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Tononi G, Boly M, Cirelli C. Consciousness and sleep. Neuron 2024; 112:1568-1594. [PMID: 38697113 PMCID: PMC11105109 DOI: 10.1016/j.neuron.2024.04.011] [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: 03/07/2024] [Revised: 04/04/2024] [Accepted: 04/10/2024] [Indexed: 05/04/2024]
Abstract
Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, WI 53719, USA
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA
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2
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Hudachek L, Wamsley EJ. A meta-analysis of the relation between dream content and memory consolidation. Sleep 2023; 46:zsad111. [PMID: 37058584 DOI: 10.1093/sleep/zsad111] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Revised: 03/11/2023] [Indexed: 04/16/2023] Open
Abstract
The frequent appearance of newly learned information in dreams suggests that dream content is influenced by memory consolidation. Many studies have tested this hypothesis by asking whether dreaming about a learning task is associated with improved memory, but results have been inconsistent. We conducted a meta-analysis to determine the strength of the association between learning-related dreams and post-sleep memory improvement. We searched the literature for studies that (1) trained participants on a pre-sleep learning task and then tested their memory after sleep, and (2) associated post-sleep memory improvement with the extent to which dreams incorporated learning task content. Sixteen studies qualified for inclusion, which together reported 45 effects. Integrating across effects, we report a strong and statistically significant association between task-related dreaming and memory performance (SMD = 0.51 [95% CI 0.28, 0.74], p < 0.001). Among studies using polysomnography, this relationship was statistically significant for dreams collected from non-rapid eye movement (NREM) sleep (n = 10) but not for dreams collected from rapid eye movement (REM) sleep (n = 12). There was a significant association between dreaming and memory for all types of learning tasks studied. This meta-analysis provides further evidence that dreaming about a learning task is associated with improved memory performance, suggesting that dream content may be an indication of memory consolidation. Furthermore, we report preliminary evidence that the relationship between dreaming and memory may be stronger in NREM sleep compared to REM.
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Affiliation(s)
- Lauren Hudachek
- Furman University Department of Psychology and Program in Neuroscience, Greenville, SC, 29613, USA
| | - Erin J Wamsley
- Furman University Department of Psychology and Program in Neuroscience, Greenville, SC, 29613, USA
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3
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Picard-Deland C, Konkoly K, Raider R, Paller KA, Nielsen T, Pigeon WR, Carr M. The memory sources of dreams: serial awakenings across sleep stages and time of night. Sleep 2023; 46:zsac292. [PMID: 36462190 PMCID: PMC10091095 DOI: 10.1093/sleep/zsac292] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/27/2022] [Indexed: 12/05/2022] Open
Abstract
Memories of waking-life events are incorporated into dreams, but their incorporation is not uniform across a night of sleep. This study aimed to elucidate ways in which such memory sources vary by sleep stage and time of night. Twenty healthy participants (11 F; 24.1 ± 5.7 years) spent a night in the laboratory and were awakened for dream collection approximately 12 times spread across early, middle, and late periods of sleep, while covering all stages of sleep (N1, N2, N3, REM). In the morning, participants identified and dated associated memories of waking-life events for each dream report, when possible. The incorporation of recent memory sources in dreams was more frequent in N1 and REM than in other sleep stages. The incorporation of distant memories from over a week ago, semantic memories not traceable to a single event, and anticipated future events remained stable throughout sleep. In contrast, the relative proportions of recent versus distant memory sources changed across the night, independently of sleep stage, with late-night dreams in all stages having relatively less recent and more remote memory sources than dreams earlier in the night. Qualitatively, dreams tended to repeat similar themes across the night and in different sleep stages. The present findings clarify the temporal course of memory incorporations in dreams, highlighting a specific connection between time of night and the temporal remoteness of memories. We discuss how dream content may, at least in part, reflect the mechanisms of sleep-dependent memory consolidation.
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Affiliation(s)
| | - Karen Konkoly
- Department of Psychology, Northwestern University, Evanston, IL, USA
| | - Rachel Raider
- Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, USA
| | - Ken A Paller
- Department of Psychology, Northwestern University, Evanston, IL, USA
| | - Tore Nielsen
- Department of Psychiatry and Addictology, University of Montreal, Montreal, Quebec, Canada
| | - Wilfred R Pigeon
- Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, USA
| | - Michelle Carr
- Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, USA
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4
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Simor P, Peigneux P, Bódizs R. Sleep and dreaming in the light of reactive and predictive homeostasis. Neurosci Biobehav Rev 2023; 147:105104. [PMID: 36804397 DOI: 10.1016/j.neubiorev.2023.105104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/07/2023] [Accepted: 02/16/2023] [Indexed: 02/19/2023]
Abstract
Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes.
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Affiliation(s)
- Péter Simor
- Institute of Psychology, ELTE, Eötvös Loránd University, Budapest, Hungary; UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Philippe Peigneux
- UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Róbert Bódizs
- Institute of Behavioural Sciences, Semmelweis University, Budapest, Hungary.
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5
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Chavda V, Chaurasia B, Umana GE, Tomasi SO, Lu B, Montemurro N. Narcolepsy-A Neuropathological Obscure Sleep Disorder: A Narrative Review of Current Literature. Brain Sci 2022; 12:1473. [PMID: 36358399 PMCID: PMC9688775 DOI: 10.3390/brainsci12111473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/22/2022] [Accepted: 10/28/2022] [Indexed: 08/29/2023] Open
Abstract
Narcolepsy is a chronic, long-term neurological disorder characterized by a decreased ability to regulate sleep-wake cycles. Some clinical symptoms enter into differential diagnosis with other neurological diseases. Excessive daytime sleepiness and brief involuntary sleep episodes are the main clinical symptoms. The majority of people with narcolepsy experience cataplexy, which is a loss of muscle tone. Many people experience neurological complications such as sleep cycle disruption, hallucinations or sleep paralysis. Because of the associated neurological conditions, the exact pathophysiology of narcolepsy is unknown. The differential diagnosis is essential because relatively clinical symptoms of narcolepsy are easy to diagnose when all symptoms are present, but it becomes much more complicated when sleep attacks are isolated and cataplexy is episodic or absent. Treatment is tailored to the patient's symptoms and clinical diagnosis. To facilitate the diagnosis and treatment of sleep disorders and to better understand the neuropathological mechanisms of this sleep disorder, this review summarizes current knowledge on narcolepsy, in particular, genetic and non-genetic associations of narcolepsy, the pathophysiology up to the inflammatory response, the neuromorphological hallmarks of narcolepsy, and possible links with other diseases, such as diabetes, ischemic stroke and Alzheimer's disease. This review also reports all of the most recent updated research and therapeutic advances in narcolepsy. There have been significant advances in highlighting the pathogenesis of narcolepsy, with substantial evidence for an autoimmune response against hypocretin neurons; however, there are some gaps that need to be filled. To treat narcolepsy, more research should be focused on identifying molecular targets and novel autoantigens. In addition to therapeutic advances, standardized criteria for narcolepsy and diagnostic measures are widely accepted, but they may be reviewed and updated in the future with comprehension. Tailored treatment to the patient's symptoms and clinical diagnosis and future treatment modalities with hypocretin agonists, GABA agonists, histamine receptor antagonists and immunomodulatory drugs should be aimed at addressing the underlying cause of narcolepsy.
