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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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2
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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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3
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Khazaei M, Raeisi K, Vanhatalo S, Zappasodi F, Comani S, Tokariev A. Neonatal cortical activity organizes into transient network states that are affected by vigilance states and brain injury. Neuroimage 2023; 279:120342. [PMID: 37619792 DOI: 10.1016/j.neuroimage.2023.120342] [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: 03/18/2023] [Revised: 08/11/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023] Open
Abstract
Early neurodevelopment is critically dependent on the structure and dynamics of spontaneous neuronal activity; however, the natural organization of newborn cortical networks is poorly understood. Recent adult studies suggest that spontaneous cortical activity exhibits discrete network states with physiological correlates. Here, we studied newborn cortical activity during sleep using hidden Markov modeling to determine the presence of such discrete neonatal cortical states (NCS) in 107 newborn infants, with 47 of them presenting with a perinatal brain injury. Our results show that neonatal cortical activity organizes into four discrete NCSs that are present in both cardinal sleep states of a newborn infant, active and quiet sleep, respectively. These NCSs exhibit state-specific spectral and functional network characteristics. The sleep states exhibit different NCS dynamics, with quiet sleep presenting higher fronto-temporal activity and a stronger brain-wide neuronal coupling. Brain injury was associated with prolonged lifetimes of the transient NCSs, suggesting lowered dynamics, or flexibility, in the cortical networks. Taken together, the findings suggest that spontaneously occurring transient network states are already present at birth, with significant physiological and pathological correlates; this NCS analysis framework can be fully automatized, and it holds promise for offering an objective, global level measure of early brain function for benchmarking neurodevelopmental or clinical research.
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Affiliation(s)
- Mohammad Khazaei
- Department of Neurosciences, Imaging and Clinical Sciences, University "Gabriele d'Annunzio" of Chieti-Pescara, ITAB building, 3rd floor, room 314, Chieti, Via dei Vestini, Italy.
| | - Khadijeh Raeisi
- Department of Neurosciences, Imaging and Clinical Sciences, University "Gabriele d'Annunzio" of Chieti-Pescara, ITAB building, 3rd floor, room 314, Chieti, Via dei Vestini, Italy
| | - Sampsa Vanhatalo
- BABA center, Pediatric Research Center, Departments of Clinical Neurophysiology and Physiology, Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
| | - Filippo Zappasodi
- Department of Neurosciences, Imaging and Clinical Sciences, University "Gabriele d'Annunzio" of Chieti-Pescara, ITAB building, 3rd floor, room 314, Chieti, Via dei Vestini, Italy; Institute for Advanced Biomedical Technologies, University "Gabriele d'Annunzio" of Chieti-Pescara, Chieti, Italy
| | - Silvia Comani
- Department of Neurosciences, Imaging and Clinical Sciences, University "Gabriele d'Annunzio" of Chieti-Pescara, ITAB building, 3rd floor, room 314, Chieti, Via dei Vestini, Italy; Behavioral Imaging and Neural Dynamics Center, University "Gabriele d'Annunzio" of Chieti-Pescara, Chieti, Italy
| | - Anton Tokariev
- BABA center, Pediatric Research Center, Departments of Clinical Neurophysiology and Physiology, Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
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4
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Onoda K, Akama H. Complex of global functional network as the core of consciousness. Neurosci Res 2023; 190:67-77. [PMID: 36535365 DOI: 10.1016/j.neures.2022.12.007] [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: 05/09/2022] [Revised: 11/20/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Finding the neural basis of consciousness is challenging, and the distribution location of the core of consciousness remains inconclusive. Integrated information theory (IIT) argues that the posterior part of the brain is the hot zone of consciousness, especially phenological consciousness. The IIT has proposed a "main complex", a set of elements determined such that the information loss in a hierarchical partition approach is the largest among those of any other supersets and subsets, as the core of consciousness in a dynamic system. This approach may be applicable not only to phenomenal but also to access-consciousness. This study estimated the main complex of brain dynamics using functional magnetic resonance imaging in Human Connectome Project (HCP) and sleep datasets. The complex analyses revealed the common networks across various tasks and rest-state in HCP, composed of executive control, salience, and dorsal/ventral attention networks. The set of networks of the main complex was maintained during sleep. However, compared with the wakefulness stage, the amount of information of these networks and the default mode network, was reduced for the hypnagogic stage. The global interconnected structure composed of major functional networks can comprise the core of consciousness.
