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Pérez P, Manasova D, Hermann B, Raimondo F, Rohaut B, Bekinschtein TA, Naccache L, Arzi A, Sitt JD. Content-state dimensions characterize different types of neuronal markers of consciousness. Neurosci Conscious 2024; 2024:niae027. [PMID: 39011546 PMCID: PMC11246840 DOI: 10.1093/nc/niae027] [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: 11/08/2023] [Revised: 05/30/2024] [Accepted: 06/08/2024] [Indexed: 07/17/2024] Open
Abstract
Identifying the neuronal markers of consciousness is key to supporting the different scientific theories of consciousness. Neuronal markers of consciousness can be defined to reflect either the brain signatures underlying specific conscious content or those supporting different states of consciousness, two aspects traditionally studied separately. In this paper, we introduce a framework to characterize markers according to their dynamics in both the "state" and "content" dimensions. The 2D space is defined by the marker's capacity to distinguish the conscious states from non-conscious states (on the x-axis) and the content (e.g. perceived versus unperceived or different levels of cognitive processing on the y-axis). According to the sign of the x- and y-axis, markers are separated into four quadrants in terms of how they distinguish the state and content dimensions. We implement the framework using three types of electroencephalography markers: markers of connectivity, markers of complexity, and spectral summaries. The neuronal markers of state are represented by the level of consciousness in (i) healthy participants during a nap and (ii) patients with disorders of consciousness. On the other hand, the neuronal markers of content are represented by (i) the conscious content in healthy participants' perception task using a visual awareness paradigm and (ii) conscious processing of hierarchical regularities using an auditory local-global paradigm. In both cases, we see separate clusters of markers with correlated and anticorrelated dynamics, shedding light on the complex relationship between the state and content of consciousness and emphasizing the importance of considering them simultaneously. This work presents an innovative framework for studying consciousness by examining neuronal markers in a 2D space, providing a valuable resource for future research, with potential applications using diverse experimental paradigms, neural recording techniques, and modeling investigations.
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Affiliation(s)
- Pauline Pérez
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Hospice Civils de Lyon—HCL, Département anesthésie-réanimation, Hôpital Edouard Herriot
- Neuro ICU, DMU Neurosciences, AP-HP, Hôpital de la Pitié Salpêtrière, Paris 75013, France
| | - Dragana Manasova
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Université Paris Cité, Paris 75006, France
| | - Bertrand Hermann
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Université Paris Cité, Paris 75006, France
- Medical Intensive Care Unit, HEGP Hôpital, Assistance Publique—Hôpitaux de Paris-Centre (APHP-Centre), Paris 75015, France
| | - Federico Raimondo
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Institute of Neuroscience and Medicine (INM-7: Brain and Behaviour), Research Centre Jülich, Jülich 52428, Germany
- Institute of Systems Neuroscience, Heinrich Heine University Düsseldorf, Dusseldorf 40225, Germany
| | - Benjamin Rohaut
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Neuro ICU, DMU Neurosciences, AP-HP, Hôpital de la Pitié Salpêtrière, Paris 75013, France
| | - Tristán A Bekinschtein
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - Lionel Naccache
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- AP-HP, Hôpital Pitié-Salpêtrière, Service de Neurophysiologie Clinique, Paris 75013, France
| | - Anat Arzi
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada and Department of Cognitive and Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jacobo D Sitt
- Institut du Cerveau - Paris Brain Institute, Inserm, CNRS, Sorbonne Université, Paris 75013, France
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Mudrik L, Hirschhorn R, Korisky U. Taking consciousness for real: Increasing the ecological validity of the study of conscious vs. unconscious processes. Neuron 2024; 112:1642-1656. [PMID: 38653247 PMCID: PMC11100345 DOI: 10.1016/j.neuron.2024.03.031] [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: 02/15/2024] [Revised: 03/23/2024] [Accepted: 03/29/2024] [Indexed: 04/25/2024]
Abstract
The study of consciousness has developed well-controlled, rigorous methods for manipulating and measuring consciousness. Yet, in the process, experimental paradigms grew farther away from everyday conscious and unconscious processes, which raises the concern of ecological validity. In this review, we suggest that the field can benefit from adopting a more ecological approach, akin to other fields of cognitive science. There, this approach challenged some existing hypotheses, yielded stronger effects, and enabled new research questions. We argue that such a move is critical for studying consciousness, where experimental paradigms tend to be artificial and small effect sizes are relatively prevalent. We identify three paths for doing so-changing the stimuli and experimental settings, changing the measures, and changing the research questions themselves-and review works that have already started implementing such approaches. While acknowledging the inherent challenges, we call for increasing ecological validity in consciousness studies.
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Affiliation(s)
- Liad Mudrik
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel; Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel.
| | - Rony Hirschhorn
- Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Uri Korisky
- School of Psychological Sciences, Tel Aviv University, Tel Aviv, Israel
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3
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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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Schmidig FJ, Ruch S, Henke K. Episodic long-term memory formation during slow-wave sleep. eLife 2024; 12:RP89601. [PMID: 38661727 PMCID: PMC11045222 DOI: 10.7554/elife.89601] [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] [Indexed: 04/26/2024] Open
Abstract
We are unresponsive during slow-wave sleep but continue monitoring external events for survival. Our brain wakens us when danger is imminent. If events are non-threatening, our brain might store them for later consideration to improve decision-making. To test this hypothesis, we examined whether novel vocabulary consisting of simultaneously played pseudowords and translation words are encoded/stored during sleep, and which neural-electrical events facilitate encoding/storage. An algorithm for brain-state-dependent stimulation selectively targeted word pairs to slow-wave peaks or troughs. Retrieval tests were given 12 and 36 hr later. These tests required decisions regarding the semantic category of previously sleep-played pseudowords. The sleep-played vocabulary influenced awake decision-making 36 hr later, if targeted to troughs. The words' linguistic processing raised neural complexity. The words' semantic-associative encoding was supported by increased theta power during the ensuing peak. Fast-spindle power ramped up during a second peak likely aiding consolidation. Hence, new vocabulary played during slow-wave sleep was stored and influenced decision-making days later.
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Affiliation(s)
| | - Simon Ruch
- Institute of Psychology, University of BernBernSwitzerland
- Faculty of Psychology, UniDistance SuisseBrigSwitzerland
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Paller KA. Recurring memory reactivation: The offline component of learning. Neuropsychologia 2024; 196:108840. [PMID: 38417546 PMCID: PMC10981210 DOI: 10.1016/j.neuropsychologia.2024.108840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 02/19/2024] [Accepted: 02/25/2024] [Indexed: 03/01/2024]
Abstract
One can be aware of the effort needed to memorize a new fact or to recall the name of a new acquaintance. Because of experiences like this, learning can seem to have only two components, encoding information and, after some delay, retrieving information. To the contrary, learning entails additional, intervening steps that sometimes are hidden from the learner. For firmly acquiring fact and event knowledge in particular, learners are generally not cognizant of the necessity of offline consolidation. The memories that persist to be available reliably at a later time, according to the present conceptualization, are the ones we repeatedly rehearse and integrate with other knowledge, whether we do this intentionally or unknowingly, awake or asleep. This article examines the notion that learning is not a function of waking brain activity alone. What happens in the brain while we sleep also impacts memory storage, and consequently is a critical component of learning. The idea that memories can change over time and become enduring has long been present in memory research and is foundational for the concept of memory consolidation. Nevertheless, the notion that memory consolidation happens during sleep faced much resistance before eventually being firmly established. Research is still needed to elucidate the operation and repercussions of repeated reactivation during sleep. Comprehensively understanding how offline memory reactivation contributes to learning is vital for both theoretical and practical considerations.
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Affiliation(s)
- Ken A Paller
- Northwestern University, Department of Psychology, Evanston, IL, 60208, USA.
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Salvesen L, Capriglia E, Dresler M, Bernardi G. Influencing dreams through sensory stimulation: A systematic review. Sleep Med Rev 2024; 74:101908. [PMID: 38417380 PMCID: PMC11009489 DOI: 10.1016/j.smrv.2024.101908] [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: 10/06/2023] [Revised: 01/29/2024] [Accepted: 02/12/2024] [Indexed: 03/01/2024]
Abstract
Sleep is typically considered a state of disconnection from the environment, yet instances of external sensory stimuli influencing dreams have been reported for centuries. Explaining this phenomenon could provide valuable insight into dreams' generative and functional mechanisms, the factors that promote sleep continuity, and the processes that underlie conscious awareness. Moreover, harnessing sensory stimuli for dream engineering could benefit individuals suffering from dream-related alterations. This PRISMA-compliant systematic review assessed the current evidence concerning the influence of sensory stimulation on sleep mentation. We included 51 publications, of which 21 focused on auditory stimulation, ten on somatosensory stimulation, eight on olfactory stimulation, four on visual stimulation, two on vestibular stimulation, and one on multimodal stimulation. Furthermore, nine references explored conditioned associative stimulation: six focused on targeted memory reactivation protocols and three on targeted lucid reactivation protocols. The reported frequency of stimulus-dependent dream changes across studies ranged from 0 to ∼80%, likely reflecting a considerable heterogeneity of definitions and methodological approaches. Our findings highlight a lack of comprehensive understanding of the mechanisms, functions, and neurophysiological correlates of stimulus-dependent dream changes. We suggest that a paradigm shift is required for meaningful progress in this field.
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Affiliation(s)
- Leila Salvesen
- Sleep, Plasticity, and Conscious Experience Group, MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Lucca, Italy; Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Elena Capriglia
- Sleep, Plasticity, and Conscious Experience Group, MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Lucca, Italy; Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Giulio Bernardi
- Sleep, Plasticity, and Conscious Experience Group, MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Lucca, Italy.
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Andrillon T, Taillard J, Strauss M. Sleepiness and the transition from wakefulness to sleep. Neurophysiol Clin 2024; 54:102954. [PMID: 38460284 DOI: 10.1016/j.neucli.2024.102954] [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: 12/10/2023] [Revised: 02/02/2024] [Accepted: 02/03/2024] [Indexed: 03/11/2024] Open
Abstract
The transition from wakefulness to sleep is a progressive process that is reflected in the gradual loss of responsiveness, an alteration of cognitive functions, and a drastic shift in brain dynamics. These changes do not occur all at once. The sleep onset period (SOP) refers here to this period of transition between wakefulness and sleep. For example, although transitions of brain activity at sleep onset can occur within seconds in a given brain region, these changes occur at different time points across the brain, resulting in a SOP that can last several minutes. Likewise, the transition to sleep impacts cognitive and behavioral levels in a graded and staged fashion. It is often accompanied and preceded by a sensation of drowsiness and the subjective feeling of a need for sleep, also associated with specific physiological and behavioral signatures. To better characterize fluctuations in vigilance and the SOP, a multidimensional approach is thus warranted. Such a multidimensional approach could mitigate important limitations in the current classification of sleep, leading ultimately to better diagnoses and treatments of individuals with sleep and/or vigilance disorders. These insights could also be translated in real-life settings to either facilitate sleep onset in individuals with sleep difficulties or, on the contrary, prevent or control inappropriate sleep onsets.