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Affiliation(s)
- Vishal Chavda
- Department of Pathology, Stanford of School of Medicine, Stanford University Medical Centre, Palo Alto, CA 94305, USA
| | - Bipin Chaurasia
- Department of Neurosurgery, Neurosurgery Clinic, Birgunj 44300, Nepal
| | - Giuseppe E. Umana
- Department of Neurosurgery, Associate Fellow of American College of Surgeons, Trauma and Gamma-Knife Centre, Cannizzaro Hospital Catania, 95100 Catania, Italy
| | | | - Bingwei Lu
- Department of Pathology, Stanford of School of Medicine, Stanford University Medical Centre, Palo Alto, CA 94305, USA
| | - Nicola Montemurro
- Department of Neurosurgery, Azienda Ospedaliera Universitaria Pisana (AOUP), University of Pisa, 56100 Pisa, Italy
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6
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Scarpelli S, Alfonsi V, Gorgoni M, De Gennaro L. What about dreams? State of the art and open questions. J Sleep Res 2022; 31:e13609. [PMID: 35417930 PMCID: PMC9539486 DOI: 10.1111/jsr.13609] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 03/28/2022] [Accepted: 03/28/2022] [Indexed: 02/05/2023]
Abstract
Several studies have tried to identify the neurobiological bases of dream experiences, nevertheless some questions are still at the centre of the debate. Here, we summarise the main open issues concerning the neuroscientific study of dreaming. After overcoming the rapid eye movement (REM) ‐ non‐REM (NREM) sleep dichotomy, investigations have focussed on the specific functional or structural brain features predicting dream experience. On the one hand, some results underlined that specific trait‐like factors are associated with higher dream recall frequency. On the other hand, the electrophysiological milieu preceding dream report upon awakening is a crucial state‐like factor influencing the subsequent recall. Furthermore, dreaming is strictly related to waking experiences. Based on the continuity hypothesis, some findings reveal that dreaming could be modulated through visual, olfactory, or somatosensory stimulations. Also, it should be considered that the indirect access to dreaming remains an intrinsic limitation. Recent findings have revealed a greater concordance between parasomnia‐like events and dream contents. This means that parasomnia episodes might be an expression of the ongoing mental sleep activity and could represent a viable direct access to dream experience. Finally, we provide a picture on nightmares and emphasise the possible role of oneiric activity in psychotherapy. Overall, further efforts in dream science are needed (a) to develop a uniform protocol to study dream experience, (b) to introduce and integrate advanced techniques to better understand whether dreaming can be manipulated, (c) to clarify the relationship between parasomnia events and dreaming, and (d) to determine the clinical valence of dreams.
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Affiliation(s)
- Serena Scarpelli
- Department of Psychology, Sapienza University of Rome, Rome, Italy
| | | | - Maurizio Gorgoni
- Department of Psychology, Sapienza University of Rome, Rome, Italy.,Body and Action Lab, IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Luigi De Gennaro
- Department of Psychology, Sapienza University of Rome, Rome, Italy.,Body and Action Lab, IRCCS Fondazione Santa Lucia, Rome, Italy
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7
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Raduga M. Detecting lucid dreams only by submentalis electromyography. Sleep Med 2021; 88:221-230. [PMID: 34798438 DOI: 10.1016/j.sleep.2021.10.030] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 11/17/2022]
Abstract
Lucid dreams (LDs) occur when people become aware that they are dreaming. This phenomenon has a wide range of possible applications from the perspectives of psychology, training physical movements, and controlling computers while asleep, among others. However, research on LDs might lack efficiency because the standard LD verification protocol uses polysomnography (PSG), which requires an expensive apparatus and skilled staff. The standard protocol also may reduce LD-induction efficiency. The current study examines whether humans can send phasic signals through submentalis electromyography (EMG) during muscle atonia via pre-agreed chin movements (PACM). This ability would manifest both REM sleep and consciousness, which are the main features of LDs. In laboratory conditions volunteers were instructed to open their jaws three times while in an LD right after the standard verification protocol to achieve the research goal. Results: 4 of 5 volunteers proved to be in an LD using the standard protocol, and then all of them made PACM. The outcomes show that dream signals cannot be blocked in the submentalis area during muscle atonia. Also, this finding can be considered to develop a simplified, reliable LD protocol that needs only one EMG sensor. The cost of this protocol could be only a small percentage of the current protocol, making it more convenient for researchers and volunteers. It can also be used remotely by inbuilt in wearable gadgets. Considering PACM could speed up LD research and provide many discoveries and new opportunities. Also, it can be used in sleep paralysis studies.
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8
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de la Chapelle A, Frauscher B, Valomon A, Ruby PM, Peter-Derex L. Relationship Between Epilepsy and Dreaming: Current Knowledge, Hypotheses, and Perspectives. Front Neurosci 2021; 15:717078. [PMID: 34552464 PMCID: PMC8451887 DOI: 10.3389/fnins.2021.717078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 08/16/2021] [Indexed: 11/13/2022] Open
Abstract
The interactions between epilepsy and sleep are numerous and the impact of epilepsy on cognition is well documented. Epilepsy is therefore likely to influence dreaming as one sleep-related cognitive activity. The frequency of dream recall is indeed decreased in patients with epilepsy, especially in those with primary generalized seizures. The content of dreams is also disturbed in epilepsy patients, being more negative and with more familiar settings. While several confounding factors (anti-seizure medications, depression and anxiety disorders, cognitive impairment) may partly account for these changes, some observations suggest an effect of seizures themselves on dreams. Indeed, the incorporation of seizure symptoms in dream content has been described, concomitant or not with a focal epileptic discharge during sleep, suggesting that epilepsy might directly or indirectly interfere with dreaming. These observations, together with current knowledge on dream neurophysiology and the links between epilepsy and sleep, suggest that epilepsy may impact not only wake- but also sleep-related cognition.
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Affiliation(s)
| | - Birgit Frauscher
- Analytical Neurophysiology Lab, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Amandine Valomon
- Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028-PAM Team, Lyon, France
| | - Perrine Marie Ruby
- Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028-PAM Team, Lyon, France
| | - Laure Peter-Derex
- Lyon Neuroscience Research Center, CNRS UMR 5292, INSERM U1028-PAM Team, Lyon, France.,Center for Sleep Medicine and Respiratory Diseases, Lyon University Hospital, Lyon 1 University, Lyon, France
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9
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Krishnan D. Orchestration of dreams: a possible tool for enhancement of mental productivity and efficiency. Sleep Biol Rhythms 2021; 19:207-213. [PMID: 33526967 PMCID: PMC7839624 DOI: 10.1007/s41105-021-00313-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/15/2021] [Indexed: 11/29/2022]
Abstract
Deciphering the significance of dreams, remains a dream till date. A little is known about its underlying mechanism, brain regions involved and implications with wake life. This review is aimed to investigate the latest developments to summarize the differences in nature of dreams in Rapid eye movement and Non rapid eye movement sleep, possible role of dreams in day to day life with larger focus on Lucid Dreaming- its significant role in elevating productivity and efficiency. To carry out this review, combination of keywords like Lucid Dreaming, Rapid eye movement, Non rapid eye movement, Sleep Cycle, Dream Patterns, molecular mechanism of dreaming etc. were entered in databases like National library of Medicine, Google Scholar etc. Nature and composition of dreams are distinct in different sleep phases and it tends to influence cognitive skills, memory consolidation, mood and personal temperaments. It was observed that dreams in distinct phases, can be directly/indirectly related to development of cognition, skill enhancements, learning, healing, and even stress management affecting overall performance and productivity of an individual. Understanding the nature of dream contents in different phases can possibly inculcate insights for not only recovery aid in several mental illnesses but for elevated efficiency and productivity in normal individuals as well. Realising dreams as an effective tool for its contribution in daily activities might help organising our mood and overall mental well-being, a foremost component to thrive in the contemporary world which is currently undergoing the chaos of Novel Coronavirus Disease 2019.
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Affiliation(s)
- Dolly Krishnan
- Westfälische Wilhelms-Universität Münster, Münster, Germany
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10
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Vallat R, Nicolas A, Ruby P. Brain functional connectivity upon awakening from sleep predicts interindividual differences in dream recall frequency. Sleep 2020; 43:5864676. [PMID: 32597973 DOI: 10.1093/sleep/zsaa116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 05/14/2020] [Indexed: 12/28/2022] Open
Abstract
Why do some individuals recall dreams every day while others hardly ever recall one? We hypothesized that sleep inertia-the transient period following awakening associated with brain and cognitive alterations-could be a key mechanism to explain interindividual differences in dream recall at awakening. To test this hypothesis, we measured the brain functional connectivity (combined electroencephalography-functional magnetic resonance imaging) and cognition (memory and mental calculation) of high dream recallers (HR, n = 20) and low dream recallers (LR, n = 18) in the minutes following awakening from an early-afternoon nap. Resting-state scans were acquired just after or before a 2 min mental calculation task, before the nap, 5 min after awakening from the nap, and 25 min after awakening. A comic was presented to the participants before the nap with no explicit instructions to memorize it. Dream(s) and comic recall were collected after the first post-awakening scan. As expected, between-group contrasts of the functional connectivity at 5 min post-awakening revealed a pattern of enhanced connectivity in HR within the default mode network (DMN) and between regions of the DMN and regions involved in memory processes. At the behavioral level, a between-group difference was observed in dream recall, but not comic recall. Our results provide the first evidence that brain functional connectivity right after awakening is associated with interindividual trait differences in dream recall and suggest that the brain connectivity of HR at awakening facilitates the maintenance of the short-term memory of the dream during the sleep-wake transition.