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Affiliation(s)
- Keiichi Onoda
- Department of Psychology, Otemon Gakuin University, Ibaraki, Osaka 567-8502, Japan.
| | - Hiroyuki Akama
- Department of Life Science and Technology, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan
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5
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Simor P, Peigneux P, Bódizs R. Sleep and dreaming in the light of reactive and predictive homeostasis. Neurosci Biobehav Rev 2023; 147:105104. [PMID: 36804397 DOI: 10.1016/j.neubiorev.2023.105104] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/07/2023] [Accepted: 02/16/2023] [Indexed: 02/19/2023]
Abstract
Dreams are often viewed as fascinating but irrelevant mental epihenomena of the sleeping mind with questionable functional relevance. Despite long hours of oneiric activity, and high individual differences in dream recall, dreams are lost into oblivion. Here, we conceptualize dreaming and dream amnesia as inherent aspects of the reactive and predictive homeostatic functions of sleep. Mental activity during sleep conforms to the interplay of restorative processes and future anticipation, and particularly during the second half of the night, it unfolds as a special form of non-constrained, self-referent, and future-oriented cognitive process. Awakening facilitates constrained, goal-directed prospection that competes for shared neural resources with dream production and dream recall, and contributes to dream amnesia. We present the neurophysiological aspects of reactive and predictive homeostasis during sleep, highlighting the putative role of cortisol in predictive homeostasis and forgetting dreams. The theoretical and methodological aspects of our proposal are discussed in relation to the study of dreaming, dream recall, and sleep-related cognitive processes.
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Affiliation(s)
- Péter Simor
- Institute of Psychology, ELTE, Eötvös Loránd University, Budapest, Hungary; UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Philippe Peigneux
- UR2NF, Neuropsychology and Functional Neuroimaging Research Unit at CRCN - Center for Research in Cognition and Neurosciences and UNI - ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
| | - Róbert Bódizs
- Institute of Behavioural Sciences, Semmelweis University, Budapest, Hungary.
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6
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Verga L, D'Este G, Cassani S, Leitner C, Kotz SA, Ferini-Strambi L, Galbiati A. Sleeping with time in mind? A literature review and a proposal for a screening questionnaire on self-awakening. PLoS One 2023; 18:e0283221. [PMID: 36952462 PMCID: PMC10035927 DOI: 10.1371/journal.pone.0283221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 03/03/2023] [Indexed: 03/25/2023] Open
Abstract
Some people report being able to spontaneously "time" the end of their sleep. This ability to self-awaken challenges the idea of sleep as a passive cognitive state. Yet, current evidence on this phenomenon is limited, partly because of the varied definitions of self-awakening and experimental approaches used to study it. Here, we provide a review of the literature on self-awakening. Our aim is to i) contextualise the phenomenon, ii) propose an operating definition, and iii) summarise the scientific approaches used so far. The literature review identified 17 studies on self-awakening. Most of them adopted an objective sleep evaluation (76%), targeted nocturnal sleep (76%), and used a single criterion to define the success of awakening (82%); for most studies, this corresponded to awakening occurring in a time window of 30 minutes around the expected awakening time. Out of 715 total participants, 125 (17%) reported to be self-awakeners, with an average age of 23.24 years and a slight predominance of males compared to females. These results reveal self-awakening as a relatively rare phenomenon. To facilitate the study of self-awakening, and based on the results of the literature review, we propose a quick paper-and-pencil screening questionnaire for self-awakeners and provide an initial validation for it. Taken together, the combined results of the literature review and the proposed questionnaire help in characterising a theoretical framework for self-awakenings, while providing a useful tool and empirical suggestions for future experimental studies, which should ideally employ objective measurements.
