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Katyal S, Abdoun O, Mounier H, Lutz A. Reduced processing of afforded actions while observing mental content as ongoing mental phenomena. Sci Rep 2024; 14:10130. [PMID: 38698150 PMCID: PMC11065984 DOI: 10.1038/s41598-024-60934-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 04/29/2024] [Indexed: 05/05/2024] Open
Abstract
While consciousness is typically considered equivalent to mental contents, certain meditation practices-including open monitoring (OM)-are said to enable a unique conscious state where meditators can experience mental content from a de-reified perspective as "ongoing phenomena." Phenomenologically, such a state is considered as reduction of intentionality, the mental act upon mental content. We hypothesised that this de-reified state would be characterised by reduced mental actional processing of affording objects. We recruited two groups of participants, meditators with long-term experience in cultivating a de-reified state, and demographically-matched novice meditators. Participants performed a task with images in two configurations-where objects did (high-affordance) and did not imply actions (low-affordance)-following both a baseline and OM-induced de-reified state, along with EEG recordings. While long-term meditators exhibited preferential processing of high-affordance images compared to low-affordance images during baseline, such an effect was abolished during the OM state, as hypothesised. For novices, however, the high-affordance configuration was preferred over the low-affordance one both during baseline and OM. Perceptual durations of objects across conditions positively correlated with the degree of µ-rhythm desynchronization, indicating that neural processing of affordance impacted perceptual awareness. Our results indicate that OM styles of meditation may help in mentally decoupling otherwise automatic cognitive processing of mental actions by affording objects.
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Affiliation(s)
- Sucharit Katyal
- EDUWELL Team, Lyon Neuroscience Research Centre, INSERM U1028, CNRS UMR5292, Lyon 1 University, Lyon, France.
- Department of Psychology, University of Copenhagen, Copenhagen, Denmark.
| | - Oussama Abdoun
- EDUWELL Team, Lyon Neuroscience Research Centre, INSERM U1028, CNRS UMR5292, Lyon 1 University, Lyon, France
| | - Hugues Mounier
- L2S - Laboratoire des signaux et systemes, Université Paris-Saclay, CentraleSupélec, CNRS, Gif Sur Yvette, France
| | - Antoine Lutz
- EDUWELL Team, Lyon Neuroscience Research Centre, INSERM U1028, CNRS UMR5292, Lyon 1 University, Lyon, France.
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Wilson M, Hecker L, Joos E, Aertsen A, Tebartz van Elst L, Kornmeier J. Spontaneous Necker-cube reversals may not be that spontaneous. Front Hum Neurosci 2023; 17:1179081. [PMID: 37323933 PMCID: PMC10268006 DOI: 10.3389/fnhum.2023.1179081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 04/28/2023] [Indexed: 06/17/2023] Open
Abstract
Introduction During observation of the ambiguous Necker cube, our perception suddenly reverses between two about equally possible 3D interpretations. During passive observation, perceptual reversals seem to be sudden and spontaneous. A number of theoretical approaches postulate destabilization of neural representations as a pre-condition for reversals of ambiguous figures. In the current study, we focused on possible Electroencephalogram (EEG) correlates of perceptual destabilization, that may allow prediction of an upcoming perceptual reversal. Methods We presented ambiguous Necker cube stimuli in an onset-paradigm and investigated the neural processes underlying endogenous reversals as compared to perceptual stability across two consecutive stimulus presentations. In a separate experimental condition, disambiguated cube variants were alternated randomly, to exogenously induce perceptual reversals. We compared the EEG immediately before and during endogenous Necker cube reversals with corresponding time windows during exogenously induced perceptual reversals of disambiguated cube variants. Results For the ambiguous Necker cube stimuli, we found the earliest differences in the EEG between reversal trials and stability trials already 1 s before a reversal occurred, at bilateral parietal electrodes. The traces remained similar until approximately 1100 ms before a perceived reversal, became maximally different at around 890 ms (p = 7.59 × 10-6, Cohen's d = 1.35) and remained different until shortly before offset of the stimulus preceding the reversal. No such patterns were found in the case of disambiguated cube variants. Discussion The identified EEG effects may reflect destabilized states of neural representations, related to destabilized perceptual states preceding a perceptual reversal. They further indicate that spontaneous Necker cube reversals are most probably not as spontaneous as generally thought. Rather, the destabilization may occur over a longer time scale, at least 1 s before a reversal event, despite the reversal event as such being perceived as spontaneous by the viewer.