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Affiliation(s)
- Raphael Vallat
- Department of Psychology, Center for Human Sleep Science, University of California, Berkeley, CA.,Lyon Neuroscience Research Center (CRNL), Brain Dynamics and Cognition team (DYCOG), INSERM UMRS 1028, CNRS UMR 5292, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | - Alain Nicolas
- Lyon Neuroscience Research Center (CRNL), Brain Dynamics and Cognition team (DYCOG), INSERM UMRS 1028, CNRS UMR 5292, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
| | - Perrine Ruby
- Lyon Neuroscience Research Center (CRNL), Brain Dynamics and Cognition team (DYCOG), INSERM UMRS 1028, CNRS UMR 5292, Université Claude Bernard Lyon 1, Université de Lyon, Lyon, France
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11
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Nicolas A, Ruby PM. Dreams, Sleep, and Psychotropic Drugs. Front Neurol 2020; 11:507495. [PMID: 33224081 PMCID: PMC7674595 DOI: 10.3389/fneur.2020.507495] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 09/28/2020] [Indexed: 02/04/2023] Open
Abstract
Over the past 60 years, the impact of psychotropic drugs on dream recall and content has been scarcely explored. A review of the few existing experimental results on the topic leads us to the following conclusions. For antidepressant drugs, in the great majority, they reduce dream recall frequency (DRF), and the improvement of depressive symptoms is associated with an increase of positive emotion in dream content. For sedative psychotropic drugs, their improvement of sleep quality is associated with a reduction of DRF, but the effect on dream content is less clear. Few occurrences of nightmare frequency increase have been reported, with intake of molecules disturbing sleep or with the withdrawal of some psychotropic drugs. Importantly, the impact of psychotropic drugs on rapid eye movement (REM) sleep does not explain DRF modulations. The reduction of intra-sleep awakenings seems to be the parameter explaining best the modulation of DRF by psychotropic drugs. Indeed, molecules that improve sleep continuity by reducing intra-sleep awakenings also reduce the frequency of dream recall, which is coherent with the “arousal-retrieval model” stating that nighttime awakenings enable dreams to be encoded into long-term memory and therefore facilitate dream recall. DRF is nonetheless influenced by several other factors (e.g., interest in dreams, the method of awakening, and personality traits), which may explain a large part of the variability of results observed and cited in this article.
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Affiliation(s)
- Alain Nicolas
- Lyon Neuroscience Research Center, CNRS UMR 5292 - INSERM U1028 - Lyon 1 University, Lyon, France
| | - Perrine M Ruby
- Lyon Neuroscience Research Center, CNRS UMR 5292 - INSERM U1028 - Lyon 1 University, Lyon, France
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12
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Carr M, Haar A, Amores J, Lopes P, Bernal G, Vega T, Rosello O, Jain A, Maes P. Dream engineering: Simulating worlds through sensory stimulation. Conscious Cogn 2020; 83:102955. [PMID: 32652511 PMCID: PMC7415562 DOI: 10.1016/j.concog.2020.102955] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 04/19/2020] [Accepted: 05/18/2020] [Indexed: 01/14/2023]
Abstract
We explore the application of a wide range of sensory stimulation technologies to the area of sleep and dream engineering. We begin by emphasizing the causal role of the body in dream generation, and describe a circuitry between the sleeping body and the dreaming mind. We suggest that nearly any sensory stimuli has potential for modulating experience in sleep. Considering other areas that might afford tools for engineering sensory content in simulated worlds, we turn to Virtual Reality (VR). We outline a collection of relevant VR technologies, including devices engineered to stimulate haptic, temperature, vestibular, olfactory, and auditory sensations. We believe these technologies, which have been developed for high mobility and low cost, can be translated to the field of dream engineering. We close by discussing possible future directions in this field and the ethics of a world in which targeted dream direction and sleep manipulation are feasible.
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Affiliation(s)
- Michelle Carr
- Sleep & Neurophysiology Research Laboratory, Department of Psychiatry, University of Rochester Medical Center, Rochester, NY, USA.
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13
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Scarpelli S, D’Atri A, Bartolacci C, Gorgoni M, Mangiaruga A, Ferrara M, De Gennaro L. Dream Recall upon Awakening from Non-Rapid Eye Movement Sleep in Older Adults: Electrophysiological Pattern and Qualitative Features. Brain Sci 2020; 10:E343. [PMID: 32503215 PMCID: PMC7349242 DOI: 10.3390/brainsci10060343] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 02/05/2023] Open
Abstract
Several findings support the activation hypothesis, positing that cortical arousal promotes dream recall (DR). However, most studies have been carried out on young participants, while the electrophysiological (EEG) correlates of DR in older people are still mostly unknown. We aimed to test the activation hypothesis on 20 elders, focusing on the Non-Rapid Eye Movement (NREM) sleep stage. All the subjects underwent polysomnography, and a dream report was collected upon their awakening from NREM sleep. Nine subjects were recallers (RECs) and 11 were non-RECs (NRECs). The delta and beta EEG activity of the last 5 min and the total NREM sleep was calculated by Fast Fourier Transform. Statistical comparisons (RECs vs. NRECs) revealed no differences in the last 5 min of sleep. Significant differences were found in the total NREM sleep: the RECs showed lower delta power over the parietal areas than the NRECs. Consistently, statistical comparisons on the activation index (delta/beta power) revealed that RECs showed a higher level of arousal in the fronto-temporal and parieto-occipital regions than NRECs. Both visual vividness and dream length are positively related to the level of activation. Overall, our results are consistent with the view that dreaming and the storage of oneiric contents depend on the level of arousal during sleep, highlighting a crucial role of the temporo-parietal-occipital zone.
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Affiliation(s)
- Serena Scarpelli
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy;
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
| | - Aurora D’Atri
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
| | - Chiara Bartolacci
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
| | - Maurizio Gorgoni
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
| | - Anastasia Mangiaruga
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
- Department of Medical and Surgical Sciences (DIMEC), University of Bologna, 40126 Bologna, Italy
| | - Michele Ferrara
- Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, Via Vetoio (Coppito 2), 67100 Coppito (L’Aquila), Italy;
| | - Luigi De Gennaro
- IRCCS Fondazione Santa Lucia, 00179 Rome, Italy;
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (A.D.); (C.B.); (M.G.); (A.M.)
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14
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Libourel PA, Barrillot B. Is there REM sleep in reptiles? A key question, but still unanswered. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.01.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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15
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Daytime sleep state misperception in a tertiary sleep centre population. Sleep Med 2020; 69:78-84. [DOI: 10.1016/j.sleep.2019.12.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/13/2019] [Accepted: 12/27/2019] [Indexed: 12/22/2022]
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16
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Mota-Rolim SA. On Moving the Eyes to Flag Lucid Dreaming. Front Neurosci 2020; 14:361. [PMID: 32351360 PMCID: PMC7174658 DOI: 10.3389/fnins.2020.00361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 03/24/2020] [Indexed: 01/02/2023] Open
Affiliation(s)
- Sergio Arthuro Mota-Rolim
- Brain Institute, Department of Physiology and Behavior, and Onofre Lopes University Hospital - Federal University of Rio Grande Do Norte, Natal, Brazil
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17
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Ledard N, Artru E, Colmenarez Sayago P, Redolfi S, Golmard JL, Carrillo-Solano M, Arnulf I. Adrenergic reactions during N3 sleep arousals in sleepwalking and sleep terrors: The chicken or the egg? J Sleep Res 2019; 29:e12946. [PMID: 31742835 DOI: 10.1111/jsr.12946] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 10/03/2019] [Accepted: 10/17/2019] [Indexed: 11/29/2022]
Abstract
To understand the mechanisms of N3 sleep interruptions in patients with sleepwalking episodes and/or sleep terrors (SW/ST), we evaluated whether autonomic reactions preceded or accompanied behavioural arousals from NREM sleep stage N3. In 20 adult patients with SW/ST and 20 matched controls without parasomnia, heart rate and pulse wave amplitude were measured beat-to-beat during the 10 beats preceding and during the 15 beats succeeding a motor arousal from N3 sleep. Respiratory rate and amplitude were measured during the same 25 successive beats. In patients with SW/ST, the N3 arousals were associated with a 33% increase in heart rate, a 57% decrease in pulse wave amplitude (indicating a major vasoconstriction), a 24% increase in respiratory rate and a doubling of respiratory amplitude. Notably, tachycardia and vasoconstriction started 4 s before motor arousals. A similar profile (tachycardia and vasoconstriction gradually increasing from the 4 s preceding arousal and post-arousal increase of respiratory amplitude, but no polypnea) was also observed, with a lower amplitude, during the less frequent 38 quiet N3 arousals in control subjects. Parasomniac arousals were associated with greater tachycardia, vasoconstriction and polypnea than quiet arousals, with the same pre-arousal gradual increases in heart rate and vasoconstriction. Autonomic arousal occurs 4 s before motor arousal from N3 sleep in patients with SW/ST (with a higher adrenergic reaction than in controls), suggesting that an alarming event during sleep (possibly a worrying sleep mentation or a local subcortical arousal) causes the motor arousal.
