level priors to bottom-up signaling (stemming from intrinsic sources), and that this heightened sensitivity enables the potential revision and deweighting of overweighted priors. We end by discussing further implications of the model, such as that psychedelics can bring about the revision of other heavily weighted high-level priors, not directly related to mental health, such as those underlying partisan and/or overly-confident political, religious, and/or philosophical perspectives. SIGNIFICANCE STATEMENT: Psychedelics are capturing interest, with efforts underway to bring psilocybin therapy to marketing authorisation and legal access within a decade, spearheaded by the findings of a series of phase 2 trials. In this climate, a compelling unified model of how psychedelics alter brain function to alter consciousness would have appeal. Towards this end, we have sought to integrate a leading model of global brain function, hierarchical predictive coding, with an often-cited model of the acute action of psychedelics, the entropic brain hypothesis. The resulting synthesis states that psychedelics work to relax high-level priors, sensitising them to liberated bottom-up information flow, which, with the right intention, care provision and context, can help guide and cultivate the revision of entrenched pathological priors.
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Affiliation(s)
- R L Carhart-Harris
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
| | - K J Friston
- Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, London, United Kingdom (R.L.C.-H.); and Institute of Neurology, Wellcome Trust Centre for Neuroimaging, University College London, London, United Kingdom (K.J.F.)
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202
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"Average is good, extremes are bad" - Non-linear inverted U-shaped relationship between neural mechanisms and functionality of mental features. Neurosci Biobehav Rev 2019; 104:11-25. [PMID: 31251964 DOI: 10.1016/j.neubiorev.2019.06.030] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 06/18/2019] [Accepted: 06/20/2019] [Indexed: 01/22/2023]
Abstract
Traditionally, studies emphasize differences in neural measures between pathological and healthy groups, assuming a binary distinction between the groups, and a linear relationship between neural measures and symptoms. Here, we present four examples that show a continuous relation across the divide of normal and pathological states between neural measures and mental functions. This relation can be characterized by a non-linear inverted-U shaped curve. Along this curve, mid-range or average expression of a neural measure is associated with optimal function of a mental feature (in healthy states), whereas extreme expression, either high or low, is associated with sub-optimal function, and occurs in different neural disorders. Neural expression between the optimal or intermediate and pathological or extreme values is associated with sub-optimal function and at-risk mental states. Thus, this model of neuro-mental relationship can be summarized as "average is good, extremes are bad". By focussing on neuro-mental relationships, this model can facilitate the transition of psychiatry from a categorical to a dimensional and individualized approach needed in the era of precision medicine.
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203
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204
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Northoff G, Wainio-Theberge S, Evers K. Is temporo-spatial dynamics the "common currency" of brain and mind? In Quest of "Spatiotemporal Neuroscience". Phys Life Rev 2019; 33:34-54. [PMID: 31221604 DOI: 10.1016/j.plrev.2019.05.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 05/21/2019] [Indexed: 12/20/2022]
Abstract
Neuroscience has made considerable progress in unraveling the neural correlates of mental phenomena like self, consciousness, and perception. However, the "common currency" shared between neuronal and mental activity, brain and mind, remains yet unclear. In this article, we propose that the dynamics of time and space provides a "common currency" that connects neuronal and mental features. Time and space are here understood in a dynamic context (as in contemporary physics): that is, in terms of the way the brain's spontaneous activity constructs its spatial and temporal relationships, for instance in terms of functional connectivity and different frequencies of fluctuations. Recruiting recent empirical evidence, we show that the different ways in which the spontaneous activity constructs its "inner time and space" are manifested in distinct mental features. Specifically, we demonstrate how spatiotemporal mechanisms like spatiotemporal repertoire, integration, and speed yield mental features like consciousness, self, and time speed perception. The focus on the brain's spatiotemporal mechanisms entails what we describe as "Spatiotemporal Neuroscience". Spatiotemporal Neuroscience conceives neuronal activity in terms of its temporo-spatial dynamics rather than its various functions (e.g., cognitive, affective, social, etc.) as in other branches of neuroscience (as distinguished from Cognitive, Affective, Cultural, Social, etc. Neuroscience). That allows Spatiotemporal Neuroscience to take into view the so-called 'spatio-temporality' of mental features including their non-causal, intrinsic and transformative relationship with neuronal features. In conclusion, Spatiotemporal Neuroscience opens the door to investigate and ultimately reveal the brain's own temporo-spatial dynamics as the hitherto missing "common currency" of neuronal and mental features.
