1
|
Shenyan O, Lisi M, Greenwood JA, Skipper JI, Dekker TM. Visual hallucinations induced by Ganzflicker and Ganzfeld differ in frequency, complexity, and content. Sci Rep 2024; 14:2353. [PMID: 38287084 PMCID: PMC10825158 DOI: 10.1038/s41598-024-52372-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/17/2024] [Indexed: 01/31/2024] Open
Abstract
Visual hallucinations can be phenomenologically divided into those of a simple or complex nature. Both simple and complex hallucinations can occur in pathological and non-pathological states, and can also be induced experimentally by visual stimulation or deprivation-for example using a high-frequency, eyes-open flicker (Ganzflicker) and perceptual deprivation (Ganzfeld). Here we leverage the differences in visual stimulation that these two techniques involve to investigate the role of bottom-up and top-down processes in shifting the complexity of visual hallucinations, and to assess whether these techniques involve a shared underlying hallucinatory mechanism despite their differences. For each technique, we measured the frequency and complexity of the hallucinations produced, utilising button presses, retrospective drawing, interviews, and questionnaires. For both experimental techniques, simple hallucinations were more common than complex hallucinations. Crucially, we found that Ganzflicker was more effective than Ganzfeld at eliciting simple hallucinations, while complex hallucinations remained equivalent across the two conditions. As a result, the likelihood that an experienced hallucination was complex was higher during Ganzfeld. Despite these differences, we found a correlation between the frequency and total time spent hallucinating in Ganzflicker and Ganzfeld conditions, suggesting some shared mechanisms between the two methodologies. We attribute the tendency to experience frequent simple hallucinations in both conditions to a shared low-level core hallucinatory mechanism, such as excitability of visual cortex, potentially amplified in Ganzflicker compared to Ganzfeld due to heightened bottom-up input. The tendency to experience complex hallucinations, in contrast, may be related to top-down processes less affected by visual stimulation.
Collapse
Affiliation(s)
- Oris Shenyan
- Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, UK.
- Institute of Ophthalmology, University College London, London, UK.
| | - Matteo Lisi
- Department of Psychology, Royal Holloway University, London, UK
| | - John A Greenwood
- Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, UK
| | - Jeremy I Skipper
- Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, UK
| | - Tessa M Dekker
- Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, UK
- Institute of Ophthalmology, University College London, London, UK
| |
Collapse
|
2
|
Cheron G, Ristori D, Petieau M, Simar C, Zarka D, Cebolla AM. Effects of Pulsed-Wave Chromotherapy and Guided Relaxation on the Theta-Alpha Oscillation During Arrest Reaction. Front Psychol 2022; 13:792872. [PMID: 35310269 PMCID: PMC8929400 DOI: 10.3389/fpsyg.2022.792872] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 01/13/2022] [Indexed: 12/31/2022] Open
Abstract
The search for the best wellness practice has promoted the development of devices integrating different technologies and guided meditation. However, the final effects on the electrical activity of the brain remain relatively sparse. Here, we have analyzed of the alpha and theta electroencephalographic oscillations during the realization of the arrest reaction (AR; eyes close/eyes open transition) when a chromotherapy session performed in a dedicated room [Rebalance (RB) device], with an ergonomic bed integrating pulsed-wave light (PWL) stimulation, guided breathing, and body scan exercises. We demonstrated that the PWL induced an evoked-related potential characterized by the N2-P3 components maximally recorded on the fronto-central areas and accompanied by an event-related synchronization (ERS) of the delta–theta–alpha oscillations. The power of the alpha and theta oscillations was analyzed during repeated ARs testing realized along with the whole RB session. We showed that the power of the alpha and theta oscillations was significantly increased during the session in comparison to their values recorded before. Of the 14 participants, 11 and 6 showed a significant power increase of the alpha and theta oscillations, respectively. These increased powers were not observed in two different control groups (n = 28) who stayed passively outside or inside the RB room but without any type of stimulation. These preliminary results suggest that PWL chromotherapy and guided relaxation induce measurable electrical brain changes that could be beneficial under neuropsychiatric perspectives.