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Affiliation(s)
- Nahema Ledard
- Sleep Disorder Unit, Pitié-Salpêtrière University Hospital (APHP), Paris, France.,Sorbonne University, Paris, France
| | - Emilie Artru
- Sleep Disorder Unit, Pitié-Salpêtrière University Hospital (APHP), Paris, France
| | | | - Stefania Redolfi
- Sleep Disorder Unit, Pitié-Salpêtrière University Hospital (APHP), Paris, France.,Sorbonne University, Paris, France
| | - Jean-Louis Golmard
- Sorbonne University, Paris, France.,Department of Biostatistics, Pitié-Salpêtrière University Hospital (APHP), Paris, France
| | | | - Isabelle Arnulf
- Sleep Disorder Unit, Pitié-Salpêtrière University Hospital (APHP), Paris, France.,Sorbonne University, Paris, France
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18
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Baird B, Mota-Rolim SA, Dresler M. The cognitive neuroscience of lucid dreaming. Neurosci Biobehav Rev 2019; 100:305-323. [PMID: 30880167 PMCID: PMC6451677 DOI: 10.1016/j.neubiorev.2019.03.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 03/06/2019] [Accepted: 03/11/2019] [Indexed: 12/17/2022]
Abstract
Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized. Here we review the neuroscientific literature on lucid dreaming, including electroencephalographic, neuroimaging, brain lesion, pharmacological and brain stimulation studies. Electroencephalographic studies of lucid dreaming are mostly underpowered and show mixed results. Neuroimaging data is scant but preliminary results suggest that prefrontal and parietal regions are involved in lucid dreaming. A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams. Finally, we discuss strategies to measure lucid dreaming, including best-practice procedures for the sleep laboratory. Lucid dreaming has clinical and scientific applications, and shows emerging potential as a methodology in the cognitive neuroscience of consciousness. Further research with larger sample sizes and refined methodology is needed.
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Affiliation(s)
- Benjamin Baird
- Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison, Madison, WI, USA.
| | - Sergio A Mota-Rolim
- Brain Institute, Physiology Department and Onofre Lopes University Hospital - Federal University of Rio Grande do Norte, Natal, Brazil
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
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19
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Scarpelli S, Bartolacci C, D'Atri A, Gorgoni M, De Gennaro L. The Functional Role of Dreaming in Emotional Processes. Front Psychol 2019; 10:459. [PMID: 30930809 PMCID: PMC6428732 DOI: 10.3389/fpsyg.2019.00459] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/15/2019] [Indexed: 02/05/2023] Open
Abstract
Dream experience (DE) represents a fascinating condition linked to emotional processes and the human inner world. Although the overlap between REM sleep and dreaming has been overcome, several studies point out that emotional and perceptually vivid contents are more frequent when reported upon awakenings from this sleep stage. Actually, it is well-known that REM sleep plays a pivotal role in the processing of salient and emotional waking-life experiences, strongly contributing to the emotional memory consolidation. In this vein, we highlighted that, to some extent, neuroimaging studies showed that the processes that regulate dreaming and emotional salience in sleep mentation share similar neural substrates of those controlling emotions during wakefulness. Furthermore, the research on EEG correlates of the presence/absence of DE and the results on EEG pattern related to the incorporated memories converged to assign a crucial role of REM theta oscillations in emotional re-processing. In particular, the theta activity is involved in memory processes during REM sleep as well as during the waking state, in line with the continuity hypothesis. Also, the gamma activity seems to be related to emotional processes and dream recall as well as to lucid dreams. Interestingly, similar EEG correlates of DE have been found in clinical samples when nightmares or dreams occur. Research on clinical samples revealed that promoting the rehearsal of frightening contents aimed to change them is a promising method to treat nightmares, and that lucid dreams are associated with an attenuation of nightmares. In this view, DE can defuse emotional traumatic memories when the emotional regulation and the fear extinction mechanisms are compromised by traumatic and frightening events. Finally, dreams could represent a sort of simulation of reality, providing the possibility to create a new scenario with emotional mastery elements to cope with dysphoric items included in nightmares. In addition, it could be hypothesized that the insertion of bizarre items besides traumatic memories might be functional to "impoverish" the negative charge of the experiences.
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Affiliation(s)
| | | | | | | | - Luigi De Gennaro
- Department of Psychology, Sapienza University of Rome, Rome, Italy
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20
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Steinig J, Bazan A, Happe S, Antonetti S, Shevrin H. Processing of a Subliminal Rebus during Sleep: Idiosyncratic Primary versus Secondary Process Associations upon Awakening from REM- versus Non-REM-Sleep. Front Psychol 2017; 8:1955. [PMID: 29209244 PMCID: PMC5701931 DOI: 10.3389/fpsyg.2017.01955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 10/24/2017] [Indexed: 11/24/2022] Open
Abstract
Primary and secondary processes are the foundational axes of the Freudian mental apparatus: one horizontally as a tendency to associate, the primary process, and one vertically as the ability for perspective taking, the secondary process. Primary process mentation is not only supposed to be dominant in the unconscious but also, for example, in dreams. The present study tests the hypothesis that the mental activity during REM-sleep has more characteristics of the primary process, while during non-REM-sleep more secondary process operations take place. Because the solving of a rebus requires the ability to non-contexually condensate the literal reading of single stimuli into a new one, rebus solving is a primary process operation by excellence. In a replication of the dream-rebus study of Shevrin and Fisher (1967), a rebus, which consisted of an image of a comb (German: “Kamm”) and an image of a raft (German: “Floß”), resulting in the German rebus word “kampflos” (Engl.: without a struggle), was flashed subliminally (at 1 ms) to 20 participants before going to sleep. Upon consecutive awakenings participants were asked for a dream report, free associations and an image description. Based on objective association norms, there were significantly more conceptual associations referring to Kamm and Floß indexing secondary process mentation when subjects were awakened from non-REM sleep as compared to REM-awakenings. There were not significantly more rebus associations referring to kampflos indexing primary process mentation when awakened from REM-sleep as compared to non-REM awakenings. However, when the associations were scored on the basis of each subject’s individual norms, there was a rebus effect with more idiosyncratic rebus associations in awakenings after REM than after non-REM-sleep. Our results support the general idea that REM-sleep is characterized by primary process thinking, while non-REM-sleep mentation follows the rules of the secondary process.