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Affiliation(s)
- Laura Verga
- Research Group Comparative Bioacoustics, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
- Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Giada D'Este
- Department of Clinical Neurosciences and Department of Neurology, Sleep Disorders Center, San Raffaele Scientific Institute, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Sara Cassani
- Department of Clinical Neurosciences and Department of Neurology, Sleep Disorders Center, San Raffaele Scientific Institute, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Caterina Leitner
- Department of Clinical Neurosciences and Department of Neurology, Sleep Disorders Center, San Raffaele Scientific Institute, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Sonja A Kotz
- Department of Neuropsychology and Psychopharmacology, Maastricht University, Maastricht, The Netherlands
| | - Luigi Ferini-Strambi
- Department of Clinical Neurosciences and Department of Neurology, Sleep Disorders Center, San Raffaele Scientific Institute, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
| | - Andrea Galbiati
- Department of Clinical Neurosciences and Department of Neurology, Sleep Disorders Center, San Raffaele Scientific Institute, Milan, Italy
- Faculty of Psychology, Vita-Salute San Raffaele University, Milan, Italy
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7
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Neural complexity is a common denominator of human consciousness across diverse regimes of cortical dynamics. Commun Biol 2022; 5:1374. [PMID: 36522453 PMCID: PMC9755290 DOI: 10.1038/s42003-022-04331-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
What is the common denominator of consciousness across divergent regimes of cortical dynamics? Does consciousness show itself in decibels or in bits? To address these questions, we introduce a testbed for evaluating electroencephalogram (EEG) biomarkers of consciousness using dissociations between neural oscillations and consciousness caused by rare genetic disorders. Children with Angelman syndrome (AS) exhibit sleep-like neural dynamics during wakefulness. Conversely, children with duplication 15q11.2-13.1 syndrome (Dup15q) exhibit wake-like neural dynamics during non-rapid eye movement (NREM) sleep. To identify highly generalizable biomarkers of consciousness, we trained regularized logistic regression classifiers on EEG data from wakefulness and NREM sleep in children with AS using both entropy measures of neural complexity and spectral (i.e., neural oscillatory) EEG features. For each set of features, we then validated these classifiers using EEG from neurotypical (NT) children and abnormal EEGs from children with Dup15q. Our results show that the classification performance of entropy-based EEG biomarkers of conscious state is not upper-bounded by that of spectral EEG features, which are outperformed by entropy features. Entropy-based biomarkers of consciousness may thus be highly adaptable and should be investigated further in situations where spectral EEG features have shown limited success, such as detecting covert consciousness or anesthesia awareness.
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8
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Sevenius Nilsen A, Juel BE, Thürer B, Aamodt A, Storm JF. Are we really unconscious in "unconscious" states? Common assumptions revisited. Front Hum Neurosci 2022; 16:987051. [PMID: 36277049 PMCID: PMC9581328 DOI: 10.3389/fnhum.2022.987051] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/08/2022] [Indexed: 12/05/2022] Open
Abstract
In the field of consciousness science, there is a tradition to categorize certain states such as slow-wave non-REM sleep and deep general anesthesia as "unconscious". While this categorization seems reasonable at first glance, careful investigations have revealed that it is not so simple. Given that (1) behavioral signs of (un-)consciousness can be unreliable, (2) subjective reports of (un-)consciousness can be unreliable, and, (3) states presumed to be unconscious are not always devoid of reported experience, there are reasons to reexamine our traditional assumptions about "states of unconsciousness". While these issues are not novel, and may be partly semantic, they have implications both for scientific progress and clinical practice. We suggest that focusing on approaches that provide a more pragmatic and nuanced characterization of different experimental conditions may promote clarity in the field going forward, and help us build stronger foundations for future studies.