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Affiliation(s)
- Thomas Andrillon
- Paris Brain Institute, Sorbonne Université, Inserm-CNRS, Paris 75013, France; Monash Centre for Consciousness & Contemplative Studies, Monash University, Melbourne, VIC 3800, Australia
| | - Jacques Taillard
- Univ. Bordeaux, CNRS, SANPSY, UMR 6033, F-33000 Bordeaux, France
| | - Mélanie Strauss
- Université libre de Bruxelles (ULB), Hôpital Universitaire de Bruxelles (H.U.B), CUB Hôpital Érasme, Services de Neurologie, Psychiatrie et Laboratoire du sommeil, Route de Lennik 808 1070 Bruxelles, Belgium; Neuropsychology and Functional Neuroimaging Research Group (UR2NF), Center for Research in Cognition and Neurosciences (CRCN), Université Libre de Bruxelles, B-1050 Brussels, Belgium.
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Cecconi B, Montupil J, Mortaheb S, Panda R, Sanders RD, Phillips C, Alnagger N, Remacle E, Defresne A, Boly M, Bahri MA, Lamalle L, Laureys S, Gosseries O, Bonhomme V, Annen J. Study protocol: Cerebral characterization of sensory gating in disconnected dreaming states during propofol anesthesia using fMRI. Front Neurosci 2024; 18:1306344. [PMID: 38419667 PMCID: PMC10900985 DOI: 10.3389/fnins.2024.1306344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
Background Disconnected consciousness describes a state in which subjective experience (i.e., consciousness) becomes isolated from the external world. It appears frequently during sleep or sedation, when subjective experiences remain vivid but are unaffected by external stimuli. Traditional methods of differentiating connected and disconnected consciousness, such as relying on behavioral responsiveness or on post-anesthesia reports, have demonstrated limited accuracy: unresponsiveness has been shown to not necessarily equate to unconsciousness and amnesic effects of anesthesia and sleep can impair explicit recollection of events occurred during sleep/sedation. Due to these methodological challenges, our understanding of the neural mechanisms underlying sensory disconnection remains limited. Methods To overcome these methodological challenges, we employ a distinctive strategy by combining a serial awakening paradigm with auditory stimulation during mild propofol sedation. While under sedation, participants are systematically exposed to auditory stimuli and questioned about their subjective experience (to assess consciousness) and their awareness of the sounds (to evaluate connectedness/disconnectedness from the environment). The data collected through interviews are used to categorize participants into connected and disconnected consciousness states. This method circumvents the requirement for responsiveness in assessing consciousness and mitigates amnesic effects of anesthesia as participants are questioned while still under sedation. Functional MRI data are concurrently collected to investigate cerebral activity patterns during connected and disconnected states, to elucidate sensory disconnection neural gating mechanisms. We examine whether this gating mechanism resides at the thalamic level or results from disruptions in information propagation to higher cortices. Furthermore, we explore the potential role of slow-wave activity (SWA) in inducing disconnected consciousness by quantifying high-frequency BOLD oscillations, a known correlate of slow-wave activity. Discussion This study represents a notable advancement in the investigation of sensory disconnection. The serial awakening paradigm effectively mitigates amnesic effects by collecting reports immediately after regaining responsiveness, while still under sedation. Ultimately, this research holds the potential to understand how sensory gating is achieved at the neural level. These biomarkers might be relevant for the development of sensitive anesthesia monitoring to avoid intraoperative connected consciousness and for the assessment of patients suffering from pathologically reduced consciousness. Clinical trial registration European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), identifier 2020-003524-17.
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Affiliation(s)
- Benedetta Cecconi
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Javier Montupil
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Centre Hospitalier Régional de la Citadelle (CHR Citadelle), Liège, Belgium
| | - Sepehr Mortaheb
- Physiology of Cognition Research Lab, GIGA-Consciousness, GIGA Institute, University of Liège, Liege, Belgium
| | - Rajanikant Panda
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Robert D. Sanders
- Central Clinical School, Sydney Medical School & NHMRC Clinical Trials Centre, University of Sydney, Camperdown, NSW, Australia
- Department of Anaesthetics & Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Christophe Phillips
- GIGA-CRC—In vivo Imaging—Neuroimaging, Data Acquisition and Processing, GIGA Institute, University of Liège, Liège, Belgium
| | - Naji Alnagger
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Emma Remacle
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
| | - Aline Defresne
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Centre Hospitalier Régional de la Citadelle (CHR Citadelle), Liège, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liège University Hospital, Liège, Belgium
| | - Melanie Boly
- Department of Psychiatry, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin, Madison, WI, United States
| | - Mohamed Ali Bahri
- GIGA-CRC—In vivo Imaging—Aging & Memory, GIGA Institute, University of Liège, Liège, Belgium
| | - Laurent Lamalle
- GIGA-CRC—In vivo Imaging—Aging & Memory, GIGA Institute, University of Liège, Liège, Belgium
| | - Steven Laureys
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
- Cervo Brain Research Centre, University Institute in Mental Health of Quebec, Québec, QC, Canada
- Consciousness Science Institute, Hangzhou Normal University, Hangzhou, China
| | - Olivia Gosseries
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Vincent Bonhomme
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liège University Hospital, Liège, Belgium
| | - Jitka Annen
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
- Department of Data Analysis, University of Ghent, Ghent, Belgium
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Tauber JM, Brincat SL, Stephen EP, Donoghue JA, Kozachkov L, Brown EN, Miller EK. Propofol-mediated Unconsciousness Disrupts Progression of Sensory Signals through the Cortical Hierarchy. J Cogn Neurosci 2024; 36:394-413. [PMID: 37902596 PMCID: PMC11161138 DOI: 10.1162/jocn_a_02081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
A critical component of anesthesia is the loss of sensory perception. Propofol is the most widely used drug for general anesthesia, but the neural mechanisms of how and when it disrupts sensory processing are not fully understood. We analyzed local field potential and spiking recorded from Utah arrays in auditory cortex, associative cortex, and cognitive cortex of nonhuman primates before and during propofol-mediated unconsciousness. Sensory stimuli elicited robust and decodable stimulus responses and triggered periods of stimulus-related synchronization between brain areas in the local field potential of Awake animals. By contrast, propofol-mediated unconsciousness eliminated stimulus-related synchrony and drastically weakened stimulus responses and information in all brain areas except for auditory cortex, where responses and information persisted. However, we found stimuli occurring during spiking Up states triggered weaker spiking responses than in Awake animals in auditory cortex, and little or no spiking responses in higher order areas. These results suggest that propofol's effect on sensory processing is not just because of asynchronous Down states. Rather, both Down states and Up states reflect disrupted dynamics.
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Affiliation(s)
- John M Tauber
- Massachusetts Institute of Technology, Cambridge, MA
| | | | | | | | - Leo Kozachkov
- Massachusetts Institute of Technology, Cambridge, MA
| | - Emery N Brown
- Massachusetts Institute of Technology, Cambridge, MA
- Massachusetts General Hospital, Boston
- Harvard University, Cambridge, MA
| | - Earl K Miller
- Massachusetts Institute of Technology, Cambridge, MA
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10
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Coenen A. Sensory gating and gaining in sleep: the balance between the protection of sleep and the safeness of life (a review). J Sleep Res 2024:e14152. [PMID: 38286435 DOI: 10.1111/jsr.14152] [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: 04/02/2023] [Revised: 11/28/2023] [Accepted: 01/10/2024] [Indexed: 01/31/2024]
Abstract
Sleep is a brain state characterised by a low vigilance level and diminished consciousness. Reaction to and processing of external stimuli is attenuated in sleep. During sleep, the reticular thalamic nucleus reduces the flow of sensory activity to the cerebral cortex through inhibition of the thalamus. This sensory gating process facilitates sleep. After reaching the afferent layers of primary cortex, the reduced sensory flow is adjusted, gained, and processed within various cortical layers before being transferred by the corticofugal system back to appropriate subdivisions of the thalamus as feedback. Thalamic subdivisions then dispatch this sensory information to related areas of the cerebral cortex, where it is (sub)consciously perceived. When necessary, a sleeping individual can be awakened by a wake-up call, either by stimuli indicating danger, or by personally meaningful stimuli. It is safe for a sleeping individual that it can be aroused when necessary. Evidently, there are two processes by which the brain adjusts the response to sensory stimuli before entering (sub)consciousness. Firstly 'sensory gating', a process favourable to the maintenance of sleep by reducing the sensory input to the brain through the reticular thalamic nucleus and secondly 'sensory gaining', a process implying that the gained preserved sensory input is continuously analysed by the corticofugal system to detect dangerous and relevant environmental elements, indispensable for safeness and well-being of the sleeper.
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Affiliation(s)
- Anton Coenen
- Department of Biological Psychology, Donders Centre for Cognition, Radboud University, Nijmegen, The Netherlands
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11
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Sandoval Ortega RA, Renard M, Cohen MX, Nevian T. Interactive effects of pain and arousal state on heart rate and cortical activity in the mouse anterior cingulate and somatosensory cortices. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2024; 15:100157. [PMID: 38764613 PMCID: PMC11099324 DOI: 10.1016/j.ynpai.2024.100157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 05/21/2024]
Abstract
Sensory disconnection is a hallmark of sleep, yet the cortex retains some ability to process sensory information. Acute noxious stimulation during sleep increases the heart rate and the likelihood of awakening, indicating that certain mechanisms for pain sensing and processing remain active. However, processing of somatosensory information, including pain, during sleep remains underexplored. To assess somatosensation in natural sleep, we simultaneously recorded heart rate and local field potentials in the anterior cingulate (ACC) and somatosensory (S1) cortices of naïve, adult male mice, while applying noxious and non-noxious stimuli to their hind paws throughout their sleep-wake cycle. Noxious stimuli evoked stronger heart rate increases in both wake and non-rapid eye movement sleep (NREMS), and resulted in larger awakening probability in NREMS, as compared to non-noxious stimulation, suggesting differential processing of noxious and non-noxious information during sleep. Somatosensory information differentially reached S1 and ACC in sleep, eliciting complex transient and sustained responses in the delta, alpha, and gamma frequency bands as well as somatosensory evoked potentials. These dynamics depended on sleep state, the behavioral response to the stimulation and stimulation intensity (non-noxious vs. noxious). Furthermore, we found a correlation of the heart rate with the gamma band in S1 in the absence of a reaction in wake and sleep for noxious stimulation. These findings confirm that somatosensory information, including nociception, is sensed and processed during sleep even in the absence of a behavioral response.
