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Krempel R, Monzel M. Aphantasia and involuntary imagery. Conscious Cogn 2024; 120:103679. [PMID: 38564857 DOI: 10.1016/j.concog.2024.103679] [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: 09/25/2023] [Revised: 03/06/2024] [Accepted: 03/09/2024] [Indexed: 04/04/2024]
Abstract
Aphantasia is a condition that is often characterized as the impaired ability to create voluntary mental images. Aphantasia is assumed to selectively affect voluntary imagery mainly because even though aphantasics report being unable to visualize something at will, many report having visual dreams. We argue that this common characterization of aphantasia is incorrect. Studies on aphantasia are often not clear about whether they are assessing voluntary or involuntary imagery, but some studies show that several forms of involuntary imagery are also affected in aphantasia (including imagery in dreams). We also raise problems for two attempts to show that involuntary images are preserved in aphantasia. In addition, we report the results of a study about afterimages in aphantasia, which suggest that these tend to be less intense in aphantasics than in controls. Involuntary imagery is often treated as a unitary kind that is either present or absent in aphantasia. We suggest that this approach is mistaken and that we should look at different types of involuntary imagery case by case. Doing so reveals no evidence of preserved involuntary imagery in aphantasia. We suggest that a broader characterization of aphantasia, as a deficit in forming mental imagery, whether voluntary or not, is more appropriate. Characterizing aphantasia as a volitional deficit is likely to lead researchers to give incorrect explanations for aphantasia, and to look for the wrong mechanisms underlying it.
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Affiliation(s)
- Raquel Krempel
- Center for Logic, Epistemology and History of Science, State University of Campinas, R. Sérgio Buarque de Holanda, 251 - Cidade Universitária, Campinas, SP 13083-859, Brazil; Center for Philosophy of Science, University of Pittsburgh, 4200 Fifth Ave, Pittsburgh, PA 15260, USA.
| | - Merlin Monzel
- Department of Psychology, Personality Psychology and Biological Psychology, University of Bonn, Kaiser-Karl-Ring 9, 53111 Bonn, Germany.
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Lacaux C, Strauss M, Bekinschtein TA, Oudiette D. Embracing sleep-onset complexity. Trends Neurosci 2024; 47:273-288. [PMID: 38519370 DOI: 10.1016/j.tins.2024.02.002] [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: 09/06/2023] [Revised: 01/17/2024] [Accepted: 02/07/2024] [Indexed: 03/24/2024]
Abstract
Sleep is crucial for many vital functions and has been extensively studied. By contrast, the sleep-onset period (SOP), often portrayed as a mere prelude to sleep, has been largely overlooked and remains poorly characterized. Recent findings, however, have reignited interest in this transitional period and have shed light on its neural mechanisms, cognitive dynamics, and clinical implications. This review synthesizes the existing knowledge about the SOP in humans. We first examine the current definition of the SOP and its limits, and consider the dynamic and complex electrophysiological changes that accompany the descent to sleep. We then describe the interplay between internal and external processing during the wake-to-sleep transition. Finally, we discuss the putative cognitive benefits of the SOP and identify novel directions to better diagnose sleep-onset disorders.
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Affiliation(s)
- Célia Lacaux
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland; Institut du Cerveau (Paris Brain Institute), Institut du Cerveau et de la Moelle Épinière (ICM), Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Paris 75013, France.
| | - Mélanie Strauss
- Neuropsychology and Functional Neuroimaging Research Group (UR2NF), Center for Research in Cognition and Neurosciences (CRCN), Université Libre de Bruxelles, B-1050 Brussels, Belgium; Departments of Neurology, Psychiatry, and Sleep Medicine, Hôpital Universitaire de Bruxelles, Site Erasme, Université Libre de Bruxelles, B-1070 Brussels, Belgium
| | - Tristan A Bekinschtein
- Cambridge Consciousness and Cognition Laboratory, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK
| | - Delphine Oudiette
- Institut du Cerveau (Paris Brain Institute), Institut du Cerveau et de la Moelle Épinière (ICM), Institut National de la Santé et de la Recherche Médicale (INSERM), Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Paris 75013, France; Assistance Publique - Hopitaux de Paris (AP-HP), Hôpital Pitié-Salpêtrière, Service des Pathologies du Sommeil, National Reference Centre for Narcolepsy, Paris 75013, France.