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Affiliation(s)
- Jana Steinig
- Department of Psychosomatic Medicine, University of Leipzig, Leipzig, Germany.,Institute of Psychology and Cognition Research, University of Bremen, Bremen, Germany.,Department of Clinical Neurophysiology, Klinikum Bremen-Ost, University of Göttingen, Göttingen, Germany
| | - Ariane Bazan
- Faculté des Sciences Psychologiques et de l'Education, Service de Psychologie Clinique et Différentielle, Université Libre de Bruxelles, Brussels, Belgium
| | - Svenja Happe
- Department of Clinical Neurophysiology, Klinikum Bremen-Ost, University of Göttingen, Göttingen, Germany.,Department of Neurology, Klinik Maria Frieden, Telgte, Germany
| | - Sarah Antonetti
- Faculté des Sciences Psychologiques et de l'Education, Service de Psychologie Clinique et Différentielle, Université Libre de Bruxelles, Brussels, Belgium
| | - Howard Shevrin
- Department of Psychiatry, University of Michigan Medical Center, Ann Arbor, MI, United States
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21
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Mutz J, Javadi AH. Exploring the neural correlates of dream phenomenology and altered states of consciousness during sleep. Neurosci Conscious 2017; 2017:nix009. [PMID: 30042842 PMCID: PMC6007136 DOI: 10.1093/nc/nix009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 03/29/2017] [Accepted: 04/18/2017] [Indexed: 11/13/2022] Open
Abstract
The science of dreaming constitutes a relevant topic in modern-day neuroscientific research and provides major insights into the study of human consciousness. Linking specific, universal, and regularly occurring stages of sleep with dreaming encourages the direct and systematic investigation of a topic that has fascinated humankind for centuries. In this review, we explore to what extent individuals dream during periods of rapid eye movement and non-rapid eye movement sleep, and we introduce research on lucid dreaming. We then discuss how dreaming during different stages of sleep varies in terms of phenomenological characteristics, and to what extent individuals are conscious throughout the sleep cycle. Finally, we provide a synopsis of the previous literature on brain activity during sleep, and we aim to clarify how the neurofunctional changes observed throughout sleep may lead to changes in phenomenological aspects of dreams, and in the domain of consciousness.
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Affiliation(s)
- Julian Mutz
- Department of Epidemiology and Biostatistics, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
| | - Amir-Homayoun Javadi
- School of Psychology, Keynes College, University of Kent, Canterbury, CT2 7NP, UK
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22
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Abstract
Consciousness never fades during wake. However, if awakened from sleep, sometimes we report dreams and sometimes no experiences. Traditionally, dreaming has been identified with REM sleep, characterized by a wake-like, globally ‘activated’, high-frequency EEG. However, dreaming also occurs in NREM sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density EEG, we contrasted the presence and absence of dreaming within NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with a local decrease in low-frequency activity in posterior cortical regions. High-frequency activity within these regions correlated with specific dream contents. Monitoring this posterior ‘hot zone’ predicted whether an individual reported dreaming or the absence of experiences during NREM sleep in real time, suggesting that it may constitute a core correlate of conscious experiences in sleep.
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23
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Daily Life Experiences in Dreams and Sleep-Dependent Memory Consolidation. COGNITIVE NEUROSCIENCE OF MEMORY CONSOLIDATION 2017. [DOI: 10.1007/978-3-319-45066-7_10] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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24
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25
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Cipolli C, Ferrara M, De Gennaro L, Plazzi G. Beyond the neuropsychology of dreaming: Insights into the neural basis of dreaming with new techniques of sleep recording and analysis. Sleep Med Rev 2016; 35:8-20. [PMID: 27569701 DOI: 10.1016/j.smrv.2016.07.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 07/14/2016] [Accepted: 07/14/2016] [Indexed: 02/08/2023]
Abstract
Recent advances in electrophysiological [e.g., surface high-density electroencephalographic (hd-EEG) and intracranial recordings], video-polysomnography (video-PSG), transcranial stimulation and neuroimaging techniques allow more in-depth and more accurate investigation of the neural correlates of dreaming in healthy individuals and in patients with brain-damage, neurodegenerative diseases, sleep disorders or parasomnias. Convergent evidence provided by studies using these techniques in healthy subjects has led to a reformulation of several unresolved issues of dream generation and recall [such as the inter- and intra-individual differences in dream recall and the predictivity of specific EEG rhythms, such as theta in rapid eye movement (REM) sleep, for dream recall] within more comprehensive models of human consciousness and its variations across sleep/wake states than the traditional models, which were largely based on the neurophysiology of REM sleep in animals. These studies are casting new light on the neural bases (in particular, the activity of dorsal medial prefrontal cortex regions and hippocampus and amygdala areas) of the inter- and intra-individual differences in dream recall, the temporal location of specific contents or properties (e.g., lucidity) of dream experience and the processing of memories accessed during sleep and incorporated into dream content. Hd-EEG techniques, used on their own or in combination with neuroimaging, appear able to provide further important insights into how the brain generates not only dreaming during sleep but also some dreamlike experiences in waking.
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Affiliation(s)
- Carlo Cipolli
- Department of Specialty, Diagnostic and Experimental Medicine, University of Bologna, Bologna, Italy
| | - Michele Ferrara
- Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, L'Aquila, Italy
| | - Luigi De Gennaro
- Department of Psychology, Sapienza University of Roma, Roma, Italy
| | - Giuseppe Plazzi
- DIBINEM - Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy; IRCCS - Istituto delle Scienze Neurologiche, AUSL di Bologna, Italy.
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26
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Scarpelli S, D’Atri A, Gorgoni M, Ferrara M, De Gennaro L. EEG oscillations during sleep and dream recall: state- or trait-like individual differences? Front Psychol 2015; 6:605. [PMID: 25999908 PMCID: PMC4423302 DOI: 10.3389/fpsyg.2015.00605] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/23/2015] [Indexed: 02/05/2023] Open
Abstract
Dreaming represents a peculiar form of cognitive activity during sleep. On the basis of the well-known relationship between sleep and memory, there has been a growing interest in the predictive role of human brain activity during sleep on dream recall. Neuroimaging studies indicate that rapid eye movement (REM) sleep is characterized by limbic activation and prefrontal cortex deactivation. This pattern could explain the presence of emotional contents in dream reports. Furthermore, the morphoanatomical measures of amygdala and hippocampus predict some features of dream contents (bizarreness, vividness, and emotional load). More relevant for a general view of dreaming mechanisms, empirical data from neuropsychological and electroencephalographic (EEG) studies support the hypothesis that there is a sort of continuity between the neurophysiological mechanisms of encoding and retrieval of episodic memories across sleep and wakefulness. A notable overlap between the electrophysiological mechanisms underlying emotional memory formation and some peculiar EEG features of REM sleep has been suggested. In particular, theta (5-8 Hz) EEG oscillations on frontal regions in the pre-awakening sleep are predictive of dream recall, which parallels the predictive relation during wakefulness between theta activity and successful retrieval of episodic memory. Although some observations support an interpretation more in terms of an intraindividual than interindividual mechanism, the existing empirical evidence still precludes from definitely disentangling if this relation is explained by state- or trait-like differences.
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Affiliation(s)
- Serena Scarpelli
- Department of Psychology, Sapienza University of Rome, Rome, Italy
| | - Aurora D’Atri
- Department of Psychology, Sapienza University of Rome, Rome, Italy
| | - Maurizio Gorgoni
- Department of Psychology, Sapienza University of Rome, Rome, Italy
| | - Michele Ferrara
- Department of Life, Health and Environmental Sciences, University of L’Aquila, L’Aquila, Italy
| | - Luigi De Gennaro
- Department of Psychology, Sapienza University of Rome, Rome, Italy
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27
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REM sleep and memory reorganization: Potential relevance for psychiatry and psychotherapy. Neurobiol Learn Mem 2015; 122:28-40. [PMID: 25602929 DOI: 10.1016/j.nlm.2015.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 12/28/2014] [Accepted: 01/05/2015] [Indexed: 12/18/2022]
Abstract
Sleep can foster the reorganization of memory, i.e. the emergence of new memory content that has not directly been encoded. Current neurophysiological and behavioral evidence can be integrated into a model positing that REM sleep particularly promotes the disintegration of existing schemas and their recombination in the form of associative thinking, creativity and the shaping of emotional memory. Particularly, REM sleep related dreaming might represent a mentation correlate for the reconfiguration of memory. In a final section, the potential relevance for psychiatry and psychotherapy is discussed.