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Affiliation(s)
| | - Margot Renard
- Neuronal Plasticity Group, Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
| | - Michael X. Cohen
- Synchronization in Neural Systems Lab, Donders Centre for Medical Neuroscience, Radboud University Medical Center, Houtlaan 4, 6525 XZ Nijmegen, the Netherlands
| | - Thomas Nevian
- Neuronal Plasticity Group, Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
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12
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Koculak M, Wierzchoń M. Modelling human vision needs to account for subjective experience. Behav Brain Sci 2023; 46:e397. [PMID: 38054283 DOI: 10.1017/s0140525x2300170x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023]
Abstract
Vision is inseparably connected to perceptual awareness which can be seen as the culmination of sensory processing. Studies on conscious vision reveal that object recognition is just one of the means through which our representation of the world is built. We propose an operationalization of subjective experience in the context of deep neural networks (DNNs) that could encourage a more thorough comparison of human and artificial vision.
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Affiliation(s)
- Marcin Koculak
- Centre for Brain Research, Jagiellonian University, Krakow, Poland
- Consciousness Lab, Institute of Psychology, Jagiellonian University, Krakow, Poland ://c-lab.pl
| | - Michał Wierzchoń
- Centre for Brain Research, Jagiellonian University, Krakow, Poland
- Consciousness Lab, Institute of Psychology, Jagiellonian University, Krakow, Poland ://c-lab.pl
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13
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Andrillon T, Oudiette D. What is sleep exactly? Global and local modulations of sleep oscillations all around the clock. Neurosci Biobehav Rev 2023; 155:105465. [PMID: 37972882 DOI: 10.1016/j.neubiorev.2023.105465] [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: 01/17/2023] [Revised: 09/29/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023]
Abstract
Wakefulness, non-rapid eye-movement (NREM) and rapid eye-movement (REM) sleep differ from each other along three dimensions: behavioral, phenomenological, physiological. Although these dimensions often fluctuate in step, they can also dissociate. The current paradigm that views sleep as made of global NREM and REM states fail to account for these dissociations. This conundrum can be dissolved by stressing the existence and significance of the local regulation of sleep. We will review the evidence in animals and humans, healthy and pathological brains, showing different forms of local sleep and the consequences on behavior, cognition, and subjective experience. Altogether, we argue that the notion of local sleep provides a unified account for a host of phenomena: dreaming in REM and NREM sleep, NREM and REM parasomnias, intrasleep responsiveness, inattention and mind wandering in wakefulness. Yet, the physiological origins of local sleep or its putative functions remain unclear. Exploring further local sleep could provide a unique and novel perspective on how and why we sleep.
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Affiliation(s)
- Thomas Andrillon
- Paris Brain Institute, Sorbonne Université, Inserm-CNRS, Paris 75013, France; Monash Centre for Consciousness & Contemplative Studies, Monash University, Melbourne, VIC 3800, Australia.
| | - Delphine Oudiette
- Paris Brain Institute, Sorbonne Université, Inserm-CNRS, Paris 75013, France
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14
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Klar P, Çatal Y, Fogel S, Jocham G, Langner R, Owen AM, Northoff G. Auditory inputs modulate intrinsic neuronal timescales during sleep. Commun Biol 2023; 6:1180. [PMID: 37985812 PMCID: PMC10661171 DOI: 10.1038/s42003-023-05566-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 11/09/2023] [Indexed: 11/22/2023] Open
Abstract
Functional magnetic resonance imaging (fMRI) studies have demonstrated that intrinsic neuronal timescales (INT) undergo modulation by external stimulation during consciousness. It remains unclear if INT keep the ability for significant stimulus-induced modulation during primary unconscious states, such as sleep. This fMRI analysis addresses this question via a dataset that comprises an awake resting-state plus rest and stimulus states during sleep. We analyzed INT measured via temporal autocorrelation supported by median frequency (MF) in the frequency-domain. Our results were replicated using a biophysical model. There were two main findings: (1) INT prolonged while MF decreased from the awake resting-state to the N2 resting-state, and (2) INT shortened while MF increased during the auditory stimulus in sleep. The biophysical model supported these results by demonstrating prolonged INT in slowed neuronal populations that simulate the sleep resting-state compared to an awake state. Conversely, under sine wave input simulating the stimulus state during sleep, the model's regions yielded shortened INT that returned to the awake resting-state level. Our results highlight that INT preserve reactivity to stimuli in states of unconsciousness like sleep, enhancing our understanding of unconscious brain dynamics and their reactivity to stimuli.
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Affiliation(s)
- Philipp Klar
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany.
- Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany.
| | - Yasir Çatal
- The Royal's Institute of Mental Health Research & University of Ottawa, Brain and Mind Research Institute, Centre for Neural Dynamics, Faculty of Medicine, University of Ottawa, 145 Carling Avenue, Room 6435, Ottawa, ON, K1Z 7K4, Canada
| | - Stuart Fogel
- Sleep Unit, University of Ottawa Institute of Mental Health Research at The Royal, K1Z 7K4, Ottawa, ON, Canada
| | - Gerhard Jocham
- Faculty of Mathematics and Natural Sciences, Institute of Experimental Psychology, Heinrich Heine University of Düsseldorf, Düsseldorf, Germany
| | - Robert Langner
- Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany
- Institute of Systems Neuroscience, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Adrian M Owen
- Departments of Physiology and Pharmacology and Psychology, Western University, London, ON, N6A 5B7, Canada
| | - Georg Northoff
- The Royal's Institute of Mental Health Research & University of Ottawa, Brain and Mind Research Institute, Centre for Neural Dynamics, Faculty of Medicine, University of Ottawa, 145 Carling Avenue, Room 6435, Ottawa, ON, K1Z 7K4, Canada
- Centre for Cognition and Brain Disorders, Hangzhou Normal University, Tianmu Road 305, Hangzhou, Zhejiang Province, 310013, China
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15
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Türker B, Musat EM, Chabani E, Fonteix-Galet A, Maranci JB, Wattiez N, Pouget P, Sitt J, Naccache L, Arnulf I, Oudiette D. Behavioral and brain responses to verbal stimuli reveal transient periods of cognitive integration of the external world during sleep. Nat Neurosci 2023; 26:1981-1993. [PMID: 37828228 PMCID: PMC10620087 DOI: 10.1038/s41593-023-01449-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/05/2023] [Indexed: 10/14/2023]
Abstract
Sleep has long been considered as a state of behavioral disconnection from the environment, without reactivity to external stimuli. Here we questioned this 'sleep disconnection' dogma by directly investigating behavioral responsiveness in 49 napping participants (27 with narcolepsy and 22 healthy volunteers) engaged in a lexical decision task. Participants were instructed to frown or smile depending on the stimulus type. We found accurate behavioral responses, visible via contractions of the corrugator or zygomatic muscles, in most sleep stages in both groups (except slow-wave sleep in healthy volunteers). Across sleep stages, responses occurred more frequently when stimuli were presented during high cognitive states than during low cognitive states, as indexed by prestimulus electroencephalography. Our findings suggest that transient windows of reactivity to external stimuli exist during bona fide sleep, even in healthy individuals. Such windows of reactivity could pave the way for real-time communication with sleepers to probe sleep-related mental and cognitive processes.
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Affiliation(s)
- Başak Türker
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
| | - Esteban Munoz Musat
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
| | - Emma Chabani
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
| | | | - Jean-Baptiste Maranci
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, Service des Pathologies du Sommeil, National Reference Centre for Narcolepsy, Paris, France
| | - Nicolas Wattiez
- Sorbonne Université, INSERM, Neurophysiologie Respiratoire Expérimentale et Clinique, Paris, France
| | - Pierre Pouget
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
| | - Jacobo Sitt
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
| | - Lionel Naccache
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, Service de Neurophysiologie Clinique, Paris, France
| | - Isabelle Arnulf
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, Service des Pathologies du Sommeil, National Reference Centre for Narcolepsy, Paris, France
| | - Delphine Oudiette
- Sorbonne Université, Institut du Cerveau-Paris Brain Institute-ICM, INSERM, CNRS, Paris, France.
- AP-HP, Hôpital Pitié-Salpêtrière, Service des Pathologies du Sommeil, National Reference Centre for Narcolepsy, Paris, France.
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16
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Liu J, Xia T, Chen D, Yao Z, Zhu M, Antony JW, Lee TMC, Hu X. Item-specific neural representations during human sleep support long-term memory. PLoS Biol 2023; 21:e3002399. [PMID: 37983253 PMCID: PMC10695382 DOI: 10.1371/journal.pbio.3002399] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 12/04/2023] [Accepted: 10/20/2023] [Indexed: 11/22/2023] Open
Abstract
Understanding how individual memories are reactivated during sleep is essential in theorizing memory consolidation. Here, we employed the targeted memory reactivation (TMR) paradigm to unobtrusively replaying auditory memory cues during human participants' slow-wave sleep (SWS). Using representational similarity analysis (RSA) on cue-elicited electroencephalogram (EEG), we found temporally segregated and functionally distinct item-specific neural representations: the early post-cue EEG activity (within 0 to 2,000 ms) contained comparable item-specific representations for memory cues and control cues, signifying effective processing of auditory cues. Critically, the later EEG activity (2,500 to 2,960 ms) showed greater item-specific representations for post-sleep remembered items than for forgotten and control cues, indicating memory reprocessing. Moreover, these later item-specific neural representations were supported by concurrently increased spindles, particularly for items that had not been tested prior to sleep. These findings elucidated how external memory cues triggered item-specific neural representations during SWS and how such representations were linked to successful long-term memory. These results will benefit future research aiming to perturb specific memory episodes during sleep.