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Affiliation(s)
- Andre Sevenius Nilsen
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
| | - Bjørn E. Juel
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
- School of Medicine and Public Health, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison, Madison, WI, United States
| | - Benjamin Thürer
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
| | - Arnfinn Aamodt
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
| | - Johan F. Storm
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
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9
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Arena A, Juel BE, Comolatti R, Thon S, Storm JF. Capacity for consciousness under ketamine anaesthesia is selectively associated with activity in posteromedial cortex in rats. Neurosci Conscious 2022; 2022:niac004. [PMID: 35261778 PMCID: PMC8896332 DOI: 10.1093/nc/niac004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 12/09/2021] [Accepted: 01/24/2022] [Indexed: 12/04/2022] Open
Abstract
It remains unclear how specific cortical regions contribute to the brain's overall capacity for consciousness. Clarifying this could help distinguish between theories of consciousness. Here, we investigate the association between markers of regionally specific (de)activation and the brain's overall capacity for consciousness. We recorded electroencephalographic responses to cortical electrical stimulation in six rats and computed Perturbational Complexity Index state-transition (PCIST), which has been extensively validated as an index of the capacity for consciousness in humans. We also estimated the balance between activation and inhibition of specific cortical areas with the ratio between high and low frequency power from spontaneous electroencephalographic activity at each electrode. We repeated these measurements during wakefulness, and during two levels of ketamine anaesthesia: with the minimal dose needed to induce behavioural unresponsiveness and twice this dose. We found that PCIST was only slightly reduced from wakefulness to light ketamine anaesthesia, but dropped significantly with deeper anaesthesia. The high-dose effect was selectively associated with reduced high frequency/low frequency ratio in the posteromedial cortex, which strongly correlated with PCIST. Conversely, behavioural unresponsiveness induced by light ketamine anaesthesia was associated with similar spectral changes in frontal, but not posterior cortical regions. Thus, activity in the posteromedial cortex correlates with the capacity for consciousness, as assessed by PCIST, during different depths of ketamine anaesthesia, in rats, independently of behaviour. These results are discussed in relation to different theories of consciousness.
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Affiliation(s)
- A Arena
- Brain Signalling Group, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, Oslo 0372, Norway
| | - B E Juel
- Brain Signalling Group, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, Oslo 0372, Norway
- Center for Sleep and Consciousness, University of Wisconsin, 6001 Research Park Blvd, Madison, WI 53719, USA
| | - R Comolatti
- Department of Biomedical and Clinical Sciences “L. Sacco”, University of Milan, Via Giovanni Battista Grassi 74, Milano 20157, Italy
| | - S Thon
- Brain Signalling Group, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, Oslo 0372, Norway
| | - J F Storm
- Brain Signalling Group, Department of Molecular Medicine, University of Oslo, Sognsvannsveien 9, Oslo 0372, Norway
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10
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Sleep: Feeling awake while asleep. Curr Biol 2021; 31:R1578-R1580. [PMID: 34932967 DOI: 10.1016/j.cub.2021.10.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
What makes a good night's sleep? It is often assumed that sleep is the deepest when brain activity is dominated by hyper-synchronized slow waves. However, sleep appears subjectively the deepest in rapid eye movement (REM) sleep, when slow waves are absent.
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11
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Characterization of the Functional Dynamics in the Neonatal Brain during REM and NREM Sleep States by means of Microstate Analysis. Brain Topogr 2021; 34:555-567. [PMID: 34258668 PMCID: PMC8384814 DOI: 10.1007/s10548-021-00861-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 06/18/2021] [Indexed: 01/04/2023]
Abstract
Neonates spend most of their life sleeping. During sleep, their brain experiences fast changes in its functional organization. Microstate analysis permits to capture the rapid dynamical changes occurring in the functional organization of the brain by representing the changing spatio-temporal features of the electroencephalogram (EEG) as a sequence of short-lasting scalp topographies—the microstates. In this study, we modeled the ongoing neonatal EEG into sequences of a limited number of microstates and investigated whether the extracted microstate features are altered in REM and NREM sleep (usually known as active and quiet sleep states—AS and QS—in the newborn) and depend on the EEG frequency band. 19-channel EEG recordings from 60 full-term healthy infants were analyzed using a modified version of the k-means clustering algorithm. The results show that ~ 70% of the variance in the datasets can be described using 7 dominant microstate templates. The mean duration and mean occurrence of the dominant microstates were significantly different in the two sleep states. Microstate syntax analysis demonstrated that the microstate sequences characterizing AS and QS had specific non-casual structures that differed in the two sleep states. Microstate analysis of the neonatal EEG in specific frequency bands showed a clear dependence of the explained variance on frequency. Overall, our findings demonstrate that (1) the spatio-temporal dynamics of the neonatal EEG can be described by non-casual sequences of a limited number of microstate templates; (2) the brain dynamics described by these microstate templates depends on frequency; (3) the features of the microstate sequences can well differentiate the physiological conditions characterizing AS and QS.