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28
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Chouchou F, Desseilles M. Heart rate variability: a tool to explore the sleeping brain? Front Neurosci 2014; 8:402. [PMID: 25565936 PMCID: PMC4263095 DOI: 10.3389/fnins.2014.00402] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 11/19/2014] [Indexed: 12/17/2022] Open
Abstract
Sleep is divided into two main sleep stages: (1) non-rapid eye movement sleep (non-REMS), characterized among others by reduced global brain activity; and (2) rapid eye movement sleep (REMS), characterized by global brain activity similar to that of wakefulness. Results of heart rate variability (HRV) analysis, which is widely used to explore autonomic modulation, have revealed higher parasympathetic tone during normal non-REMS and a shift toward sympathetic predominance during normal REMS. Moreover, HRV analysis combined with brain imaging has identified close connectivity between autonomic cardiac modulation and activity in brain areas such as the amygdala and insular cortex during REMS, but no connectivity between brain and cardiac activity during non-REMS. There is also some evidence for an association between HRV and dream intensity and emotionality. Following some technical considerations, this review addresses how brain activity during sleep contributes to changes in autonomic cardiac activity, organized into three parts: (1) the knowledge on autonomic cardiac control, (2) differences in brain and autonomic activity between non-REMS and REMS, and (3) the potential of HRV analysis to explore the sleeping brain, and the implications for psychiatric disorders.
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Affiliation(s)
- Florian Chouchou
- NeuroPain Unit, Lyon Neuroscience Research Centre, CRNL - INSERM U 1028/CNRS UMR 5292, University of Lyon France ; Department of Psychology, University of Namur Namur, Belgium
| | - Martin Desseilles
- Department of Psychology, University of Namur Namur, Belgium ; Cyclotron Research Centre, University of Liège Liège, Belgium
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29
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Abstract
The question that we deal with in this commentary is the need to clarify the synergistic role of different non-rapid eye movement (NREM) sleep stages (stages 2 and 3-4) with REM and while awake in elaborative encoding of episodic memory. If the assumption is that there is isomorphism between neuronal and cognitive networks, then more detailed analysis of NREM sleep and dreams is absolutely necessary.
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30
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Violent somnambulism: A parasomnia of young men with stereotyped dream-like experiences. Med Hypotheses 2014; 83:47-52. [DOI: 10.1016/j.mehy.2014.04.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 03/28/2014] [Accepted: 04/06/2014] [Indexed: 12/30/2022]
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31
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Yoo J, Kwon J, Choe Y. Predictable internal brain dynamics in EEG and its relation to conscious states. Front Neurorobot 2014; 8:18. [PMID: 24917813 PMCID: PMC4043151 DOI: 10.3389/fnbot.2014.00018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Accepted: 05/06/2014] [Indexed: 11/23/2022] Open
Abstract
Consciousness is a complex and multi-faceted phenomenon defying scientific explanation. Part of the reason why this is the case is due to its subjective nature. In our previous computational experiments, to avoid such a subjective trap, we took a strategy to investigate objective necessary conditions of consciousness. Our basic hypothesis was that predictive internal dynamics serves as such a condition. This is in line with theories of consciousness that treat retention (memory), protention (anticipation), and primary impression as the tripartite temporal structure of consciousness. To test our hypothesis, we analyzed publicly available sleep and awake electroencephalogram (EEG) data. Our results show that EEG signals from awake or rapid eye movement (REM) sleep states have more predictable dynamics compared to those from slow-wave sleep (SWS). Since awakeness and REM sleep are associated with conscious states and SWS with unconscious or less consciousness states, these results support our hypothesis. The results suggest an intricate relationship among prediction, consciousness, and time, with potential applications to time perception and neurorobotics.
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Affiliation(s)
- Jaewook Yoo
- Department of Computer Science and Engineering, Texas A&M University College Station, TX, USA
| | - Jaerock Kwon
- Department of Electrical and Computer Engineering, Kettering University Flint, MI, USA
| | - Yoonsuck Choe
- Department of Computer Science and Engineering, Texas A&M University College Station, TX, USA
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32
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Emergence of sensory patterns during sleep highlights differential dynamics of REM and non-REM sleep stages. J Neurosci 2013; 33:14715-28. [PMID: 24027272 DOI: 10.1523/jneurosci.0232-13.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite the profound reduction in conscious awareness associated with sleep, sensory cortex remains highly active during the different sleep stages, exhibiting complex interactions between different cortical sites. The potential functional significance of such spatial patterns and how they change between different sleep stages is presently unknown. In this electrocorticography study of human patients, we examined this question by studying spatial patterns of activity (broadband gamma power) that emerge during sleep (sleep patterns) and comparing them to the functional organization of sensory cortex that is activated by naturalistic stimuli during the awake state. Our results show a high correlation (p < 10(-4), permutation test) between the sleep spatial patterns and the functional organization found during wakefulness. Examining how the sleep patterns changed through the night highlighted a stage-specific difference, whereby the repertoire of such patterns was significantly larger during rapid eye movement (REM) sleep compared with non-REM stages. These results reveal that intricate spatial patterns of sensory functional organization emerge in a stage-specific manner during sleep.
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33
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Wamsley EJ. Dreaming, waking conscious experience, and the resting brain: report of subjective experience as a tool in the cognitive neurosciences. Front Psychol 2013; 4:637. [PMID: 24065940 PMCID: PMC3779833 DOI: 10.3389/fpsyg.2013.00637] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 08/27/2013] [Indexed: 01/03/2023] Open
Abstract
Even when we are ostensibly doing “nothing”—as during states of rest, sleep, and reverie—the brain continues to process information. In resting wakefulness, the mind generates thoughts, plans for the future, and imagines fictitious scenarios. In sleep, when the demands of sensory input are reduced, our experience turns to the thoughts and images we call “dreaming.” Far from being a meaningless distraction, the content of these subjective experiences provides an important and unique source of information about the activities of the resting mind and brain. In both wakefulness and sleep, spontaneous experience combines recent and remote memory fragments into novel scenarios. These conscious experiences may reflect the consolidation of recent memory into long-term storage, an adaptive process that functions to extract general knowledge about the world and adaptively respond to future events. Recent examples from psychology and neuroscience demonstrate that the use of subjective report can provide clues to the function(s) of rest and sleep.
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Affiliation(s)
- Erin J Wamsley
- Department of Psychiatry, Center for Sleep and Cognition, Harvard Medical School and Beth Israel Deaconess Medical Center Boston, MA, USA
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34
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Fox KCR, Nijeboer S, Solomonova E, Domhoff GW, Christoff K. Dreaming as mind wandering: evidence from functional neuroimaging and first-person content reports. Front Hum Neurosci 2013; 7:412. [PMID: 23908622 PMCID: PMC3726865 DOI: 10.3389/fnhum.2013.00412] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 07/11/2013] [Indexed: 11/13/2022] Open
Abstract
Isolated reports have long suggested a similarity in content and thought processes across mind wandering (MW) during waking, and dream mentation during sleep. This overlap has encouraged speculation that both “daydreaming” and dreaming may engage similar brain mechanisms. To explore this possibility, we systematically examined published first-person experiential reports of MW and dreaming and found many similarities: in both states, content is largely audiovisual and emotional, follows loose narratives tinged with fantasy, is strongly related to current concerns, draws on long-term memory, and simulates social interactions. Both states are also characterized by a relative lack of meta-awareness. To relate first-person reports to neural evidence, we compared meta-analytic data from numerous functional neuroimaging (PET, fMRI) studies of the default mode network (DMN, with high chances of MW) and rapid eye movement (REM) sleep (with high chances of dreaming). Our findings show large overlaps in activation patterns of cortical regions: similar to MW/DMN activity, dreaming and REM sleep activate regions implicated in self-referential thought and memory, including medial prefrontal cortex (PFC), medial temporal lobe structures, and posterior cingulate. Conversely, in REM sleep numerous PFC executive regions are deactivated, even beyond levels seen during waking MW. We argue that dreaming can be understood as an “intensified” version of waking MW: though the two share many similarities, dreams tend to be longer, more visual and immersive, and to more strongly recruit numerous key hubs of the DMN. Further, whereas MW recruits fewer PFC regions than goal-directed thought, dreaming appears to be characterized by an even deeper quiescence of PFC regions involved in cognitive control and metacognition, with a corresponding lack of insight and meta-awareness. We suggest, then, that dreaming amplifies the same features that distinguish MW from goal-directed waking thought.