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Affiliation(s)
- Jing Liu
- Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hong Kong, People’s Republic of China
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Tao Xia
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Danni Chen
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Ziqing Yao
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Minrui Zhu
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - James W. Antony
- Department of Psychology & Child Development, California Polytechnic State University, San Luis Obispo, California, United States of America
| | - Tatia M. C. Lee
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
- Laboratory of Neuropsychology and Human Neuroscience, Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
| | - Xiaoqing Hu
- The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, People’s Republic of China
- Department of Psychology, The University of Hong Kong, Hong Kong, People’s Republic of China
- HKU-Shenzhen Institute of Research and Innovation, Shenzhen, People’s Republic of China
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17
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Lee J, Chen S, Monfared RV, Derdeyn P, Leong K, Chang T, Beier K, Baldi P, Alachkar A. Reanalysis of primate brain circadian transcriptomics reveals connectivity-related oscillations. iScience 2023; 26:107810. [PMID: 37752952 PMCID: PMC10518731 DOI: 10.1016/j.isci.2023.107810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/22/2023] [Accepted: 08/30/2023] [Indexed: 09/28/2023] Open
Abstract
Research shows that brain circuits controlling vital physiological processes are closely linked with endogenous time-keeping systems. In this study, we aimed to examine oscillatory gene expression patterns of well-characterized neuronal circuits by reanalyzing publicly available transcriptomic data from a spatiotemporal gene expression atlas of a non-human primate. Unexpectedly, brain structures known for regulating circadian processes (e.g., hypothalamic nuclei) did not exhibit robust cycling expression. In contrast, basal ganglia nuclei, not typically associated with circadian physiology, displayed the most dynamic cycling behavior of its genes marked by sharp temporally defined expression peaks. Intriguingly, the mammillary bodies, considered hypothalamic nuclei, exhibited gene expression patterns resembling the basal ganglia, prompting reevaluation of their classification. Our results emphasize the potential for high throughput circadian gene expression analysis to deepen our understanding of the functional synchronization across brain structures that influence physiological processes and resulting complex behaviors.
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Affiliation(s)
- Justine Lee
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Siwei Chen
- Department of Computer Science, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, USA
| | - Roudabeh Vakil Monfared
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Pieter Derdeyn
- Mathematical, Computational, and Systems Biology Program, University of California, Irvine, Irvine, CA, USA
| | - Kenneth Leong
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Tiffany Chang
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
| | - Kevin Beier
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
- Department of Physiology and Biophysics, School of medicine, University of California, Irvine, Irvine, CA, USA
- Department of Neurobiology and Behavior, University of California, Irvine, Irvine, CA 92697-4560, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92697-4560, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
| | - Pierre Baldi
- Department of Computer Science, School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
- Institute for Genomics and Bioinformatics, University of California, Irvine, Irvine, CA, USA
| | - Amal Alachkar
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University of California, Irvine, Irvine, CA, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA 92697, USA
- Institute for Genomics and Bioinformatics, University of California, Irvine, Irvine, CA, USA
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18
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Andrillon T. How we sleep: From brain states to processes. Rev Neurol (Paris) 2023; 179:649-657. [PMID: 37625978 DOI: 10.1016/j.neurol.2023.08.007] [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: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023]
Abstract
All our lives, we alternate between wakefulness and sleep with direct consequences on our ability to interact with our environment, the dynamics and contents of our subjective experience, and our brain activity. Consequently, sleep has been extensively characterised in terms of behavioural, phenomenological, and physiological changes, the latter constituting the gold standard of sleep research. The common view is thus that sleep represents a collection of discrete states with distinct neurophysiological signatures. However, recent findings challenge such a monolithic view of sleep. Indeed, there can be sharp discrepancies in time and space in the activity displayed by different brain regions or networks, making it difficult to assign a global vigilance state to such a mosaic of contrasted dynamics. Viewing sleep as a multidimensional continuum rather than a succession of non-overlapping and mutually exclusive states could account for these local aspects of sleep. Moving away from the focus on sleep states, sleep can also be investigated through the brain processes that are present in sleep, if not necessarily specific to sleep. This focus on processes rather than states allows to see sleep for what it does rather than what it is, avoiding some of the limitations of the state perspective and providing a powerful heuristic to understand sleep. Indeed, what is sleep if not a process itself that makes up wake up every morning with a brain cleaner, leaner and less cluttered.
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Affiliation(s)
- T Andrillon
- Paris Brain Institute, Sorbonne Université, Inserm, CNRS, 75013 Paris, France; Monash Centre for Consciousness & Contemplative Studies, Monash University, Melbourne, VIC 3800, Australia.
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19
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Gao JX, Yan G, Li XX, Xie JF, Spruyt K, Shao YF, Hou YP. The Ponto-Geniculo-Occipital (PGO) Waves in Dreaming: An Overview. Brain Sci 2023; 13:1350. [PMID: 37759951 PMCID: PMC10526299 DOI: 10.3390/brainsci13091350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 09/11/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Rapid eye movement (REM) sleep is the main sleep correlate of dreaming. Ponto-geniculo-occipital (PGO) waves are a signature of REM sleep. They represent the physiological mechanism of REM sleep that specifically limits the processing of external information. PGO waves look just like a message sent from the pons to the lateral geniculate nucleus of the visual thalamus, the occipital cortex, and other areas of the brain. The dedicated visual pathway of PGO waves can be interpreted by the brain as visual information, leading to the visual hallucinosis of dreams. PGO waves are considered to be both a reflection of REM sleep brain activity and causal to dreams due to their stimulation of the cortex. In this review, we summarize the role of PGO waves in potential neural circuits of two major theories, i.e., (1) dreams are generated by the activation of neural activity in the brainstem; (2) PGO waves signaling to the cortex. In addition, the potential physiological functions during REM sleep dreams, such as memory consolidation, unlearning, and brain development and plasticity and mood regulation, are discussed. It is hoped that our review will support and encourage research into the phenomenon of human PGO waves and their possible functions in dreaming.
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Affiliation(s)
- Jin-Xian Gao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
| | - Guizhong Yan
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
| | - Xin-Xuan Li
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
| | - Jun-Fan Xie
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
| | - Karen Spruyt
- NeuroDiderot-INSERM, Université de Paris, 75019 Paris, France;
| | - Yu-Feng Shao
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
| | - Yi-Ping Hou
- Key Laboratory of Preclinical Study for New Drugs of Gansu Province, Departments of Neuroscience, Anatomy, Histology, and Embryology, School of Basic Medical Sciences, Lanzhou University, Lanzhou 730000, China; (J.-X.G.); (G.Y.); (X.-X.L.); (J.-F.X.)
- Sleep Medicine Center of Gansu Provincial Hospital, Lanzhou 730000, China
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20
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Wick A, Rasch B. Targeted memory reactivation during slow-wave sleep vs. sleep stage N2: no significant differences in a vocabulary task. Learn Mem 2023; 30:192-200. [PMID: 37726143 PMCID: PMC10547374 DOI: 10.1101/lm.053683.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/24/2023] [Indexed: 09/21/2023]
Abstract
Sleep supports memory consolidation, and slow-wave sleep (SWS) in particular is assumed to benefit the consolidation of verbal learning material. Re-exposure to previously learned words during SWS with a technique known as targeted memory reactivation (TMR) consistently benefits memory. However, TMR has also been successfully applied during sleep stage N2, though a direct comparison between words selectively reactivated during SWS versus N2 is still missing. Here, we directly compared the effects of N2 TMR and SWS TMR on memory performance in a vocabulary learning task in a within-subject design. Thirty-four healthy young participants (21 in the main sample and 13 in an additional sample) learned 120 Dutch-German word pairs before sleep. Participants in the main sample slept for ∼8 h during the night, while participants in the additional sample slept ∼3 h. We reactivated the Dutch words selectively during N2 and SWS in one single night. Forty words were not cued. Participants in the main sample recalled the German translations of the Dutch words after sleep in the morning, while those in the additional sample did so at 2:00 a.m. As expected, we observed no differences in recall performance between words reactivated during N2 and SWS. However, we failed to find an overall memory benefit of reactivated over nonreactivated words. Detailed time-frequency analyses showed that words played during N2 elicited stronger characteristic oscillatory responses in several frequency bands, including spindle and theta frequencies, compared with SWS. These oscillatory responses did not vary with the memory strengths of individual words. Our results question the robustness and replicability of the TMR benefit on memory using our Dutch vocabulary learning task. We discuss potential boundary conditions for vocabulary reactivation paradigms and, most importantly, see the need for further replication studies, ideally including multiple laboratories and larger sample sizes.
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Affiliation(s)
- Anna Wick
- Department of Psychology, University of Fribourg, Fribourg 1700, Switzerland
| | - Björn Rasch
- Department of Psychology, University of Fribourg, Fribourg 1700, Switzerland
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21
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Northoff G, Scalabrini A, Fogel S. Topographic-dynamic reorganisation model of dreams (TRoD) - A spatiotemporal approach. Neurosci Biobehav Rev 2023; 148:105117. [PMID: 36870584 DOI: 10.1016/j.neubiorev.2023.105117] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 12/13/2022] [Accepted: 02/28/2023] [Indexed: 03/06/2023]
Abstract
Dreams are one of the most bizarre and least understood states of consciousness. Bridging the gap between brain and phenomenology of (un)conscious experience, we propose the Topographic-dynamic Re-organization model of Dreams (TRoD). Topographically, dreams are characterized by a shift towards increased activity and connectivity in the default-mode network (DMN) while they are reduced in the central executive network, including the dorsolateral prefrontal cortex (except in lucid dreaming). This topographic re-organization is accompanied by dynamic changes; a shift towards slower frequencies and longer timescales. This puts dreams dynamically in an intermediate position between awake state and NREM 2/SWS sleep. TRoD proposes that the shift towards DMN and slower frequencies leads to an abnormal spatiotemporal framing of input processing including both internally- and externally-generated inputs (from body and environment). In dreams, a shift away from temporal segregation to temporal integration of inputs results in the often bizarre and highly self-centric mental contents as well as hallucinatory-like states. We conclude that topography and temporal dynamics are core features of the TroD, which may provide the connection of neural and mental activity, e.g., brain and experience during dreams as their "common currency".
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Affiliation(s)
- Georg Northoff
- Faculty of Medicine, Centre for Neural Dynamics, The Royal's Institute of Mental Health Research, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada; Mental Health Centre, Zhejiang University School of Medicine, Hangzhou, China; Centre for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China.
| | - Andrea Scalabrini
- Department of Human and Social Sciences, University of Bergamo, Bergamo, Italy.
| | - Stuart Fogel
- Sleep and Neuroscience, The Royal's Institute of Mental Health Research, Brain and Mind Research Institute and Faculty of Social Sciences, University of Ottawa, Ottawa, ON, Canada.