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Affiliation(s)
- Georg Northoff
- Mental Health Center, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa, Ottawa, Canada; Centre for Research Ethics & Bioethics, University of Uppsala, Uppsala, Sweden. http://www.georgnorthoff.com
| | - Soren Wainio-Theberge
- Mind, Brain Imaging and Neuroethics, Institute of Mental Health Research, University of Ottawa, Ottawa, Canada
| | - Kathinka Evers
- Centre for Research Ethics & Bioethics, University of Uppsala, Uppsala, Sweden
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205
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Scott G, Carhart-Harris RL. Psychedelics as a treatment for disorders of consciousness. Neurosci Conscious 2019; 2019:niz003. [PMID: 31024740 PMCID: PMC6475593 DOI: 10.1093/nc/niz003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 03/06/2019] [Accepted: 03/06/2019] [Indexed: 11/23/2022] Open
Abstract
Based on its ability to increase brain complexity, a seemingly reliable index of conscious level, we propose testing the capacity of the classic psychedelic, psilocybin, to increase conscious awareness in patients with disorders of consciousness. We also confront the considerable ethical and practical challenges this proposal must address, if this hypothesis is to be directly assessed.
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Affiliation(s)
- Gregory Scott
- Department of Medicine, The Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, 3rd Floor, Burlington Danes Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Robin L Carhart-Harris
- Department of Medicine, The Computational, Cognitive and Clinical Neuroimaging Laboratory, Division of Brain Sciences, Imperial College London, 3rd Floor, Burlington Danes Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
- Department of Medicine, Centre for Psychedelic Research, Division of Brain Sciences, Imperial College London, 5th Floor, Burlington Danes Building, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
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206
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Lake J. The near-death experience (NDE) as an inherited predisposition: Possible genetic, epigenetic, neural and symbolic mechanisms. Med Hypotheses 2019; 126:135-148. [PMID: 31010490 DOI: 10.1016/j.mehy.2019.03.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 02/24/2019] [Accepted: 03/21/2019] [Indexed: 12/21/2022]
Affiliation(s)
- James Lake
- Center for Integrative Medicine, University of Arizona College of Medicine, Tucson, AZ, United States.
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207
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Perceptual phenomena in destructured sensory fields: Probing the brain’s intrinsic functional architectures. Neurosci Biobehav Rev 2019; 98:265-286. [DOI: 10.1016/j.neubiorev.2019.01.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 01/13/2019] [Accepted: 01/14/2019] [Indexed: 12/20/2022]
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208
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Miskovic V, MacDonald KJ, Rhodes LJ, Cote KA. Changes in EEG multiscale entropy and power-law frequency scaling during the human sleep cycle. Hum Brain Mapp 2019; 40:538-551. [PMID: 30259594 PMCID: PMC6865770 DOI: 10.1002/hbm.24393] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/29/2018] [Accepted: 08/31/2018] [Indexed: 02/06/2023] Open
Abstract
We explored changes in multiscale brain signal complexity and power-law scaling exponents of electroencephalogram (EEG) frequency spectra across several distinct global states of consciousness induced in the natural physiological context of the human sleep cycle. We specifically aimed to link EEG complexity to a statistically unified representation of the neural power spectrum. Further, by utilizing surrogate-based tests of nonlinearity we also examined whether any of the sleep stage-dependent changes in entropy were separable from the linear stochastic effects contained in the power spectrum. Our results indicate that changes of brain signal entropy throughout the sleep cycle are strongly time-scale dependent. Slow wave sleep was characterized by reduced entropy at short time scales and increased entropy at long time scales. Temporal signal complexity (at short time scales) and the slope of EEG power spectra appear, to a large extent, to capture a common phenomenon of neuronal noise, putatively reflecting cortical balance between excitation and inhibition. Nonlinear dynamical properties of brain signals accounted for a smaller portion of entropy changes, especially in stage 2 sleep.