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Affiliation(s)
- Kieran C R Fox
- Department of Psychology, University of British Columbia Vancouver, BC, Canada
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Zadra A, Desautels A, Petit D, Montplaisir J. Somnambulism: clinical aspects and pathophysiological hypotheses. Lancet Neurol 2013; 12:285-94. [PMID: 23415568 DOI: 10.1016/s1474-4422(12)70322-8] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Somnambulism, or sleepwalking, can give rise to a wide range of adverse consequences and is one of the leading causes of sleep-related injury. Accurate diagnosis is crucial for proper management and imperative in an ever-increasing number of medicolegal cases implicating sleep-related violence. Unfortunately, several widely held views of sleepwalking are characterised by key misconceptions, and some established diagnostic criteria are inconsistent with research findings. The traditional idea of somnambulism as a disorder of arousal might be too restrictive and a comprehensive view should include the idea of simultaneous interplay between states of sleep and wakefulness. Abnormal sleep physiology, state dissociation, and genetic factors might explain the pathophysiology of the disorder.
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Affiliation(s)
- Antonio Zadra
- Center for Advanced Research in Sleep Medicine, Hôpital du Sacré-Cœur de Montréal, Montreal, QC, Canada; Department of Psychology, Université de Montréal, Montreal, QC, Canada
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Oudiette D, Dealberto MJ, Uguccioni G, Golmard JL, Merino-Andreu M, Tafti M, Garma L, Schwartz S, Arnulf I. Dreaming without REM sleep. Conscious Cogn 2012; 21:1129-40. [PMID: 22647346 DOI: 10.1016/j.concog.2012.04.010] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 04/01/2012] [Accepted: 04/23/2012] [Indexed: 11/15/2022]
Abstract
To test whether mental activities collected from non-REM sleep are influenced by REM sleep, we suppressed REM sleep using clomipramine 50mg (an antidepressant) or placebo in the evening, in a double blind cross-over design, in 11 healthy young men. Subjects were awakened every hour and asked about their mental activity. The marked (81%, range 39-98%) REM-sleep suppression induced by clomipramine did not substantially affect any aspects of dream recall (report length, complexity, bizarreness, pleasantness and self-perception of dream or thought-like mentation). Since long, complex and bizarre dreams persist even after suppressing REM sleep either partially or totally, it suggests that the generation of mental activity during sleep is independent of sleep stage.
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Affiliation(s)
- Delphine Oudiette
- Sleep Disorders Unit, Pitié-Salpêtrière Hospital, APHP, Paris, France
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Gottesmann C. The involvement of noradrenaline in rapid eye movement sleep mentation. Front Neurol 2011; 2:81. [PMID: 22180750 PMCID: PMC3235734 DOI: 10.3389/fneur.2011.00081] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 11/23/2011] [Indexed: 01/19/2023] Open
Abstract
Noradrenaline, one of the main brain monoamines, has powerful central influences on forebrain neurobiological processes which support the mental activities occurring during the sleep-waking cycle. Noradrenergic neurons are activated during waking, decrease their firing rate during slow wave sleep, and become silent during rapid eye movement (REM) sleep. Although a low level of noradrenaline is still maintained during REM sleep because of diffuse extrasynaptic release without rapid withdrawal, the decrease observed during REM sleep contributes to the mentation disturbances that occur during dreaming, which principally resemble symptoms of schizophrenia but seemingly also of attention deficit hyperactivity disorder.
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Affiliation(s)
- Claude Gottesmann
- Département de Biologie, Université de Nice-Sophia AntipolisNice, France
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Autoscopic phenomena and one’s own body representation in dreams. Conscious Cogn 2011; 20:1009-15. [DOI: 10.1016/j.concog.2011.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2010] [Revised: 12/22/2010] [Accepted: 01/14/2011] [Indexed: 11/21/2022]
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Ruby PM. Experimental research on dreaming: state of the art and neuropsychoanalytic perspectives. Front Psychol 2011; 2:286. [PMID: 22121353 PMCID: PMC3220269 DOI: 10.3389/fpsyg.2011.00286] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 10/10/2011] [Indexed: 11/13/2022] Open
Abstract
Dreaming is still a mystery of human cognition, although it has been studied experimentally for more than a century. Experimental psychology first investigated dream content and frequency. The neuroscientific approach to dreaming arose at the end of the 1950s and soon proposed a physiological substrate of dreaming: rapid eye movement sleep. Fifty years later, this hypothesis was challenged because it could not explain all of the characteristics of dream reports. Therefore, the neurophysiological correlates of dreaming are still unclear, and many questions remain unresolved. Do the representations that constitute the dream emerge randomly from the brain, or do they surface according to certain parameters? Is the organization of the dream's representations chaotic or is it determined by rules? Does dreaming have a meaning? What is/are the function(s) of dreaming? Psychoanalysis provides hypotheses to address these questions. Until now, these hypotheses have received minimal attention in cognitive neuroscience, but the recent development of neuropsychoanalysis brings new hopes of interaction between the two fields. Considering the psychoanalytical perspective in cognitive neuroscience would provide new directions and leads for dream research and would help to achieve a comprehensive understanding of dreaming. Notably, several subjective issues at the core of the psychoanalytic approach, such as the concept of personal meaning, the concept of unconscious episodic memory and the subject's history, are not addressed or considered in cognitive neuroscience. This paper argues that the focus on singularity and personal meaning in psychoanalysis is needed to successfully address these issues in cognitive neuroscience and to progress in the understanding of dreaming and the psyche.
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Affiliation(s)
- Perrine M. Ruby
- INSERM U1028, Lyon Neuroscience Research Center, Brain Dynamics and Cognition TeamLyon, France
- CNRS UMR5292, Lyon Neuroscience Research Center, Brain Dynamics and Cognition TeamLyon, France
- University Lyon 1Lyon, France
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Chellappa SL, Frey S, Knoblauch V, Cajochen C. Cortical activation patterns herald successful dream recall after NREM and REM sleep. Biol Psychol 2011; 87:251-6. [DOI: 10.1016/j.biopsycho.2011.03.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/28/2011] [Accepted: 03/10/2011] [Indexed: 10/18/2022]
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Connectivity pattern changes in default-mode network with deep non-REM and REM sleep. Neurosci Res 2011; 69:322-30. [DOI: 10.1016/j.neures.2010.12.018] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 12/18/2010] [Accepted: 12/22/2010] [Indexed: 11/19/2022]
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William Domhoff G. The neural substrate for dreaming: is it a subsystem of the default network? Conscious Cogn 2011; 20:1163-74. [PMID: 21450492 DOI: 10.1016/j.concog.2011.03.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 02/28/2011] [Accepted: 03/03/2011] [Indexed: 02/02/2023]
Abstract
Building on the content, developmental, and neurological evidence that there are numerous parallels between waking cognition and dreaming, this article argues that the likely neural substrate that supports dreaming, which was discovered through converging lesion and neuroimaging studies, may be a subsystem of the waking default network, which is active during mind wandering, daydreaming, and simulation. Support for this hypothesis would strengthen the case for a more general neurocognitive theory of dreaming that starts with established findings and concepts derived from studies of waking cognition and neurocognition. If this theory is correct, then dreaming may be the quintessential cognitive simulation because it is often highly complex, often includes a vivid sensory environment, unfolds over a duration of a few minutes to a half hour, and is usually experienced as real while it is happening.
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Affiliation(s)
- G William Domhoff
- Department of Psychology, University of California, Santa Cruz, CA 95064, USA.