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22
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Xia T, Yao Z, Guo X, Liu J, Chen D, Liu Q, Paller KA, Hu X. Updating memories of unwanted emotions during human sleep. Curr Biol 2023; 33:309-320.e5. [PMID: 36584677 PMCID: PMC9979073 DOI: 10.1016/j.cub.2022.12.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 10/21/2022] [Accepted: 12/02/2022] [Indexed: 12/30/2022]
Abstract
Post-learning sleep contributes to memory consolidation. Yet it remains contentious whether sleep affords opportunities to modify or update emotional memories, particularly when people would prefer to forget those memories. Here, we attempted to update memories during sleep, using spoken positive words paired with cues to recent memories of aversive events. Affective updating using positive words during human non-rapid eye movement (NREM) sleep, compared with using neutral words instead, reduced negative affective judgments in post-sleep tests, suggesting that the recalled events were perceived as less aversive. Electroencephalogram (EEG) analyses showed that positive words modulated theta and spindle/sigma activity; specifically, to the extent that theta power was larger for the positive words than for the memory cues that followed, participants judged the memory cues less negatively. Moreover, to the extent that sigma power was larger for the positive words than for the memory cues that followed, participants forgot more episodic details about aversive events. Notably, when the onset of individual positive words coincided with the up-phase of slow oscillations (a state characterized by increased cortical excitability during NREM sleep), affective updating was more successful. In sum, we altered the affective content of memories via the strategic pairing of positive words and memory cues during sleep, linked with EEG theta power increases and the slow oscillation up-phase. These findings suggest novel possibilities for modifying unwanted memories during sleep, which would not require people to consciously confront memories that they prefer to avoid.
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Affiliation(s)
- Tao Xia
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Ziqing Yao
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Xue Guo
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu 610068, China
| | - Jing Liu
- Department of Applied Social Sciences, The Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Danni Chen
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Qiang Liu
- Institute of Brain and Psychological Sciences, Sichuan Normal University, Chengdu 610068, China; Brain and Cognitive Neuroscience Research Center, Liaoning Normal University, Dalian 116029, China.
| | - Ken A Paller
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL 60208, USA
| | - Xiaoqing Hu
- Department of Psychology, The State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong SAR, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen 518057, China.
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23
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Uji M, Tamaki M. Sleep, learning, and memory in human research using noninvasive neuroimaging techniques. Neurosci Res 2022; 189:66-74. [PMID: 36572251 DOI: 10.1016/j.neures.2022.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 11/25/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
An accumulating body of evidence indicates that sleep is beneficial for learning and memory. Task performance improves significantly after a period that includes sleep, whereas a lack of sleep nullifies or impairs such improvements. Our current knowledge about sleep's role in learning and memory has been obtained based on studies that were conducted in both animal models and human subjects. Nevertheless, how sleep promotes learning and memory in humans is not fully understood. In this review, we overview our current understating of how sleep may contribute to learning and memory, covering different roles of non-rapid eye movement and rapid eye movement sleep. We then discuss cutting-edge advanced techniques that are currently available, including simultaneous functional magnetic resonance imaging (fMRI) and electroencephalogram (EEG) and simultaneous functional magnetic resonance spectroscopy (fMRS) and EEG measurements, and evaluate how these may contribute to advance the understanding of the role of sleep in human cognition. We also highlight the current limitations and challenges using these methods and discuss ways that may allow us to overcome these limitations.
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Affiliation(s)
- Makoto Uji
- RIKEN Center for Brain Science, Saitama 3510198, Japan
| | - Masako Tamaki
- RIKEN Center for Brain Science, Saitama 3510198, Japan; RIKEN Cluster for Pioneering Research, Saitama 3510198, Japan.
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24
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Ruch S, Schmidig FJ, Knüsel L, Henke K. Closed-loop modulation of local slow oscillations in human NREM sleep. Neuroimage 2022; 264:119682. [PMID: 36240988 DOI: 10.1016/j.neuroimage.2022.119682] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 10/10/2022] [Accepted: 10/11/2022] [Indexed: 11/07/2022] Open
Abstract
Slow-wave sleep is the deep non-rapid eye-movement (NREM) sleep stage that is most relevant for the recuperative function of sleep. Its defining property is the presence of slow oscillations (<2 Hz) in the scalp electroencephalogram (EEG). Slow oscillations are generated by a synchronous back and forth between highly active UP-states and silent DOWN-states in neocortical neurons. Growing evidence suggests that closed-loop sensory stimulation targeted at UP-states of EEG-defined slow oscillations can enhance the slow oscillatory activity, increase sleep depth, and boost sleep's recuperative functions. However, several studies failed to replicate such findings. Failed replications might be due to the use of conventional closed-loop stimulation algorithms that analyze the signal from one single electrode and thereby neglect the fact that slow oscillations vary with respect to their origins, distributions, and trajectories on the scalp. In particular, conventional algorithms nonspecifically target functionally heterogeneous UP-states of distinct origins. After all, slow oscillations at distinct sites of the scalp have been associated with distinct functions. Here we present a novel EEG-based closed-loop stimulation algorithm that allows targeting UP- and DOWN-states of distinct cerebral origins based on topographic analyses of the EEG: the topographic targeting of slow oscillations (TOPOSO) algorithm. We present evidence that the TOPOSO algorithm can detect and target local slow oscillations with specific, predefined voltage maps on the scalp in real-time. When compared to a more conventional, single-channel-based approach, TOPOSO leads to fewer but locally more specific stimulations in a simulation study. In a validation study with napping participants, TOPOSO targets auditory stimulation reliably at local UP-states over frontal, sensorimotor, and centro-parietal regions. Importantly, auditory stimulation temporarily enhanced the targeted local state. However, stimulation then elicited a standard frontal slow oscillation rather than local slow oscillations. The TOPOSO algorithm is suitable for the modulation and the study of the functions of local slow oscillations.
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Affiliation(s)
- Simon Ruch
- Institute for Neuromodulation and Neurotechnology, Department of Neurosurgery and Neurotechnology, University Hospital and University of Tuebingen, Otfried-Müller-Str. 45, Tübingen 72076, Germany; Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland.
| | - Flavio Jean Schmidig
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Leona Knüsel
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Katharina Henke
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
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25
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Aime M, Adamantidis AR. Sleep to Survive Predators. Neurosci Bull 2022; 38:1114-1116. [PMID: 35570232 PMCID: PMC9468192 DOI: 10.1007/s12264-022-00875-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2022] [Accepted: 04/10/2022] [Indexed: 10/18/2022] Open
Affiliation(s)
- Mattia Aime
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, 3010, Bern, Switzerland
- Department of Biomedical Research, University of Bern, 3010, Bern, Switzerland
| | - Antoine R Adamantidis
- Department of Neurology, Zentrum für Experimentelle Neurologie, Inselspital University Hospital Bern, 3010, Bern, Switzerland.
- Department of Biomedical Research, University of Bern, 3010, Bern, Switzerland.
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26
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Abstract
The extent to which we are affected by perceptual input of which we are unaware is widely debated. By measuring neural responses to sensory stimulation, neuroscientific data could complement behavioral results with valuable evidence. Here we review neuroscientific findings of processing of high-level information, as well as interactions with attention and memory. Although the results are mixed, we find initial support for processing object categories and words, possibly to the semantic level, as well as emotional expressions. Robust neural evidence for face individuation and integration of sentences or scenes is lacking. Attention affects the processing of stimuli that are not consciously perceived, and such stimuli may exogenously but not endogenously capture attention when relevant, and be maintained in memory over time. Sources of inconsistency in the literature include variability in control for awareness as well as individual differences, calling for future studies that adopt stricter measures of awareness and probe multiple processes within subjects.
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Affiliation(s)
- Liad Mudrik
- School of Psychological Sciences and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel;
| | - Leon Y Deouell
- Department of Psychology and The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel;
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27
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Sound disrupts sleep-associated brain oscillations in rodents in a meaning-dependent manner. Sci Rep 2022; 12:6051. [PMID: 35410339 PMCID: PMC9001723 DOI: 10.1038/s41598-022-09457-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 03/22/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractSleep is essential but places animals at risk. Filtering acoustic information according to its relevance, a process generally known as sensory gating, is crucial during sleep to ensure a balance between rest and danger detection. The mechanisms of this sensory gating and its specificity are not understood. Here, we tested the effect that sounds of different meaning have on sleep-associated ongoing oscillations. We recorded EEG and EMG from mice during REM and NREM sleep while presenting sounds with or without behavioural relevance. We found that sound presentation per se, in the form of a neutral sound, elicited a weak or no change in the power of sleep-state-dependent EEG during REM and NREM sleep. In contrast, the presentation of a sound previously conditioned in an aversive task, elicited a clear and fast decrease in the EEG power during both sleep phases, suggesting a transition to lighter sleep without awakening. The observed changes generally weakened over training days and were not present in animals that failed to learn. Interestingly, the effect could be generalized to unfamiliar neutral sounds if presented following conditioned training, an effect that depended on sleep phase and sound type. The data demonstrate that sounds are differentially gated during sleep depending on their meaning and that this process is reflected in disruption of sleep-associated brain oscillations without behavioural arousal.
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28
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Koroma M, Elbaz M, Léger D, Kouider S. Learning New Vocabulary Implicitly During Sleep Transfers With Cross-Modal Generalization Into Wakefulness. Front Neurosci 2022; 16:801666. [PMID: 35356055 PMCID: PMC8959773 DOI: 10.3389/fnins.2022.801666] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 02/14/2022] [Indexed: 11/13/2022] Open
Abstract
New information can be learned during sleep but the extent to which we can access this knowledge after awakening is far less understood. Using a novel Associative Transfer Learning paradigm, we show that, after hearing unknown Japanese words with sounds referring to their meaning during sleep, participants could identify the images depicting the meaning of newly acquired Japanese words after awakening (N = 22). Moreover, we demonstrate that this cross-modal generalization is implicit, meaning that participants remain unaware of this knowledge. Using electroencephalography, we further show that frontal slow-wave responses to auditory stimuli during sleep predicted memory performance after awakening. This neural signature of memory formation gradually emerged over the course of the sleep phase, highlighting the dynamics of associative learning during sleep. This study provides novel evidence that the formation of new associative memories can be traced back to the dynamics of slow-wave responses to stimuli during sleep and that their implicit transfer into wakefulness can be generalized across sensory modalities.