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12
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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: 55] [Impact Index Per Article: 18.3] [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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13
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Imperatori LS, Cataldi J, Betta M, Ricciardi E, Ince RAA, Siclari F, Bernardi G. Cross-participant prediction of vigilance stages through the combined use of wPLI and wSMI EEG functional connectivity metrics. Sleep 2021; 44:5998102. [PMID: 33220055 DOI: 10.1093/sleep/zsaa247] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 11/01/2020] [Indexed: 11/12/2022] Open
Abstract
Functional connectivity (FC) metrics describe brain inter-regional interactions and may complement information provided by common power-based analyses. Here, we investigated whether the FC-metrics weighted Phase Lag Index (wPLI) and weighted Symbolic Mutual Information (wSMI) may unveil functional differences across four stages of vigilance-wakefulness (W), NREM-N2, NREM-N3, and REM sleep-with respect to each other and to power-based features. Moreover, we explored their possible contribution in identifying differences between stages characterized by distinct levels of consciousness (REM+W vs. N2+N3) or sensory disconnection (REM vs. W). Overnight sleep and resting-state wakefulness recordings from 24 healthy participants (27 ± 6 years, 13F) were analyzed to extract power and FC-based features in six classical frequency bands. Cross-validated linear discriminant analyses (LDA) were applied to investigate the ability of extracted features to discriminate (1) the four vigilance stages, (2) W+REM vs. N2+N3, and (3) W vs. REM. For the four-way vigilance stages classification, combining features based on power and both connectivity metrics significantly increased accuracy relative to considering only power, wPLI, or wSMI features. Delta-power and connectivity (0.5-4 Hz) represented the most relevant features for all the tested classifications, in line with a possible involvement of slow waves in consciousness and sensory disconnection. Sigma-FC, but not sigma-power (12-16 Hz), was found to strongly contribute to the differentiation between states characterized by higher (W+REM) and lower (N2+N3) probabilities of conscious experiences. Finally, alpha-FC resulted as the most relevant FC-feature for distinguishing among wakefulness and REM sleep and may thus reflect the level of disconnection from the external environment.
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Affiliation(s)
- Laura Sophie Imperatori
- MoMiLab, IMT School for Advanced Studies Lucca, Lucca, Italy.,Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Jacinthe Cataldi
- Center for Investigation and Research on Sleep, Lausanne University Hospital, Lausanne, Switzerland
| | - Monica Betta
- MoMiLab, IMT School for Advanced Studies Lucca, Lucca, Italy
| | | | - Robin A A Ince
- Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Francesca Siclari
- Center for Investigation and Research on Sleep, Lausanne University Hospital, Lausanne, Switzerland
| | - Giulio Bernardi
- MoMiLab, IMT School for Advanced Studies Lucca, Lucca, Italy.,Center for Investigation and Research on Sleep, Lausanne University Hospital, Lausanne, Switzerland
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14
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Daneault V, Orban P, Martin N, Dansereau C, Godbout J, Pouliot P, Dickinson P, Gosselin N, Vandewalle G, Maquet P, Lina JM, Doyon J, Bellec P, Carrier J. Cerebral functional networks during sleep in young and older individuals. Sci Rep 2021; 11:4905. [PMID: 33649377 PMCID: PMC7921592 DOI: 10.1038/s41598-021-84417-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2020] [Accepted: 02/15/2021] [Indexed: 11/09/2022] Open
Abstract
Even though sleep modification is a hallmark of the aging process, age-related changes in functional connectivity using functional Magnetic Resonance Imaging (fMRI) during sleep, remain unknown. Here, we combined electroencephalography and fMRI to examine functional connectivity differences between wakefulness and light sleep stages (N1 and N2 stages) in 16 young (23.1 ± 3.3y; 7 women), and 14 older individuals (59.6 ± 5.7y; 8 women). Results revealed extended, distributed (inter-between) and local (intra-within) decreases in network connectivity during sleep both in young and older individuals. However, compared to the young participants, older individuals showed lower decreases in connectivity or even increases in connectivity between thalamus/basal ganglia and several cerebral regions as well as between frontal regions of various networks. These findings reflect a reduced ability of the older brain to disconnect during sleep that may impede optimal disengagement for loss of responsiveness, enhanced lighter and fragmented sleep, and contribute to age effects on sleep-dependent brain plasticity.