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Affiliation(s)
- Vladimir Miskovic
- Department of PsychologyState University of New York at BinghamtonBinghamtonNew York
- Center for Affective ScienceState University of New York at BinghamtonBinghamtonNew York
| | | | - L. Jack Rhodes
- Department of PsychologyState University of New York at BinghamtonBinghamtonNew York
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209
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Characterizing Complex Networks Using Entropy-Degree Diagrams: Unveiling Changes in Functional Brain Connectivity Induced by Ayahuasca. ENTROPY 2019; 21:e21020128. [PMID: 33266844 PMCID: PMC7514607 DOI: 10.3390/e21020128] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/13/2019] [Accepted: 01/30/2019] [Indexed: 12/31/2022]
Abstract
With the aim of further advancing the understanding of the human brain’s functional connectivity, we propose a network metric which we term the geodesic entropy. This metric quantifies the Shannon entropy of the distance distribution to a specific node from all other nodes. It allows to characterize the influence exerted on a specific node considering statistics of the overall network structure. The measurement and characterization of this structural information has the potential to greatly improve our understanding of sustained activity and other emergent behaviors in networks. We apply this method to study how the psychedelic infusion Ayahuasca affects the functional connectivity of the human brain in resting state. We show that the geodesic entropy is able to differentiate functional networks of the human brain associated with two different states of consciousness in the awaking resting state: (i) the ordinary state and (ii) a state altered by ingestion of the Ayahuasca. The functional brain networks from subjects in the altered state have, on average, a larger geodesic entropy compared to the ordinary state. Finally, we discuss why the geodesic entropy may bring even further valuable insights into the study of the human brain and other empirical networks.
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210
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Josipovic Z. Nondual awareness: Consciousness-as-such as non-representational reflexivity. PROGRESS IN BRAIN RESEARCH 2019; 244:273-298. [PMID: 30732841 DOI: 10.1016/bs.pbr.2018.10.021] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
I introduce arguments toward a non-representational reflexivity theory of consciousness-as-such to address one of the key issues in the science of consciousness today: lack of understanding of the nature of consciousness itself. An expanded map of consciousness is outlined, which includes, in addition to the well-known contents of awareness and levels of arousal, the indeterminate substrate and consciousness-as-such or nondual awareness. The central idea presented is that consciousness-as-such is a non-conceptual nondual awareness, whose essential property is non-representational reflexivity. This property makes consciousness-as-such phenomenologically, cognitively and neurobiologically a unique kind, different from and irreducible to any contents, functions and states, including the indeterminate substrate. Our previous hypothesis on the precuneus network for nondual awareness is further discussed in relation to non-representational reflexivity, and in the light of other hypotheses on the neural correlates of consciousness-as-such.
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Affiliation(s)
- Zoran Josipovic
- Psychology Department, Graduate School of Arts and Sciences, New York University, New York, NY, United States; NYU Langone Medical Center, NYU School of Medicine, New York, NY, United States; Nonduality Institute, Woodstock, NY, United States.
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211
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Heal DJ, Henningfield J, Frenguelli BG, Nutt DJ, Smith SL. Psychedelics – Re-opening the doors of perception. Neuropharmacology 2018; 142:1-6. [PMID: 30144477 DOI: 10.1016/j.neuropharm.2018.08.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- David J Heal
- RenaSci Ltd, BioCity, Nottingham NG1 1GF, UK; Department of Pharmacy & Pharmacology, University of Bath, Bath, BA2 7AY, UK.
| | - Jack Henningfield
- Pinney Associates, Bethesda, MD, 20814, USA; Department of Psychiatry and Behavioral Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
| | | | - David J Nutt
- Centre for Psychiatry, Division of Brain Sciences, Imperial College London, W12 0NN, UK.
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212
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Raison CL. Everything old is new again: are psychedelic medicines poised to take mental health by storm? Acta Psychiatr Scand 2018; 138:365-367. [PMID: 30367469 DOI: 10.1111/acps.12975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Charles L Raison
- Department of Human Development and Family Studies, School of Human Ecology, University of Wisconsin-Madison, Madison, WI, USA.,Usona Institute, Fitchberg, WI, USA.,Emory Healthcare, Atlanta, GA, USA
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213
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Atasoy S, Vohryzek J, Deco G, Carhart-Harris RL, Kringelbach ML. Common neural signatures of psychedelics: Frequency-specific energy changes and repertoire expansion revealed using connectome-harmonic decomposition. PROGRESS IN BRAIN RESEARCH 2018; 242:97-120. [PMID: 30471684 DOI: 10.1016/bs.pbr.2018.08.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The search for the universal laws of human brain function is still on-going but progress is being made. Here we describe the novel concepts of connectome harmonics and connectome-harmonic decomposition, which can be used to characterize the brain activity associated with any mental state. We use this new frequency-specific language to describe the brain activity elicited by psilocybin and LSD and find remarkably similar effects in terms of increases in total energy and power, as well as frequency-specific energy changes and repertoire expansion. In addition, we find enhanced signatures of criticality suggesting that the brain dynamics tune toward criticality in both psychedelic elicited states. Overall, our findings provide new evidence for the remarkable ability of psychedelics to change the spatiotemporal dynamics of the human brain.