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Affiliation(s)
- Matthieu Koroma
- Brain and Consciousness Group (ENS, EHESS, CNRS), Département d’Études Cognitives, École Normale Supérieure, Paris, France
- École Doctorale Cerveau Cognition Comportement, Université Pierre et Marie Curie Sorbonne Universités, Paris, France
| | - Maxime Elbaz
- Université de Paris, APHP, Hôtel-Dieu de Paris, Centre du Sommeil et de la Vigilance, EA 7330 VIFASOM Sommeil-Vigilance-Fatigue et Santé Publique, Paris, France
| | - Damien Léger
- Université de Paris, APHP, Hôtel-Dieu de Paris, Centre du Sommeil et de la Vigilance, EA 7330 VIFASOM Sommeil-Vigilance-Fatigue et Santé Publique, Paris, France
| | - Sid Kouider
- Brain and Consciousness Group (ENS, EHESS, CNRS), Département d’Études Cognitives, École Normale Supérieure, Paris, France
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29
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Wolff A, Berberian N, Golesorkhi M, Gomez-Pilar J, Zilio F, Northoff G. Intrinsic neural timescales: temporal integration and segregation. Trends Cogn Sci 2022; 26:159-173. [PMID: 34991988 DOI: 10.1016/j.tics.2021.11.007] [Citation(s) in RCA: 65] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 11/19/2021] [Accepted: 11/23/2021] [Indexed: 12/11/2022]
Abstract
We are continuously bombarded by external inputs of various timescales from the environment. How does the brain process this multitude of timescales? Recent resting state studies show a hierarchy of intrinsic neural timescales (INT) with a shorter duration in unimodal regions (e.g., visual cortex and auditory cortex) and a longer duration in transmodal regions (e.g., default mode network). This unimodal-transmodal hierarchy is present across acquisition modalities [electroencephalogram (EEG)/magnetoencephalogram (MEG) and fMRI] and can be found in different species and during a variety of different task states. Together, this suggests that the hierarchy of INT is central to the temporal integration (combining successive stimuli) and segregation (separating successive stimuli) of external inputs from the environment, leading to temporal segmentation and prediction in perception and cognition.
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Affiliation(s)
- Annemarie Wolff
- Mind, Brain Imaging, and Neuroethics Research Unit, Institute of Mental Health Research, The Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Nareg Berberian
- Mind, Brain Imaging, and Neuroethics Research Unit, Institute of Mental Health Research, The Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Mehrshad Golesorkhi
- Mind, Brain Imaging, and Neuroethics Research Unit, Institute of Mental Health Research, The Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Javier Gomez-Pilar
- Biomedical Engineering Group, University of Valladolid, Paseo de Belén, 15, 47011 Valladolid, Spain; Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicia, (CIBER-BBN), Madrid, Spain
| | - Federico Zilio
- Department of Philosophy, Sociology, Education, and Applied Psychology, University of Padova, Padua, Italy
| | - Georg Northoff
- Mind, Brain Imaging, and Neuroethics Research Unit, Institute of Mental Health Research, The Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada; Centre for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China; Mental Health Centre, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.
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30
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Walter J. Consciousness as a multidimensional phenomenon: implications for the assessment of disorders of consciousness. Neurosci Conscious 2021; 2021:niab047. [PMID: 34992792 PMCID: PMC8716840 DOI: 10.1093/nc/niab047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 10/19/2021] [Accepted: 12/10/2021] [Indexed: 01/10/2023] Open
Abstract
Disorders of consciousness (DoCs) pose a significant clinical and ethical challenge because they allow for complex forms of conscious experience in patients where intentional behaviour and communication are highly limited or non-existent. There is a pressing need for brain-based assessments that can precisely and accurately characterize the conscious state of individual DoC patients. There has been an ongoing research effort to develop neural measures of consciousness. However, these measures are challenging to validate not only due to our lack of ground truth about consciousness in many DoC patients but also because there is an open ontological question about consciousness. There is a growing, well-supported view that consciousness is a multidimensional phenomenon that cannot be fully described in terms of the theoretical construct of hierarchical, easily ordered conscious levels. The multidimensional view of consciousness challenges the utility of levels-based neural measures in the context of DoC assessment. To examine how these measures may map onto consciousness as a multidimensional phenomenon, this article will investigate a range of studies where they have been applied in states other than DoC and where more is known about conscious experience. This comparative evidence suggests that measures of conscious level are more sensitive to some dimensions of consciousness than others and cannot be assumed to provide a straightforward hierarchical characterization of conscious states. Elevated levels of brain complexity, for example, are associated with conscious states characterized by a high degree of sensory richness and minimal attentional constraints, but are suboptimal for goal-directed behaviour and external responsiveness. Overall, this comparative analysis indicates that there are currently limitations to the use of these measures as tools to evaluate consciousness as a multidimensional phenomenon and that the relationship between these neural signatures and phenomenology requires closer scrutiny.
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Affiliation(s)
- Jasmine Walter
- Cognition and Philosophy Lab, 21 Chancellor’s Walk, Monash University, Melbourne, VIC 3800, Australia
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31
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Ruch S, Alain Züst M, Henke K. Sleep-learning impairs subsequent awake-learning. Neurobiol Learn Mem 2021; 187:107569. [PMID: 34863922 DOI: 10.1016/j.nlm.2021.107569] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 09/21/2021] [Accepted: 11/26/2021] [Indexed: 01/11/2023]
Abstract
Although we can learn new information while asleep, we usually cannot consciously remember the sleep-formed memories - presumably because learning occurred in an unconscious state. Here, we ask whether sleep-learning expedites the subsequent awake-learning of the same information. To answer this question, we reanalyzed data (Züst et al., 2019, Curr Biol) from napping participants, who learned new semantic associations between pseudowords and translation-words (guga-ship) while in slow-wave sleep. They retrieved sleep-formed associations unconsciously on an implicit memory test following awakening. Then, participants took five runs of paired-associative learning to probe carry-over effects of sleep-learning on awake-learning. Surprisingly, sleep-learning diminished awake-learning when participants learned semantic associations that were congruent to sleep-learned associations (guga-boat). Yet, learning associations that conflicted with sleep-learned associations (guga-coin) was unimpaired relative to learning new associations (resun-table; baseline). We speculate that the impeded wake-learning originated in a deficient synaptic downscaling and resulting synaptic saturation in neurons that were activated during both sleep-learning and awake-learning.
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Affiliation(s)
- Simon Ruch
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland.
| | - Marc Alain Züst
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
| | - Katharina Henke
- Cognitive Neuroscience of Memory and Consciousness, Institute of Psychology, University of Bern, Fabrikstrasse 8, 3012 Bern, Switzerland
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32
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Osorio-Forero A, Cardis R, Vantomme G, Guillaume-Gentil A, Katsioudi G, Devenoges C, Fernandez LMJ, Lüthi A. Noradrenergic circuit control of non-REM sleep substates. Curr Biol 2021; 31:5009-5023.e7. [PMID: 34648731 DOI: 10.1016/j.cub.2021.09.041] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 08/09/2021] [Accepted: 09/15/2021] [Indexed: 12/13/2022]
Abstract
To understand what makes sleep vulnerable in disease, it is useful to look at how wake-promoting mechanisms affect healthy sleep. Wake-promoting neuronal activity is inhibited during non-rapid-eye-movement sleep (NREMS). However, sensory vigilance persists in NREMS in animals and humans, suggesting that wake promotion could remain functional. Here, we demonstrate that consolidated mouse NREMS is a brain state with recurrent fluctuations of the wake-promoting neurotransmitter noradrenaline on the ∼50-s timescale in the thalamus. These fluctuations occurred around mean noradrenaline levels greater than the ones of quiet wakefulness, while noradrenaline (NA) levels declined steeply in REMS. They coincided with a clustering of sleep spindle rhythms in the forebrain and with heart-rate variations, both of which are correlates of sensory arousability. We addressed the origins of these fluctuations by using closed-loop optogenetic locus coeruleus (LC) activation or inhibition timed to moments of low and high spindle activity during NREMS. We could suppress, lock, or entrain sleep-spindle clustering and heart-rate variations, suggesting that both fore- and hindbrain-projecting LC neurons show coordinated infraslow activity variations in natural NREMS. Noradrenergic modulation of thalamic, but not cortical, circuits was required for sleep-spindle clustering and involved NA release into primary sensory and reticular thalamic nuclei that activated both α1- and β-adrenergic receptors to cause slowly decaying membrane depolarizations. Noradrenergic signaling by LC constitutes a vigilance-promoting mechanism that renders mammalian NREMS vulnerable to disruption on the close-to-minute timescale through sustaining thalamocortical and autonomic sensory arousability. VIDEO ABSTRACT.
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Affiliation(s)
- Alejandro Osorio-Forero
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Romain Cardis
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Gil Vantomme
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Aurélie Guillaume-Gentil
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Georgia Katsioudi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Christiane Devenoges
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Laura M J Fernandez
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, 1005 Lausanne, Switzerland.
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33
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Van De Poll MN, van Swinderen B. Balancing Prediction and Surprise: A Role for Active Sleep at the Dawn of Consciousness? Front Syst Neurosci 2021; 15:768762. [PMID: 34803618 PMCID: PMC8602873 DOI: 10.3389/fnsys.2021.768762] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 10/08/2021] [Indexed: 11/14/2022] Open
Abstract
The brain is a prediction machine. Yet the world is never entirely predictable, for any animal. Unexpected events are surprising, and this typically evokes prediction error signatures in mammalian brains. In humans such mismatched expectations are often associated with an emotional response as well, and emotional dysregulation can lead to cognitive disorders such as depression or schizophrenia. Emotional responses are understood to be important for memory consolidation, suggesting that positive or negative 'valence' cues more generally constitute an ancient mechanism designed to potently refine and generalize internal models of the world and thereby minimize prediction errors. On the other hand, abolishing error detection and surprise entirely (as could happen by generalization or habituation) is probably maladaptive, as this might undermine the very mechanism that brains use to become better prediction machines. This paradoxical view of brain function as an ongoing balance between prediction and surprise suggests a compelling approach to study and understand the evolution of consciousness in animals. In particular, this view may provide insight into the function and evolution of 'active' sleep. Here, we propose that active sleep - when animals are behaviorally asleep but their brain seems awake - is widespread beyond mammals and birds, and may have evolved as a mechanism for optimizing predictive processing in motile creatures confronted with constantly changing environments. To explore our hypothesis, we progress from humans to invertebrates, investigating how a potential role for rapid eye movement (REM) sleep in emotional regulation in humans could be re-examined as a conserved sleep function that co-evolved alongside selective attention to maintain an adaptive balance between prediction and surprise. This view of active sleep has some interesting implications for the evolution of subjective awareness and consciousness in animals.