Collapse
Affiliation(s)
- Guy Cheron
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium.,Laboratory of Neuroscience, Université de Mons, Mons, Belgium
| | - Dominique Ristori
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Mathieu Petieau
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Cédric Simar
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium.,Machine Learning Group, Computer Science Department, Université Libre de Bruxelles, Brussels, Belgium
| | - David Zarka
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| | - Ana-Maria Cebolla
- Laboratory of Neurophysiology and Movement Biomechanics, Université Libre de Bruxelles, Brussels, Belgium.,ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium
| |
Collapse
|
3
|
Campus C, Signorini S, Vitali H, De Giorgis V, Papalia G, Morelli F, Gori M. Sensitive period for the plasticity of alpha activity in humans. Dev Cogn Neurosci 2021; 49:100965. [PMID: 34051686 PMCID: PMC8167822 DOI: 10.1016/j.dcn.2021.100965] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/11/2021] [Accepted: 05/15/2021] [Indexed: 11/20/2022] Open
Abstract
Visual experience is crucial for the development of neural processing. For example, alpha activity development is a vision-dependent mechanism. Indeed, studies report no alpha activity is present in blind adults. Nevertheless, studies have not investigated the developmental trajectory of this activity in infants and children with blindness. Here, we hypothesize that the difference in neural activity of blind compared to sighted subjects is: absent at birth, progressive with age, specifically occipital and linked to a gradual motor impairment. Therefore, we consider spectral power of resting-state EEG and its association with motor impairment indices, in blind subjects and in sighted controls between 0 and 11 years of age. Blind subjects show posterior alpha activity during the first three years of life, although weaker and slower maturing compared to sighted subjects. The first great differentiation between blind and sighted subjects occurs between 3 and 6 years of age. Starting in this period, reduced alpha activity increases the probability of motor impairment in blind subjects, likely because of impaired perception/interaction. These results show that visual experience mediates the neural mechanisms generating alpha oscillations during the first years of life, suggesting that it is a sensitive period for the plasticity of this process.
Collapse
Affiliation(s)
- Claudio Campus
- U-VIP: Unit for Visually Impaired People, Istituto Italiano di Tecnologia, 16152, Genova, Italy
| | | | - Helene Vitali
- U-VIP: Unit for Visually Impaired People, Istituto Italiano di Tecnologia, 16152, Genova, Italy
| | | | | | | | - Monica Gori
- U-VIP: Unit for Visually Impaired People, Istituto Italiano di Tecnologia, 16152, Genova, Italy.
| |
Collapse
|
4
|
Zilio F, Gomez-Pilar J, Cao S, Zhang J, Zang D, Qi Z, Tan J, Hiromi T, Wu X, Fogel S, Huang Z, Hohmann MR, Fomina T, Synofzik M, Grosse-Wentrup M, Owen AM, Northoff G. Are intrinsic neural timescales related to sensory processing? Evidence from abnormal behavioral states. Neuroimage 2020; 226:117579. [PMID: 33221441 DOI: 10.1016/j.neuroimage.2020.117579] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/15/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
The brain exhibits a complex temporal structure which translates into a hierarchy of distinct neural timescales. An open question is how these intrinsic timescales are related to sensory or motor information processing and whether these dynamics have common patterns in different behavioral states. We address these questions by investigating the brain's intrinsic timescales in healthy controls, motor (amyotrophic lateral sclerosis, locked-in syndrome), sensory (anesthesia, unresponsive wakefulness syndrome), and progressive reduction of sensory processing (from awake states over N1, N2, N3). We employed a combination of measures from EEG resting-state data: auto-correlation window (ACW), power spectral density (PSD), and power-law exponent (PLE). Prolonged neural timescales accompanied by a shift towards slower frequencies were observed in the conditions with sensory deficits, but not in conditions with motor deficits. Our results establish that the spontaneous activity's intrinsic neural timescale is related to the neural capacity that specifically supports sensory rather than motor information processing in the healthy brain.