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Affiliation(s)
- Selen Atasoy
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom; Center for Music in the Brain, Aarhus University, Aarhus, Denmark
| | - Jakub Vohryzek
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom; Center for Music in the Brain, Aarhus University, Aarhus, Denmark
| | - Gustavo Deco
- Center for Brain and Cognition, Computational Neuroscience Group, Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain; Institució Catalana de la Recerca i Estudis Avançats (ICREA), Barcelona, Spain; Department of Neuropsychology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; School of Psychological Sciences, Monash University, Melbourne, Australia
| | | | - Morten L Kringelbach
- Department of Psychiatry, University of Oxford, Oxford, United Kingdom; Center for Music in the Brain, Aarhus University, Aarhus, Denmark.
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214
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Dolan D, Jensen HJ, Mediano PAM, Molina-Solana M, Rajpal H, Rosas F, Sloboda JA. The Improvisational State of Mind: A Multidisciplinary Study of an Improvisatory Approach to Classical Music Repertoire Performance. Front Psychol 2018; 9:1341. [PMID: 30319469 PMCID: PMC6167963 DOI: 10.3389/fpsyg.2018.01341] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/12/2018] [Indexed: 11/13/2022] Open
Abstract
The recent re-introduction of improvisation as a professional practice within classical music, however cautious and still rare, allows direct and detailed contemporary comparison between improvised and "standard" approaches to performances of the same composition, comparisons which hitherto could only be inferred from impressionistic historical accounts. This study takes an interdisciplinary multi-method approach to discovering the contrasting nature and effects of prepared and improvised approaches during live chamber-music concert performances of a movement from Franz Schubert's "Shepherd on the Rock," given by a professional trio consisting of voice, flute, and piano, in the presence of an invited audience of 22 adults with varying levels of musical experience and training. The improvised performances were found to differ systematically from prepared performances in their timing, dynamic, and timbral features as well as in the degree of risk-taking and "mind reading" between performers, which included moments of spontaneously exchanging extemporized notes. Post-performance critical reflection by the performers characterized distinct mental states underlying the two modes of performance. The amount of overall body movements was reduced in the improvised performances, which showed less unco-ordinated movements between performers when compared to the prepared performance. Audience members, who were told only that the two performances would be different, but not how, rated the improvised version as more emotionally compelling and musically convincing than the prepared version. The size of this effect was not affected by whether or not the audience could see the performers, or by levels of musical training. EEG measurements from 19 scalp locations showed higher levels of Lempel-Ziv complexity (associated with awareness and alertness) in the improvised version in both performers and audience. Results are discussed in terms of their potential support for an "improvisatory state of mind" which may have aspects of flow (as characterized by Csikszentmihalyi, 1997) and primary states (as characterized by the Entropic Brain Hypothesis of Carhart-Harris et al., 2014). In a group setting, such as a live concert, our evidence suggests that this state of mind is communicable between performers and audience thus contributing to a heightened quality of shared experience.