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Affiliation(s)
- Véronique Daneault
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada.,Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Boulevard West, Montreal, QC, H4J 1C5, Canada.,Department of Psychology, University of Montreal, Downtown Station, P.O. Box 6128, Montreal, QC, H3C 3J7, Canada
| | - Pierre Orban
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada.,Department of Psychiatry, University of Montreal, Downtown Station, P.O. Box 6128, Montreal, QC, H3C 3J7, Canada.,Centre de Recherche de l'Institut Universitaire en Santé Mentale de Montréal, 7331 Hochelaga, Montreal, QC, H1N 3V2, Canada
| | - Nicolas Martin
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada.,Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Boulevard West, Montreal, QC, H4J 1C5, Canada.,Department of Psychology, University of Montreal, Downtown Station, P.O. Box 6128, Montreal, QC, H3C 3J7, Canada
| | - Christian Dansereau
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada
| | - Jonathan Godbout
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Boulevard West, Montreal, QC, H4J 1C5, Canada.,Génie Électrique, École de technologie supérieure, 1100, rue Notre-Dame Ouest, Montreal, QC, H3C 1K3, Canada
| | - Philippe Pouliot
- École Polytechnique de Montréal, Succursale Centre-Ville, C.P. 6079, Montreal, QC, H3C 3A7, Canada
| | - Philip Dickinson
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada
| | - Nadia Gosselin
- Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Boulevard West, Montreal, QC, H4J 1C5, Canada.,Department of Psychology, University of Montreal, Downtown Station, P.O. Box 6128, Montreal, QC, H3C 3J7, Canada
| | - Gilles Vandewalle
- GIGA-Cyclotron Research Centre-In Vivo Imaging, Université de Liège, Allée du 6 Août, Bâtiment B30, Sart Tilman, 4000, Liège, Belgium
| | - Pierre Maquet
- GIGA-Cyclotron Research Centre-In Vivo Imaging, Université de Liège, Allée du 6 Août, Bâtiment B30, Sart Tilman, 4000, Liège, Belgium
| | - Jean-Marc Lina
- Génie Électrique, École de technologie supérieure, 1100, rue Notre-Dame Ouest, Montreal, QC, H3C 1K3, Canada.,Centre de Recherches Mathématiques (CRM), Université de Montréal, Succursale Centre-Ville, Case postale 6128, Montreal, QC, H3C 3J7, Canada.,Biomedical Engineering Department, McGill University, 3775 University Street, Montreal, QC, H3A 2B4, Canada.,U678 INSERM, Paris, France
| | - Julien Doyon
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada
| | - Pierre Bellec
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada
| | - Julie Carrier
- Functional Neuroimaging Unit, University of Montreal Geriatric Institute, 4565, Queen-Mary Road, Montreal, QC, H3W 1W5, Canada. .,Center for Advanced Research in Sleep Medicine (CARSM), Hôpital du Sacré-Cœur de Montréal, 5400 Gouin Boulevard West, Montreal, QC, H4J 1C5, Canada. .,Department of Psychology, University of Montreal, Downtown Station, P.O. Box 6128, Montreal, QC, H3C 3J7, Canada.
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15
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Scarpelli S, Alfonsi V, Gorgoni M, Giannini AM, De Gennaro L. Investigation on Neurobiological Mechanisms of Dreaming in the New Decade. Brain Sci 2021; 11:brainsci11020220. [PMID: 33670180 PMCID: PMC7916906 DOI: 10.3390/brainsci11020220] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 02/05/2023] Open
Abstract
Dream research has advanced significantly over the last twenty years, thanks to the new applications of neuroimaging and electrophysiological techniques. Many findings pointed out that mental activity during sleep and wakefulness shared similar neural bases. On the other side, recent studies have highlighted that dream experience is promoted by significant brain activation, characterized by reduced low frequencies and increased rapid frequencies. Additionally, several studies confirmed that the posterior parietal area and prefrontal cortex are responsible for dream experience. Further, early results revealed that dreaming might be manipulated by sensory stimulations that would provoke the incorporation of specific cues into the dream scenario. Recently, transcranial stimulation techniques have been applied to modulate the level of consciousness during sleep, supporting previous findings and adding new information about neural correlates of dream recall. Overall, although multiple studies suggest that both the continuity and activation hypotheses provide a growing understanding of neural processes underlying dreaming, several issues are still unsolved. The impact of state-/trait-like variables, the influence of circadian and homeostatic factors, and the examination of parasomnia-like events to access dream contents are all opened issues deserving further deepening in future research.