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García-Bermúdez M, Pampillón-Albert M, Santos-Bueso E. [Hypnopompic hallucinations and the sleep apnea-hypopnea syndrome]. Med Clin (Barc) 2024; 162:305-306. [PMID: 38036332 DOI: 10.1016/j.medcli.2023.09.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 09/22/2023] [Accepted: 09/27/2023] [Indexed: 12/02/2023]
Affiliation(s)
| | | | - Enrique Santos-Bueso
- Servicio de Oftalmología, Hospital Universitario Clínico San Carlos, Madrid, España
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Incekara F, Blom JD. Carl Jung: a life on the edge of reality with hypnagogia, hyperphantasia, and hallucinations. Front Psychol 2024; 15:1358329. [PMID: 38515975 PMCID: PMC10954828 DOI: 10.3389/fpsyg.2024.1358329] [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: 12/19/2023] [Accepted: 02/13/2024] [Indexed: 03/23/2024] Open
Abstract
Whether the Swiss psychiatrist Carl Jung (1875-1961) became psychotic after his mid-thirties is much debated. His recently published Black Books, a seven-volume journal, reveal new insights into this debate. Based on a phenomenological analysis of his self-reports in these books and in other writings, we here identify several types of anomalous perceptual experiences: hypnagogic-hypnopompic experiences, hyperphantasia, hallucinations, personifications, and sensed presence. We argue that these experiences were not indicative of a psychotic disorder, but rather stemmed from extremely vivid mental imagery, or hyperphantasia, a condition Jung's contemporaries and later biographers were unable to take into account because it had not yet been conceptualised. Recently, the degree of vividness of mental imagery and its potential to become indistinguishable from regular sense perception has been the subject of extensive studies. Unknowingly, Jung may have foreshadowed this line of research with his psychoanalytic concept of reality equivalence, i.e., the substitution of an external world for an inner mental reality that he encountered in individuals diagnosed with schizophrenia. There is a need for future research to investigate the possible role of hyperphantasia in psychotic experiences, but to Jung, psychosis was 'a failure to contain and comprehend' the content of one's experiences in the context of one's own life, whereas he himself did manage to put the content of his perceptual experiences into context, to find meaning in them, and to share them with others - to great acknowledgement and acclaim.
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Affiliation(s)
| | - Jan Dirk Blom
- Parnassia Psychiatric Institute, The Hague, Netherlands
- Faculty of Social and Behavioural Sciences, Leiden University, Leiden, Netherlands
- Department of Psychiatry, University Medical Centre Groningen, Groningen, Netherlands
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Foffani G. To be or not to be hallucinating: Implications of hypnagogic/hypnopompic experiences and lucid dreaming for brain disorders. PNAS NEXUS 2024; 3:pgad442. [PMID: 38178978 PMCID: PMC10766414 DOI: 10.1093/pnasnexus/pgad442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 12/06/2023] [Indexed: 01/06/2024]
Abstract
The boundaries between waking and sleeping-when falling asleep (hypnagogic) or waking up (hypnopompic)-can be challenging for our ability to monitor and interpret reality. Without proper understanding, bizarre but relatively normal hypnagogic/hypnopompic experiences can be misinterpreted as psychotic hallucinations (occurring, by definition, in the fully awake state), potentially leading to stigma and misdiagnosis in clinical contexts and to misconception and bias in research contexts. This Perspective proposes that conceptual and practical understanding for differentiating hallucinations from hypnagogic/hypnopompic experiences may be offered by lucid dreaming, the state in which one is aware of dreaming while sleeping. I first introduce a possible systematization of the phenomenological range of hypnagogic/hypnopompic experiences that can occur in the transition from awake to REM dreaming (including hypnagogic perceptions, transition symptoms, sleep paralysis, false awakenings, and out-of-body experiences). I then outline how metacognitive strategies used by lucid dreamers to gain/confirm oneiric lucidity could be tested for better differentiating hypnagogic/hypnopompic experiences from hallucinations. The relevance of hypnagogic/hypnopompic experiences and lucid dreaming is analyzed for schizophrenia and narcolepsy, and discussed for neurodegenerative diseases, particularly Lewy-body disorders (i.e. Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies), offering testable hypotheses for empirical investigation. Finally, emotionally positive lucid dreams triggered or enhanced by training/induction strategies or by a pathological process may have intrinsic therapeutic value if properly recognized and guided. The overall intention is to raise awareness and foster further research about the possible diagnostic, prognostic, and therapeutic implications of hypnagogic/hypnopompic experiences and lucid dreaming for brain disorders.