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Affiliation(s)
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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34
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Pérez P, Madsen J, Banellis L, Türker B, Raimondo F, Perlbarg V, Valente M, Niérat MC, Puybasset L, Naccache L, Similowski T, Cruse D, Parra LC, Sitt JD. Conscious processing of narrative stimuli synchronizes heart rate between individuals. Cell Rep 2021; 36:109692. [PMID: 34525363 DOI: 10.1016/j.celrep.2021.109692] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 06/15/2021] [Accepted: 08/19/2021] [Indexed: 10/20/2022] Open
Abstract
Heart rate has natural fluctuations that are typically ascribed to autonomic function. Recent evidence suggests that conscious processing can affect the timing of the heartbeat. We hypothesized that heart rate is modulated by conscious processing and therefore dependent on attentional focus. To test this, we leverage the observation that neural processes synchronize between subjects by presenting an identical narrative stimulus. As predicted, we find significant inter-subject correlation of heart rate (ISC-HR) when subjects are presented with an auditory or audiovisual narrative. Consistent with our hypothesis, we find that ISC-HR is reduced when subjects are distracted from the narrative, and higher ISC-HR predicts better recall of the narrative. Finally, patients with disorders of consciousness have lower ISC-HR, as compared to healthy individuals. We conclude that heart rate fluctuations are partially driven by conscious processing, depend on attentional state, and may represent a simple metric to assess conscious state in unresponsive patients.
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Affiliation(s)
- Pauline Pérez
- Paris Brain Institute, ICM, 75013 Paris, France; Inserm U 1127, 75013 Paris, France; CNRS UMR 7225, 75013 Paris, France
| | - Jens Madsen
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Leah Banellis
- School of Psychology, University of Birmingham, Birmingham B15 2TT, England; Centre for Human Brain Health, University of Birmingham, Birmingham B15 2TT, England
| | - Bașak Türker
- Paris Brain Institute, ICM, 75013 Paris, France; Inserm U 1127, 75013 Paris, France; CNRS UMR 7225, 75013 Paris, France
| | | | - Vincent Perlbarg
- Bioinformatics and Biostatistics Core Facility, iCONICS, IHU-A-ICM, Institut du Cerveau et de la Moelle épinière, Paris, France
| | | | - Marie-Cécile Niérat
- Sorbonne Université, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, 75005 Paris, France
| | - Louis Puybasset
- Department of Anesthesia and Intensive Care, Pitié-Salpetrière Hospital, Paris, France; Sorbonne Université, CNRS, INSERM, Laboratoire d'Imagerie Biomédicale, LIB, Paris, France
| | - Lionel Naccache
- Paris Brain Institute, ICM, 75013 Paris, France; Inserm U 1127, 75013 Paris, France; CNRS UMR 7225, 75013 Paris, France; Department of Neurophysiology, Hôpital de la Pitié-Salpetrière, AP-HP, 75013 Paris, France; Faculté de Médecine Pitié-Salpêtrière, Sorbonne Université, 75013 Paris, France
| | - Thomas Similowski
- Sorbonne Université, INSERM, UMRS1158 Neurophysiologie Respiratoire Expérimentale et Clinique, 75005 Paris, France; AP-HP, Groupe Hospitalier Universitaire APHP-Sorbonne Université, site Pitié-Salpêtrière, Service de Pneumologie, Médecine Intensive et Réanimation (Département R3S), 75013 Paris, France
| | - Damian Cruse
- School of Psychology, University of Birmingham, Birmingham B15 2TT, England; Centre for Human Brain Health, University of Birmingham, Birmingham B15 2TT, England
| | - Lucas C Parra
- Department of Biomedical Engineering, City College of New York, New York, NY, USA.
| | - Jacobo D Sitt
- Paris Brain Institute, ICM, 75013 Paris, France; Inserm U 1127, 75013 Paris, France; CNRS UMR 7225, 75013 Paris, France.
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35
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Sifuentes-Ortega R, Lenc T, Nozaradan S, Peigneux P. Partially Preserved Processing of Musical Rhythms in REM but Not in NREM Sleep. Cereb Cortex 2021; 32:1508-1519. [PMID: 34491309 DOI: 10.1093/cercor/bhab303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The extent of high-level perceptual processing during sleep remains controversial. In wakefulness, perception of periodicities supports the emergence of high-order representations such as the pulse-like meter perceived while listening to music. Electroencephalography (EEG) frequency-tagged responses elicited at envelope frequencies of musical rhythms have been shown to provide a neural representation of rhythm processing. Specifically, responses at frequencies corresponding to the perceived meter are enhanced over responses at meter-unrelated frequencies. This selective enhancement must rely on higher-level perceptual processes, as it occurs even in irregular (i.e., syncopated) rhythms where meter frequencies are not prominent input features, thus ruling out acoustic confounds. We recorded EEG while presenting a regular (unsyncopated) and an irregular (syncopated) rhythm across sleep stages and wakefulness. Our results show that frequency-tagged responses at meter-related frequencies of the rhythms were selectively enhanced during wakefulness but attenuated across sleep states. Most importantly, this selective attenuation occurred even in response to the irregular rhythm, where meter-related frequencies were not prominent in the stimulus, thus suggesting that neural processes selectively enhancing meter-related frequencies during wakefulness are weakened during rapid eye movement (REM) and further suppressed in non-rapid eye movement (NREM) sleep. These results indicate preserved processing of low-level acoustic properties but limited higher-order processing of auditory rhythms during sleep.
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Affiliation(s)
- Rebeca Sifuentes-Ortega
- UR2NF - Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition & Neurosciences, and UNI - ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
| | - Tomas Lenc
- Institute of Neuroscience (IONS), Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Sylvie Nozaradan
- Institute of Neuroscience (IONS), Université Catholique de Louvain, 1200 Brussels, Belgium
| | - Philippe Peigneux
- UR2NF - Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition & Neurosciences, and UNI - ULB Neuroscience Institute, Université Libre de Bruxelles (ULB), 1050 Brussels, Belgium
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36
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Golesorkhi M, Gomez-Pilar J, Zilio F, Berberian N, Wolff A, Yagoub MCE, Northoff G. The brain and its time: intrinsic neural timescales are key for input processing. Commun Biol 2021; 4:970. [PMID: 34400800 PMCID: PMC8368044 DOI: 10.1038/s42003-021-02483-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 07/19/2021] [Indexed: 02/07/2023] Open
Abstract
We process and integrate multiple timescales into one meaningful whole. Recent evidence suggests that the brain displays a complex multiscale temporal organization. Different regions exhibit different timescales as described by the concept of intrinsic neural timescales (INT); however, their function and neural mechanisms remains unclear. We review recent literature on INT and propose that they are key for input processing. Specifically, they are shared across different species, i.e., input sharing. This suggests a role of INT in encoding inputs through matching the inputs' stochastics with the ongoing temporal statistics of the brain's neural activity, i.e., input encoding. Following simulation and empirical data, we point out input integration versus segregation and input sampling as key temporal mechanisms of input processing. This deeply grounds the brain within its environmental and evolutionary context. It carries major implications in understanding mental features and psychiatric disorders, as well as going beyond the brain in integrating timescales into artificial intelligence.
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Affiliation(s)
- Mehrshad Golesorkhi
- grid.28046.380000 0001 2182 2255School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Canada ,grid.28046.380000 0001 2182 2255Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health, Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Javier Gomez-Pilar
- grid.5239.d0000 0001 2286 5329Biomedical Engineering Group, University of Valladolid, Valladolid, Spain ,grid.413448.e0000 0000 9314 1427Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina, (CIBER-BBN), Madrid, Spain
| | - Federico Zilio
- grid.5608.b0000 0004 1757 3470Department of Philosophy, Sociology, Education and Applied Psychology, University of Padova, Padua, Italy
| | - Nareg Berberian
- grid.28046.380000 0001 2182 2255Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health, Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Annemarie Wolff
- grid.28046.380000 0001 2182 2255Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health, Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada
| | - Mustapha C. E. Yagoub
- grid.28046.380000 0001 2182 2255School of Electrical Engineering and Computer Science, University of Ottawa, Ottawa, Canada
| | - Georg Northoff
- grid.28046.380000 0001 2182 2255Mind, Brain Imaging and Neuroethics Research Unit, Institute of Mental Health, Royal Ottawa Mental Health Centre and University of Ottawa, Ottawa, Canada ,grid.410595.c0000 0001 2230 9154Centre for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China ,grid.13402.340000 0004 1759 700XMental Health Centre, Zhejiang University School of Medicine, Hangzhou, Zhejiang China
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37
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Andrillon T, Burns A, Mackay T, Windt J, Tsuchiya N. Predicting lapses of attention with sleep-like slow waves. Nat Commun 2021; 12:3657. [PMID: 34188023 PMCID: PMC8241869 DOI: 10.1038/s41467-021-23890-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 04/21/2021] [Indexed: 11/10/2022] Open
Abstract
Attentional lapses occur commonly and are associated with mind wandering, where focus is turned to thoughts unrelated to ongoing tasks and environmental demands, or mind blanking, where the stream of consciousness itself comes to a halt. To understand the neural mechanisms underlying attentional lapses, we studied the behaviour, subjective experience and neural activity of healthy participants performing a task. Random interruptions prompted participants to indicate their mental states as task-focused, mind-wandering or mind-blanking. Using high-density electroencephalography, we report here that spatially and temporally localized slow waves, a pattern of neural activity characteristic of the transition toward sleep, accompany behavioural markers of lapses and preceded reports of mind wandering and mind blanking. The location of slow waves could distinguish between sluggish and impulsive behaviours, and between mind wandering and mind blanking. Our results suggest attentional lapses share a common physiological origin: the emergence of local sleep-like activity within the awake brain.
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Affiliation(s)
- Thomas Andrillon
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia.
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Paris, France.
| | - Angus Burns
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Teigane Mackay
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Jennifer Windt
- Philosophy Department, Monash University, Melbourne, VIC, Australia
| | - Naotsugu Tsuchiya
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
- Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), Suita, Osaka, Japan
- Advanced Telecommunications Research Computational Neuroscience Laboratories, Soraku-gun, Kyoto, Japan
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38
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Betta M, Handjaras G, Leo A, Federici A, Farinelli V, Ricciardi E, Siclari F, Meletti S, Ballotta D, Benuzzi F, Bernardi G. Cortical and subcortical hemodynamic changes during sleep slow waves in human light sleep. Neuroimage 2021; 236:118117. [PMID: 33940148 DOI: 10.1016/j.neuroimage.2021.118117] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 04/09/2021] [Accepted: 04/18/2021] [Indexed: 12/22/2022] Open
Abstract
EEG slow waves, the hallmarks of NREM sleep are thought to be crucial for the regulation of several important processes, including learning, sensory disconnection and the removal of brain metabolic wastes. Animal research indicates that slow waves may involve complex interactions within and between cortical and subcortical structures. Conventional EEG in humans, however, has a low spatial resolution and is unable to accurately describe changes in the activity of subcortical and deep cortical structures. To overcome these limitations, here we took advantage of simultaneous EEG-fMRI recordings to map cortical and subcortical hemodynamic (BOLD) fluctuations time-locked to slow waves of light sleep. Recordings were performed in twenty healthy adults during an afternoon nap. Slow waves were associated with BOLD-signal increases in the posterior brainstem and in portions of thalamus and cerebellum characterized by preferential functional connectivity with limbic and somatomotor areas, respectively. At the cortical level, significant BOLD-signal decreases were instead found in several areas, including insula and somatomotor cortex. Specifically, a slow signal increase preceded slow-wave onset and was followed by a delayed, stronger signal decrease. Similar hemodynamic changes were found to occur at different delays across most cortical brain areas, mirroring the propagation of electrophysiological slow waves, from centro-frontal to inferior temporo-occipital cortices. Finally, we found that the amplitude of electrophysiological slow waves was positively related to the magnitude and inversely related to the delay of cortical and subcortical BOLD-signal changes. These regional patterns of brain activity are consistent with theoretical accounts of the functions of sleep slow waves.