Collapse
Affiliation(s)
- Federico Zilio
- Department of Philosophy, Sociology, Education and Applied Psychology, University of Padova, Padua, Italy.
| | - Javier Gomez-Pilar
- Biomedical Engineering Group, University of Valladolid, Valladolid, Spain; Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Valladolid, Spain
| | - Shumei Cao
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jun Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Di Zang
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Zengxin Qi
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Jiaxing Tan
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Tanigawa Hiromi
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Xuehai Wu
- Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, China
| | - Stuart Fogel
- The Brain and Mind Institute, Department of Physiology and Pharmacology and the Department of Psychology, University of Western Ontario, Canada
| | - Zirui Huang
- Center for Consciousness Science, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Matthias R Hohmann
- Department for Empirical Inference, Max Planck Institute for Intelligent Systems, Tübingen, Germany
| | - Tatiana Fomina
- Department for Empirical Inference, Max Planck Institute for Intelligent Systems, Tübingen, Germany
| | - Matthis Synofzik
- Department of Neurology, Hertie Institute for Clinical Brain Research, Tübingen, Germany
| | - Moritz Grosse-Wentrup
- Research Group Neuroinformatics, Faculty of Computer Science, University of Vienna, Austria
| | - Adrian M Owen
- The Brain and Mind Institute, Department of Physiology and Pharmacology and the Department of Psychology, University of Western Ontario, Canada
| | - Georg Northoff
- Institute of Mental Health Research, University of Ottawa, Ottawa, Canada
| |
Collapse
|
5
|
Josipovic Z, Miskovic V. Nondual Awareness and Minimal Phenomenal Experience. Front Psychol 2020; 11:2087. [PMID: 32973628 PMCID: PMC7473343 DOI: 10.3389/fpsyg.2020.02087] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 07/28/2020] [Indexed: 01/09/2023] Open
Abstract
Minimal phenomenal experiences (MPEs) have recently gained attention in the fields of neuroscience and philosophy of mind. They can be thought of as episodes of greatly reduced or even absent phenomenal content together with a reduced level of arousal. It has also been proposed that MPEs are cases of consciousness-as-such. Here, we present a different perspective, that consciousness-as-such is first and foremost a type of awareness, that is, non-conceptual, non-propositional, and nondual, in other words, non-representational. This awareness is a unique kind and cannot be adequately specified by the two-dimensional model of consciousness as the arousal level plus the phenomenal content or by their mental representations. Thus, we suggest that to understand consciousness-as-such, and by extension consciousness in general, more accurately, we need to research it as a unique kind.
Collapse
Affiliation(s)
- Zoran Josipovic
- Department of Psychology, New York University, New York City, NY, United States
| | - Vladimir Miskovic
- Department of Psychology, Binghamton University, Binghamton, NY, United States
| |
Collapse
|
6
|
Paoletti P, Ben-Soussan TD. Reflections on Inner and Outer Silence and Consciousness Without Contents According to the Sphere Model of Consciousness. Front Psychol 2020; 11:1807. [PMID: 32903475 PMCID: PMC7435012 DOI: 10.3389/fpsyg.2020.01807] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/30/2020] [Indexed: 01/06/2023] Open
Abstract
In the current hypothesis paper, we propose that focusing attention on silence can be used as a paradigm conceptually similar to sensory deprivation, to study consciousness without content. We briefly overview recent influential models of consciousness and consider how they assess the relationship between consciousness and contents. After discussing the strengths and weaknesses of current models, we suggest an extension based on the Sphere Model of Consciousness (SMC) and introduce new definitions for identification and self-awareness as states of consciousness. We further compare Paoletti's theoretical model for the development of self with other influential models, highlighting similarities and differences. We conclude with a discussion of how attentional focus on silence can be empirically tested.
Collapse
Affiliation(s)
| | - Tal Dotan Ben-Soussan
- Research Institute for Neuroscience, Education and Didactics, Patrizio Paoletti Foundation, Assisi, Italy
| |
Collapse
|