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Affiliation(s)
- Guglielmo Foffani
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid 28938, Spain
- Hospital Nacional de Parapléjicos, Toledo 45004, Spain
- CIBERNED, Instituto de Salud Carlos III, Madrid 28031, Spain
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Vickrey B, Lerner I. Overnight exposure to pink noise could jeopardize sleep-dependent insight and pattern detection. Front Hum Neurosci 2023; 17:1302836. [PMID: 38107593 PMCID: PMC10722168 DOI: 10.3389/fnhum.2023.1302836] [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: 09/27/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023] Open
Abstract
Accumulated evidence from the past decades suggests that sleep plays a crucial role in memory consolidation and the facilitation of higher-level cognitive processes such as abstraction and gist extraction. In addition, recent studies show that applying pink noise during sleep can further enhance sleep-dependent memory consolidation, potentially by modulating sleep physiology through stochastic resonance. However, whether this enhancement extends to higher cognitive processes remains untested. In this study, we investigated how the application of open-loop pink noise during sleep influences the gain of insight into hidden patterns. Seventy-two participants were assigned to three groups: daytime-wake, silent sleep, and sleep with pink noise. Each group completed the number reduction task, an established insight paradigm known to be influenced by sleep, over two sessions with a 12-h interval. Sleep groups were monitored by the DREEM 3 headband in home settings. Contrary to our prediction, pink noise did not induce an increase in insight compared to silent sleep and was statistically more similar to the wake condition despite evidence for its typical influence on sleep physiology. Particularly, we found that pink noise limited the time spent in the initial cycle of N1 just after sleep onset, while time spent in N1 positively predicted insight. These results echo recent suggestions that the time in the initial cycle of N1 plays a critical role in insight formation. Overall, our results suggest that open-loop pink noise during sleep may be detrimental to insight formation and creativity due to the alterations it causes to normal sleep architecture.
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Affiliation(s)
- Beverly Vickrey
- Department of Psychology, The University of Texas at San Antonio, San Antonio, TX, United States
| | - Itamar Lerner
- Department of Psychology, The University of Texas at San Antonio, San Antonio, TX, United States
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Ghibellini R, Meier B. Hypnagogic states are quite common: Self-reported prevalence, modalities, and gender differences. Conscious Cogn 2023; 115:103582. [PMID: 37812995 DOI: 10.1016/j.concog.2023.103582] [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: 04/27/2023] [Revised: 09/20/2023] [Accepted: 09/27/2023] [Indexed: 10/11/2023]
Abstract
The hypnagogic state refers to the transitional phase between wakefulness and sleep during which vivid experiences occur. In this questionnaire study, we assessed the self-reported prevalence of hypnagogic states considering the frequency of experiences in different modalities. We also assessed the emotional quality and the vividness of the experiences. Moreover, we compared hypnagogic states to other phenomena, such as dreams, sleep paralysis, imagination, and extra-sensory perception in these measures. Hypnagogic states were reported by 80.2 % of 4456 participants and were more prevalent in women than men. Experiences were most often kinaesthetic and visual, and less often auditory, tactile, and olfactory or gustatory. Hypnagogic states were less prevalent than dreams and characterized by different modality profiles. However, they were similar to dreams in their emotional quality, the irritation they caused, and in their vividness. In conclusion, hypnagogic states are quite common.