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Affiliation(s)
- Mareike Wilson
- Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Lukas Hecker
- Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- Department of Psychosomatic Medicine and Psychotherapy, Medical Center – University of Freiburg, Freiburg, Germany
| | - Ellen Joos
- INSERM U1114, Cognitive Neuropsychology and Pathophysiology of Schizophrenia, Strasbourg, France
| | - Ad Aertsen
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
| | - Ludger Tebartz van Elst
- Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jürgen Kornmeier
- Department of Psychiatry and Psychotherapy, Medical Center – University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
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Hecker L, Tebartz van Elst L, Kornmeier J. Source localization using recursively applied and projected MUSIC with flexible extent estimation. Front Neurosci 2023; 17:1170862. [PMID: 37255753 PMCID: PMC10225686 DOI: 10.3389/fnins.2023.1170862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/17/2023] [Indexed: 06/01/2023] Open
Abstract
Magneto- and electroencephalography (M/EEG) are widespread techniques to measure neural activity in-vivo at a high temporal resolution but low spatial resolution. Locating the neural sources underlying the M/EEG poses an inverse problem, which is ill-posed. We developed a new method based on Recursive Application of Multiple Signal Classification (MUSIC). Our proposed method is able to recover not only the locations but, in contrast to other inverse solutions, also the extent of active brain regions flexibly (FLEX-MUSIC). This is achieved by allowing it to search not only for single dipoles but also dipole clusters of increasing extent to find the best fit during each recursion. FLEX-MUSIC achieved the highest accuracy for both single dipole and extended sources compared to all other methods tested. Remarkably, FLEX-MUSIC was capable to accurately estimate the level of sparsity in the source space (r = 0.82), whereas all other approaches tested failed to do so (r ≤ 0.18). The average computation time of FLEX-MUSIC was considerably lower compared to a popular Bayesian approach and comparable to that of another recursive MUSIC approach and eLORETA. FLEX-MUSIC produces only few errors and was capable to reliably estimate the extent of sources. The accuracy and low computation time of FLEX-MUSIC renders it an improved technique to solve M/EEG inverse problems both in neuroscience research and potentially in pre-surgery diagnostic in epilepsy.
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Affiliation(s)
- Lukas Hecker
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center, Freiburg, Germany
- Department of Psychosomatic Medicine and Psychotherapy, University of Freiburg Medical Center, Freiburg, Germany
- Perception and Cognition Lab, Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ludger Tebartz van Elst
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jürgen Kornmeier
- Department of Psychiatry and Psychotherapy, University of Freiburg Medical Center, Freiburg, Germany
- Perception and Cognition Lab, Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Faculty of Biology, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Katyal S, Goldin P. Neural correlates of nonjudgmental perception induced through meditation. Ann N Y Acad Sci 2021; 1499:70-81. [PMID: 33893655 DOI: 10.1111/nyas.14603] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/25/2021] [Accepted: 04/07/2021] [Indexed: 12/26/2022]
Abstract
Ambiguous sensory stimuli provide insight into the dynamics of the human mind. When viewing substantially different images in the two eyes (i.e., binocular rivalry (BR)), perception spontaneously fluctuates between the two images along with patch-like mixtures of the two, with limited ability to control such fluctuations. Previous studies have shown that long-term meditation training can enable a more stable perception by reducing such fluctuations. Using electroencephalography, we investigated the neural bases of perceptual stabilization in long-term meditators (LTMs) and age-matched meditation-naive control participants. We measured BR alternations before and after participants practiced meditation. We expected that perceptual stabilization through meditation could occur via one of two neurocognitive mechanisms: (1) a more engaged/effortful attention reflected by increased long-range phase synchronization between early visual sensory and higher-level brain regions, or (2) a disengaged/nonevaluative form of attention reflected by decreased phase synchronization. We found that compared with control participants, LTMs were in a significantly longer mixed perceptual state following concentrative meditation practice. The increase in mixed percepts across individuals was strongly correlated with reduced parietal-occipital gamma-band (30-50 Hz) phase synchrony. These findings suggest that concentrative meditation enables a nonevaluative perceptual stance supported by reduced communication between hierarchical visual brain regions.
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Affiliation(s)
- Sucharit Katyal
- University of California Davis Medical Center, Sacramento, California
| | - Philippe Goldin
- University of California Davis Medical Center, Sacramento, California
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Kent L, Wittmann M. Special Issue: Consciousness science and its theories Time consciousness: the missing link in theories of consciousness. Neurosci Conscious 2021; 2021:niab011. [PMID: 33868714 PMCID: PMC8042366 DOI: 10.1093/nc/niab011] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 03/08/2021] [Accepted: 03/16/2021] [Indexed: 11/26/2022] Open
Abstract
There are plenty of issues to be solved in order for researchers to agree on a neural model of consciousness. Here we emphasize an often under-represented aspect in the debate: time consciousness. Consciousness and the present moment both extend in time. Experience flows through a succession of moments and progresses from future predictions, to present experiences, to past memories. However, a brief review finds that many dominant theories of consciousness only refer to brief, static, and discrete "functional moments" of time. Very few refer to more extended, dynamic, and continuous time, which is associated with conscious experience (cf. the "experienced moment"). This confusion between short and discrete versus long and continuous is, we argue, one of the core issues in theories of consciousness. Given the lack of work dedicated to time consciousness, its study could test novel predictions of rival theories of consciousness. It may be that different theories of consciousness are compatible/complementary if the different aspects of time are taken into account. Or, if it turns out that no existing theory can fully accommodate time consciousness, then perhaps it has something new to add. Regardless of outcome, the crucial step is to make subjective time a central object of study.