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Affiliation(s)
- Monica Betta
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy
| | - Giacomo Handjaras
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy
| | - Andrea Leo
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy
| | - Alessandra Federici
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy
| | - Valentina Farinelli
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Emiliano Ricciardi
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy
| | - Francesca Siclari
- Center for Investigation and Research on Sleep, Lausanne University Hospital, Lausanne, Switzerland
| | - Stefano Meletti
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy; Neurology Dept., Azienda Ospedaliera Universitaria di Modena, Modena, Italy
| | - Daniela Ballotta
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Francesca Benuzzi
- Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Giulio Bernardi
- MoMiLab Research Unit, IMT School for Advanced Studies Lucca, Piazza San Francesco, 19, Lucca 55100, Italy.
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39
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Rosenthal ZP, Raut RV, Bowen RM, Snyder AZ, Culver JP, Raichle ME, Lee JM. Peripheral sensory stimulation elicits global slow waves by recruiting somatosensory cortex bilaterally. Proc Natl Acad Sci U S A 2021; 118:e2021252118. [PMID: 33597303 PMCID: PMC7923673 DOI: 10.1073/pnas.2021252118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Slow waves (SWs) are globally propagating, low-frequency (0.5- to 4-Hz) oscillations that are prominent during sleep and anesthesia. SWs are essential to neural plasticity and memory. However, much remains unknown about the mechanisms coordinating SW propagation at the macroscale. To assess SWs in the context of macroscale networks, we recorded cortical activity in awake and ketamine/xylazine-anesthetized mice using widefield optical imaging with fluorescent calcium indicator GCaMP6f. We demonstrate that unilateral somatosensory stimulation evokes bilateral waves that travel across the cortex with state-dependent trajectories. Under anesthesia, we observe that rhythmic stimuli elicit globally resonant, front-to-back propagating SWs. Finally, photothrombotic lesions of S1 show that somatosensory-evoked global SWs depend on bilateral recruitment of homotopic primary somatosensory cortices. Specifically, unilateral lesions of S1 disrupt somatosensory-evoked global SW initiation from either hemisphere, while spontaneous SWs are largely unchanged. These results show that evoked SWs may be triggered by bilateral activation of specific, homotopically connected cortical networks.
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Affiliation(s)
- Zachary P Rosenthal
- Medical Scientist Training Program, Washington University School of Medicine, St. Louis, MO 63110;
- Graduate Program of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110
| | - Ryan V Raut
- Graduate Program of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Ryan M Bowen
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110
| | - Abraham Z Snyder
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110
| | - Joseph P Culver
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110
- Department of Physics, Washington University School of Medicine, St. Louis, MO 63110
| | - Marcus E Raichle
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110
| | - Jin-Moo Lee
- Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110;
- Department of Radiology, Washington University School of Medicine, St. Louis, MO 63110
- Department of Biomedical Engineering, Washington University School of Medicine, St. Louis, MO 63110
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40
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Konkoly KR, Appel K, Chabani E, Mangiaruga A, Gott J, Mallett R, Caughran B, Witkowski S, Whitmore NW, Mazurek CY, Berent JB, Weber FD, Türker B, Leu-Semenescu S, Maranci JB, Pipa G, Arnulf I, Oudiette D, Dresler M, Paller KA. Real-time dialogue between experimenters and dreamers during REM sleep. Curr Biol 2021; 31:1417-1427.e6. [PMID: 33607035 PMCID: PMC8162929 DOI: 10.1016/j.cub.2021.01.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2020] [Revised: 12/08/2020] [Accepted: 01/08/2021] [Indexed: 12/14/2022]
Abstract
Dreams take us to a different reality, a hallucinatory world that feels as real as any waking experience. These often-bizarre episodes are emblematic of human sleep but have yet to be adequately explained. Retrospective dream reports are subject to distortion and forgetting, presenting a fundamental challenge for neuroscientific studies of dreaming. Here we show that individuals who are asleep and in the midst of a lucid dream (aware of the fact that they are currently dreaming) can perceive questions from an experimenter and provide answers using electrophysiological signals. We implemented our procedures for two-way communication during polysomnographically verified rapid-eye-movement (REM) sleep in 36 individuals. Some had minimal prior experience with lucid dreaming, others were frequent lucid dreamers, and one was a patient with narcolepsy who had frequent lucid dreams. During REM sleep, these individuals exhibited various capabilities, including performing veridical perceptual analysis of novel information, maintaining information in working memory, computing simple answers, and expressing volitional replies. Their responses included distinctive eye movements and selective facial muscle contractions, constituting correctly answered questions on 29 occasions across 6 of the individuals tested. These repeated observations of interactive dreaming, documented by four independent laboratory groups, demonstrate that phenomenological and cognitive characteristics of dreaming can be interrogated in real time. This relatively unexplored communication channel can enable a variety of practical applications and a new strategy for the empirical exploration of dreams. Scientific investigations of dreaming have been hampered by the delay between a dream and when people report on their dream, and by a change in state from sleep to wake. To overcome this problem, Konkoly et al. show that individuals in REM sleep can perceive and answer an experimenter’s questions, allowing for real-time communication about a dream.
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Affiliation(s)
- Karen R Konkoly
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Kristoffer Appel
- Institute of Cognitive Science, Osnabrück University, Osnabrück, Germany; Institute of Sleep and Dream Technologies, Hamburg, Germany
| | - Emma Chabani
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France
| | - Anastasia Mangiaruga
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands; Department of Medical and Surgical Sciences, University of Bologna, Bologna, Italy
| | - Jarrod Gott
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Remington Mallett
- Department of Psychology, University of Texas at Austin, Austin, TX, USA
| | - Bruce Caughran
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Sarah Witkowski
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Nathan W Whitmore
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Christopher Y Mazurek
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA
| | | | - Frederik D Weber
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Başak Türker
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France
| | - Smaranda Leu-Semenescu
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Sleep Disorders Department, Paris, France
| | - Jean-Baptiste Maranci
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Sleep Disorders Department, Paris, France
| | - Gordon Pipa
- Institute of Cognitive Science, Osnabrück University, Osnabrück, Germany
| | - Isabelle Arnulf
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Sleep Disorders Department, Paris, France
| | - Delphine Oudiette
- Institut du Cerveau - Paris Brain Institute - ICM, Sorbonne Université, Inserm, CNRS, Paris, France
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behavior, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Ken A Paller
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, IL, USA.
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41
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Tainton-Heap LAL, Kirszenblat LC, Notaras ET, Grabowska MJ, Jeans R, Feng K, Shaw PJ, van Swinderen B. A Paradoxical Kind of Sleep in Drosophila melanogaster. Curr Biol 2020; 31:578-590.e6. [PMID: 33238155 DOI: 10.1016/j.cub.2020.10.081] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 09/14/2020] [Accepted: 10/27/2020] [Indexed: 01/01/2023]
Abstract
The dynamic nature of sleep in many animals suggests distinct stages that serve different functions. Genetic sleep induction methods in animal models provide a powerful way to disambiguate these stages and functions, although behavioral methods alone are insufficient to accurately identify what kind of sleep is being engaged. In Drosophila, activation of the dorsal fan-shaped body (dFB) promotes sleep, but it remains unclear what kind of sleep this is, how the rest of the fly brain is behaving, or if any specific sleep functions are being achieved. Here, we developed a method to record calcium activity from thousands of neurons across a volume of the fly brain during spontaneous sleep and compared this to dFB-induced sleep. We found that spontaneous sleep typically transitions from an active "wake-like" stage to a less active stage. In contrast, optogenetic activation of the dFB promotes sustained wake-like levels of neural activity even though flies become unresponsive to mechanical stimuli. When we probed flies with salient visual stimuli, we found that the activity of visually responsive neurons in the central brain was blocked by transient dFB activation, confirming an acute disconnect from the external environment. Prolonged optogenetic dFB activation nevertheless achieved a key sleep function by correcting visual attention defects brought on by sleep deprivation. These results suggest that dFB activation promotes a distinct form of sleep in Drosophila, where brain activity appears similar to wakefulness, but responsiveness to external sensory stimuli is profoundly suppressed.
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Affiliation(s)
- Lucy A L Tainton-Heap
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Leonie C Kirszenblat
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Eleni T Notaras
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Martyna J Grabowska
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Rhiannon Jeans
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kai Feng
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Paul J Shaw
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Bruno van Swinderen
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
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42
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Paller KA, Creery JD, Schechtman E. Memory and Sleep: How Sleep Cognition Can Change the Waking Mind for the Better. Annu Rev Psychol 2020; 72:123-150. [PMID: 32946325 DOI: 10.1146/annurev-psych-010419-050815] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The memories that we retain can serve many functions. They guide our future actions, form a scaffold for constructing the self, and continue to shape both the self and the way we perceive the world. Although most memories we acquire each day are forgotten, those integrated within the structure of multiple prior memories tend to endure. A rapidly growing body of research is steadily elucidating how the consolidation of memories depends on their reactivation during sleep. Processing memories during sleep not only helps counteract their weakening but also supports problem solving, creativity, and emotional regulation. Yet, sleep-based processing might become maladaptive, such as when worries are excessively revisited. Advances in research on memory and sleep can thus shed light on how this processing influences our waking life, which can further inspire the development of novel strategies for decreasing detrimental rumination-like activity during sleep and for promoting beneficial sleep cognition.
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Affiliation(s)
- Ken A Paller
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
| | - Jessica D Creery
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
| | - Eitan Schechtman
- Department of Psychology and Cognitive Neuroscience Program, Northwestern University, Evanston, Illinois 60208, USA; , ,
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