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Affiliation(s)
| | - Beat Meier
- Institute of Psychology, University of Bern, Switzerland
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Lopez R, Micoulaud-Franchi JA, Peter-Derex L, Dauvilliers Y. Nocturnal agitation: From sleep state dissociation to sleep-related dissociative state. Rev Neurol (Paris) 2023; 179:675-686. [PMID: 37625976 DOI: 10.1016/j.neurol.2023.07.003] [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: 07/20/2023] [Revised: 07/26/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023]
Abstract
Nocturnal agitation refers to a broad spectrum of symptoms from simple movements to aggressive behaviors with partial or complete loss of awareness. An accurate identification of its etiology is critical for appropriate therapeutic intervention. In children and young adults, distinguishing between non-rapid eye movement (NREM) sleep parasomnias and psychogenic non-parasomniac manifestations, a condition known as sleep-related dissociative disorder (SRDD), can be challenging. This review aims to summarize current clinical, neurophysiological, and epidemiological knowledge on NREM parasomnia and SRDD, and to present the pathophysiological hypotheses underlying these nocturnal manifestations. Sleepwalking, sleep terror and confusional arousals are the three main presentations of NREM parasomnias and share common clinical characteristics. Parasomniac episodes generally occur 30minutes to three hours after sleep-onset, they are usually short, lasting no more than few minutes and involve non-stereotyped, clumsy behaviors with frequent amnesia. The prevalence of NREM parasomnia decreases from 15-30% in children to 2-4% in adults. Parasomniac episodes are incomplete awakening from the deepest NREM sleep and are characterized by a dissociated brain activity, with a wake-like activation in motor and limbic structures and a preserved sleep in the fronto-parietal regions. SRDD is a less known condition characterized by dramatic, often very long episodes with frequent aggressive and potentially dangerous behaviors. SRDD episodes frequently occur in quiet wakefulness before falling asleep. These dissociative manifestations are frequently observed in the context of psychological trauma. The pathophysiology of SRDD is poorly understood but could involve transient changes in brain connectivity due to labile sleep-wake boundaries in predisposed individuals. We hypothesize that SRDD and NREM parasomnia are forms of sleep-related dissociative states favored by a sleep-wake state dissociation during sleep-onset and awakening process, respectively.
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Affiliation(s)
- R Lopez
- National Reference Centre for Orphan Diseases, Narcolepsy-Rare hypersomnias, Sleep Unit, Department of Neurology, CHU de Montpellier, University of Montpellier, Montpellier, France; Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, Montpellier, France.
| | - J-A Micoulaud-Franchi
- Service Universitaire de médecine du Sommeil, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France; UMR CNRS 6033 SANPSY, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France
| | - L Peter-Derex
- Center for Sleep Medicine and Respiratory Diseases, Croix-Rousse Hospital, Hospices Civils de Lyon, Lyon 1 University, Lyon, France; Lyon Neuroscience Research Center, PAM Team, Inserm U1028, CNRS UMR 5292, Lyon, France
| | - Y Dauvilliers
- National Reference Centre for Orphan Diseases, Narcolepsy-Rare hypersomnias, Sleep Unit, Department of Neurology, CHU de Montpellier, University of Montpellier, Montpellier, France; Institute for Neurosciences of Montpellier (INM), University of Montpellier, Inserm, Montpellier, France
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