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Kubota Y, Takasu NN, Horita S, Kondo M, Shimizu M, Okada T, Wakamura T, Toichi M. Dorsolateral prefrontal cortical oxygenation during REM sleep in humans. Brain Res 2011; 1389:83-92. [PMID: 21382356 DOI: 10.1016/j.brainres.2011.02.061] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 02/17/2011] [Accepted: 02/19/2011] [Indexed: 12/18/2022]
Abstract
Previous neuroimaging studies that examined cerebral blood flow during rapid eye movement (REM) sleep have reported inconsistent findings regarding the activity of the dorsolateral prefrontal cortex (DLPFC). Although most previous positron emission tomography (PET) studies failed to detect DLPFC activation during REM sleep, several studies have observed DLPFC activation, possibly reflecting transient prefrontal activities related to REM. More recently, an event-related functional magnetic resonance imaging (fMRI) study observed REM-locked activation of the DLPFC during REM sleep. The present study investigated hemodynamic changes of the DLPFC throughout the REM sleep period in 25 subjects using near-infrared spectroscopy. Continuous monitoring of changes in the hemoglobin (Hb) concentration and tissue oxygenation index (TOI, proportion of oxygenated-Hb to total-Hb) in the bilateral DLPFC was conducted every 0.5s, simultaneously with polysomnographic recordings. Eight of the 25 subjects showed REM sleep, and all indicated a clear increase in both the oxygenated-Hb concentration and TOI from baseline at the occurrence of first REM, relative to prior stage 2 sleep. The results indicate that the appearance of the first REM that occurred just after onset of the REM sleep closely coincides with the activation of the DLPFC, which could play a role in cognitive activities during REM sleep in humans.
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Affiliation(s)
- Yasutaka Kubota
- Health and Medical Services Center, Shiga University, Shiga, Japan.
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Abstract
It is now well established that post-learning sleep is beneficial for human memory performance. At the same time, it has long been known that learning experiences influence the content of subsequent sleep mentation (i.e., "dreaming"). Here, we review evidence that newly encoded memories are reactivated and consolidated in the sleeping brain, and that this process is directly reflected in the content of concomitant sleep mentation, providing a valuable window into the mnemonic functions of sleep.
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Affiliation(s)
- Erin J Wamsley
- Instructor in Psychiatry, Harvard Medical School/Beth Israel Deaconess Medical Center. Boston MA
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Transient changes in frontal alpha asymmetry as a measure of emotional and physical distress during sleep. Brain Res 2011; 1367:234-49. [DOI: 10.1016/j.brainres.2010.09.090] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Revised: 09/24/2010] [Accepted: 09/25/2010] [Indexed: 11/22/2022]
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Desseilles M, Dang-Vu TT, Sterpenich V, Schwartz S. Cognitive and emotional processes during dreaming: a neuroimaging view. Conscious Cogn 2010; 20:998-1008. [PMID: 21075010 DOI: 10.1016/j.concog.2010.10.005] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 09/03/2010] [Accepted: 10/06/2010] [Indexed: 12/16/2022]
Abstract
Dream is a state of consciousness characterized by internally-generated sensory, cognitive and emotional experiences occurring during sleep. Dream reports tend to be particularly abundant, with complex, emotional, and perceptually vivid experiences after awakenings from rapid eye movement (REM) sleep. This is why our current knowledge of the cerebral correlates of dreaming, mainly derives from studies of REM sleep. Neuroimaging results show that REM sleep is characterized by a specific pattern of regional brain activity. We demonstrate that this heterogeneous distribution of brain activity during sleep explains many typical features in dreams. Reciprocally, specific dream characteristics suggest the activation of selective brain regions during sleep. Such an integration of neuroimaging data of human sleep, mental imagery, and the content of dreams is critical for current models of dreaming; it also provides neurobiological support for an implication of sleep and dreaming in some important functions such as emotional regulation.
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Kahan TL, LaBerge SP. Dreaming and waking: similarities and differences revisited. Conscious Cogn 2010; 20:494-514. [PMID: 20933437 DOI: 10.1016/j.concog.2010.09.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 09/03/2010] [Accepted: 09/04/2010] [Indexed: 11/24/2022]
Abstract
Dreaming is often characterized as lacking high-order cognitive (HOC) skills. In two studies, we test the alternative hypothesis that the dreaming mind is highly similar to the waking mind. Multiple experience samples were obtained from late-night REM sleep and waking, following a systematic protocol described in Kahan (2001). Results indicated that reported dreaming and waking experiences are surprisingly similar in their cognitive and sensory qualities. Concurrently, ratings of dreaming and waking experiences were markedly different on questions of general reality orientation and logical organization (e.g., the bizarreness or typicality of the events, actions, and locations). Consistent with other recent studies (e.g., Bulkeley & Kahan, 2008; Kozmová & Wolman, 2006), experiences sampled from dreaming and waking were more similar with respect to their process features than with respect to their structural features.
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Affiliation(s)
- Tracey L Kahan
- Department of Psychology, Santa Clara University, Santa Clara, CA 95053, United States.
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Abstract
Understanding dreams has long been considered fundamental to the development of a theory of consciousness. Evidence from neurobiology and neuroimaging research has paved the way for new theories of dreaming that are empirically supported. In this article we argue that dreaming is a unique state of consciousness that incorporates 3 temporal dimensions: experience of the present, processing of the past, and preparation for the future. The temporal complexity of dreams is made possible in part by the unique neurobiological environment of sleep, in which stimuli are internally generated and many of the restrictions associated with waking thought are absent. Because dream consciousness is not determined by sensory stimuli, a flexible integration of past experiences and the forging of novel connections are possible. We argue that disparate dream theories may not be mutually exclusive but rather relate to different temporal domains of the dream state.
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Oudiette D, Leu S, Pottier M, Buzare MA, Brion A, Arnulf I. Dreamlike mentations during sleepwalking and sleep terrors in adults. Sleep 2010; 32:1621-7. [PMID: 20041598 DOI: 10.1093/sleep/32.12.1621] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Sleep terrors and sleepwalking are described as arousals from slow wave sleep with no or poor mental recollection. OBJECTIVE To characterize the mental content retrospectively associated with sleep terrors or sleepwalking. SETTING University Hospital. DESIGN Controlled prospective cohort. PARTICIPANTS Forty-three patients referred for severe sleepwalking/sleep terrors (age: 26 +/- 7 y, 46% men, 5 with sleep terrors only, 8 with sleepwalking only, and 30 with both), matched with 25 healthy control subjects. INTERVENTION Thirty-eight of the 43 patients (88%) underwent an interview about the frequency, time, behaviors, and mental content associated with the episodes of sleepwalking and sleep terrors, whenever they occurred over a lifetime. The mental contents were classified for complexity (Orlinski score), and for characters, emotions, fortune/misfortune, and social interactions (Hall and Van de Castle categories). Patients and control subjects underwent an overnight video-polysomnogram. RESULTS Seventy-one percent of the patients reported at least 1 dreamlike mentation associated with the sleepwalking/sleep terrors episode. The dreamlike mentation action corresponded with the observed behavior. A total of 106 dreamlike mentations were collected (mean: 3 +/- 3.4 dreamlike mentations/patient, range 0-17). Most (95%) dreamlike mentations consisted of a single visual scene. These dreamlike mentations were frequently unpleasant, with aggression in 24% (the dreamer being always the victim), misfortune in 54%, and apprehension in 84%. The patients with dream mentations reported more severe daytime sleepiness. CONCLUSION Short, unpleasant dreamlike mentations may occur during sleepwalking/sleep terrors episodes, suggesting that a complex mental activity takes place during slow wave sleep. Sleepwalking may thus represent acting out of the corresponding dreamlike mentation.
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Affiliation(s)
- Delphine Oudiette
- Sleep Disorders Unit, Pitié-Salpêtriere Hospital, APHP UMR 975, CRICM, and Paris 6 University, Paris, France
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Nir Y, Tononi G. Dreaming and the brain: from phenomenology to neurophysiology. Trends Cogn Sci 2010; 14:88-100. [PMID: 20079677 DOI: 10.1016/j.tics.2009.12.001] [Citation(s) in RCA: 249] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/05/2009] [Accepted: 12/08/2009] [Indexed: 01/22/2023]
Abstract
Dreams are a remarkable experiment in psychology and neuroscience, conducted every night in every sleeping person. They show that the human brain, disconnected from the environment, can generate an entire world of conscious experiences by itself. Content analysis and developmental studies have promoted understanding of dream phenomenology. In parallel, brain lesion studies, functional imaging and neurophysiology have advanced current knowledge of the neural basis of dreaming. It is now possible to start integrating these two strands of research to address fundamental questions that dreams pose for cognitive neuroscience: how conscious experiences in sleep relate to underlying brain activity; why the dreamer is largely disconnected from the environment; and whether dreaming is more closely related to mental imagery or to perception.
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Affiliation(s)
- Yuval Nir
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA
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