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Affiliation(s)
- Lachlan Kent
- Centre for Youth Mental Health, The University of Melbourne, 35 Poplar Rd, Parkville, Victoria 3052, Australia
- Orygen, 35 Poplar Rd, Parkville, Victoria 3052, Australia
| | - Marc Wittmann
- Institute for Frontier Areas of Psychology and Mental Health, Wilhelmstraße 3a, 79098 Freiburg i.Br., Germany
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Deolindo CS, Ribeiro MW, Aratanha MA, Afonso RF, Irrmischer M, Kozasa EH. A Critical Analysis on Characterizing the Meditation Experience Through the Electroencephalogram. Front Syst Neurosci 2020; 14:53. [PMID: 32848645 PMCID: PMC7427581 DOI: 10.3389/fnsys.2020.00053] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 07/06/2020] [Indexed: 11/13/2022] Open
Abstract
Meditation practices, originated from ancient traditions, have increasingly received attention due to their potential benefits to mental and physical health. The scientific community invests efforts into scrutinizing and quantifying the effects of these practices, especially on the brain. There are methodological challenges in describing the neural correlates of the subjective experience of meditation. We noticed, however, that technical considerations on signal processing also don't follow standardized approaches, which may hinder generalizations. Therefore, in this article, we discuss the usage of the electroencephalogram (EEG) as a tool to study meditation experiences in healthy individuals. We describe the main EEG signal processing techniques and how they have been translated to the meditation field until April 2020. Moreover, we examine in detail the limitations/assumptions of these techniques and highlight some good practices, further discussing how technical specifications may impact the interpretation of the outcomes. By shedding light on technical features, this article contributes to more rigorous approaches to evaluate the construct of meditation.
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Affiliation(s)
| | | | | | | | - Mona Irrmischer
- Department of Integrative Neurogenomics and Cognitive Research (CNCR), Amsterdam Neuroscience, VU Amsterdam, Amsterdam, Netherlands
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Polgári P, Causin JB, Weiner L, Bertschy G, Giersch A. Novel method to measure temporal windows based on eye movements during viewing of the Necker cube. PLoS One 2020; 15:e0227506. [PMID: 31940327 PMCID: PMC6961897 DOI: 10.1371/journal.pone.0227506] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/19/2019] [Indexed: 11/18/2022] Open
Abstract
Bistable stimuli can give rise to two different interpretations between which our perception will alternate. Recent results showed a strong coupling between eye movements and reports of perceptual alternations with motion stimuli, which provides useful tools to objectively assess perceptual alternations. However, motion might entrain eye movements, and here we check with a static picture, the Necker cube, whether eye movements and perceptual reports (manual responses) reveal similar or different alternation rates, and similar or different sensitivity to attention manipulations. Using a cluster analysis, ocular temporal windows were defined based on the dynamics of ocular fixations during viewing of the Necker cube and compared to temporal windows extracted from manual responses. Ocular temporal windows were measured also with a control condition, where the physical stimulus presented to viewers alternated between two non-ambiguous versions of the Necker cube. Attention was manipulated by asking subjects to either report spontaneous alternations, focus on one percept, or switch as fast as possible between percepts. The validity of the ocular temporal windows was confirmed by the correspondence between ocular fixations when the physical stimulus changed and when the bistable Necker cube was presented. Ocular movements defined smaller time windows than time windows extracted from manual responses. The number of manual and ocular windows both increased between the spontaneous condition and the switch condition. However, only manual, and not ocular windows, increased in duration in the focus condition. Manual responses involve decisional mechanisms, and they may be decoupled from automatic oscillations between the two percepts, as suggested by the fact that both the number and duration of ocular windows remained stable between the spontaneous and focus conditions. In all, the recording of eye movements provides an objective measure of time windows, and reveals faster perceptual alternations with the Necker cube and less sensitivity to attention manipulations than manual responses.
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Affiliation(s)
- Patrik Polgári
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
| | - Jean-Baptiste Causin
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Luisa Weiner
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Gilles Bertschy
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Anne Giersch
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
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