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Affiliation(s)
- David Dolan
- Guildhall School of Music and Drama, London, United Kingdom
| | - Henrik J. Jensen
- Department of Mathematics, Centre of Complexity Science, Imperial College London, London, United Kingdom
- Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan
| | | | - Miguel Molina-Solana
- Department of Computing, Imperial College London, London, United Kingdom
- Data Science Institute, Imperial College London, London, United Kingdom
| | - Hardik Rajpal
- Department of Mathematics, Centre of Complexity Science, Imperial College London, London, United Kingdom
| | - Fernando Rosas
- Department of Mathematics, Centre of Complexity Science, Imperial College London, London, United Kingdom
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
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215
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Bayne T, Carter O. Dimensions of consciousness and the psychedelic state. Neurosci Conscious 2018; 2018:niy008. [PMID: 30254752 PMCID: PMC6146157 DOI: 10.1093/nc/niy008] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/06/2018] [Accepted: 07/02/2018] [Indexed: 01/21/2023] Open
Abstract
It has often been suggested in the popular and academic literature that the psychedelic state qualifies as a higher state of consciousness relative to the state of normal waking awareness. This article subjects this proposal to critical scrutiny, focusing on the question of what it would mean for a state of consciousness to be 'higher'. We begin by considering the contrast between conscious contents and conscious global states. We then review the changes in conscious global state associated with psychedelic drug use, focusing on the effects of two serotonergic hallucinogens: psilocybin and lysergic acid diethylamide. Limiting our review to findings obtained from lab-based experiments and reported in peer-reviewed journals, we prioritize the more common and reliably induced effects obtained through subjective questionnaires and psychophysical measures. The findings are grouped into three broad categories (sensory perception, cognitive function, and experiences of unity) and demonstrate that although certain aspects of consciousness are improved or enhanced in the psychedelic state, many of the functional capacities that are associated with consciousness are seriously compromised. Psychedelic-induced states of consciousness are indeed remarkable in many ways, but it is inappropriate to regard them as 'higher' states of consciousness. The fact that psychedelics affect different aspects of consciousness in fundamentally different ways provides evidence against the unidimensional (or 'level-based') view of consciousness, and instead provides strong support for a multidimensional conception of conscious states. The final section of the article considers the implications of this analysis for two prominent theories of consciousness: the Global Workspace Theory and Integrated Information Theory.
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Affiliation(s)
- Tim Bayne
- School of Philosophical, Historical and International Studies, 20 Chancellors Walk, Monash University, VIC, Australia
| | - Olivia Carter
- School of Psychological Sciences, University of Melbourne, Parkville, VIC, Australia
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216
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Timmermann C, Roseman L, Williams L, Erritzoe D, Martial C, Cassol H, Laureys S, Nutt D, Carhart-Harris R. DMT Models the Near-Death Experience. Front Psychol 2018; 9:1424. [PMID: 30174629 PMCID: PMC6107838 DOI: 10.3389/fpsyg.2018.01424] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/20/2018] [Indexed: 12/12/2022] Open
Abstract
Near-death experiences (NDEs) are complex subjective experiences, which have been previously associated with the psychedelic experience and more specifically with the experience induced by the potent serotonergic, N,N-Dimethyltryptamine (DMT). Potential similarities between both subjective states have been noted previously, including the subjective feeling of transcending one's body and entering an alternative realm, perceiving and communicating with sentient 'entities' and themes related to death and dying. In this within-subjects placebo-controled study we aimed to test the similarities between the DMT state and NDEs, by administering DMT and placebo to 13 healthy participants, who then completed a validated and widely used measure of NDEs. Results revealed significant increases in phenomenological features associated with the NDE, following DMT administration compared to placebo. Also, we found significant relationships between the NDE scores and DMT-induced ego-dissolution and mystical-type experiences, as well as a significant association between NDE scores and baseline trait 'absorption' and delusional ideation measured at baseline. Furthermore, we found a significant overlap in nearly all of the NDE phenomenological features when comparing DMT-induced NDEs with a matched group of 'actual' NDE experiencers. These results reveal a striking similarity between these states that warrants further investigation.
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Affiliation(s)
- Christopher Timmermann
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom.,The Computational, Cognitive & Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom
| | - Leor Roseman
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom.,The Computational, Cognitive & Clinical Neuroimaging Laboratory, Department of Medicine, Imperial College London, London, United Kingdom
| | - Luke Williams
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom
| | - David Erritzoe
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom
| | - Charlotte Martial
- GIGA-Consciousness and Neurology Department, Coma Science Group, University of Liège and University Hospital of Liège, Liège, Belgium
| | - Héléna Cassol
- GIGA-Consciousness and Neurology Department, Coma Science Group, University of Liège and University Hospital of Liège, Liège, Belgium
| | - Steven Laureys
- GIGA-Consciousness and Neurology Department, Coma Science Group, University of Liège and University Hospital of Liège, Liège, Belgium
| | - David Nutt
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom
| | - Robin Carhart-Harris
- Psychedelic Research Group, Centre for Psychiatry, Department of Medicine, Imperial College London, London, United Kingdom
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