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Affiliation(s)
- Serena Scarpelli
- Body and Action Lab, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy; (V.A.); (L.D.G.)
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (M.G.); (A.M.G.)
- Correspondence: ; Tel.: +39-06-4991-7508
| | - Valentina Alfonsi
- Body and Action Lab, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy; (V.A.); (L.D.G.)
| | - Maurizio Gorgoni
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (M.G.); (A.M.G.)
| | - Anna Maria Giannini
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (M.G.); (A.M.G.)
| | - Luigi De Gennaro
- Body and Action Lab, IRCCS Fondazione Santa Lucia, 00179 Rome, Italy; (V.A.); (L.D.G.)
- Department of Psychology, Sapienza University of Rome, 00185 Rome, Italy; (M.G.); (A.M.G.)
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16
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Abstract
Neuroplasticity is an area of expanding interest in psychiatry. Plasticity and metaplasticity are processes contributing to the scaling up and down of neuronal connections, and they are involved with changes in learning, memory, mood, and sleep. Effective mood treatments, including repetitive transcranial magnetic stimulation (rTMS), are reputed to work via changes in neuronal circuitry. This article explores the interrelatedness of sleep, plasticity, and rTMS treatment. A PubMed-based literature review was conducted to identify all available studies examining the relationship of rTMS, plasticity, and sleep. Key words used in this search included "TMS," "transcranial magnetic stimulation," "plasticity," "metaplasticity," "sleep," and "insomnia." Depressed mood tends to be associated with impaired neural plasticity, while antidepressant treatments can augment neural plasticity. rTMS impacts plasticity, yielding long-lasting effects, with differing impacts on the waking and sleeping brain. Higher quality sleep promotes plasticity and learning. Reports on the sleep impact of high-frequency and low-frequency rTMS are mixed. The efficacy of rTMS may rely on brain plasticity manipulation, enhanced via the stimulation of neural circuits. Total sleep time and sleep continuity are sleep qualities that are likely necessary but insufficient for the homeostatic plasticity driven by slow-wave sleep. Understanding the relationship between sleep and rTMS treatment is likely critical to enhancing outcomes.
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17
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Górska U, Rupp A, Celikel T, Englitz B. Assessing the state of consciousness for individual patients using complex, statistical stimuli. NEUROIMAGE-CLINICAL 2020; 29:102471. [PMID: 33388561 PMCID: PMC7788231 DOI: 10.1016/j.nicl.2020.102471] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 09/29/2020] [Accepted: 10/14/2020] [Indexed: 12/01/2022]
Abstract
Patients with prolonged disorders of consciousness (PDOC) are often unable to communicate their state of consciousness. Determining the latter is essential for the patient's care and prospects of recovery. Auditory stimulation in combination with neural recordings is a promising technique towards an objective assessment of conscious awareness. Here, we investigated the potential of complex, acoustic stimuli to elicit EEG responses suitable for classifying multiple subject groups, from unconscious to responding. We presented naturalistic auditory textures with unexpectedly changing statistics to human listeners. Awake, active listeners were asked to indicate the change by button press, while all other groups (awake passive, asleep, minimally conscious state (MCS), and unresponsive wakefulness syndrome (UWS)) listened passively. We quantified the evoked potential at stimulus onset and change in stimulus statistics, as well as the complexity of neural response during the change of stimulus statistics. On the group level, onset and change potentials classified patients and healthy controls successfully but failed to differentiate between the UWS and MCS groups. Conversely, the Lempel-Ziv complexity of the scalp-level potential allowed reliable differentiation between UWS and MCS even for individual subjects, when compared with the clinical assessment aligned to the EEG measurements. The accuracy appears to improve further when taking the latest available clinical diagnosis into account. In summary, EEG signal complexity during onset and changes in complex acoustic stimuli provides an objective criterion for distinguishing states of consciousness in clinical patients. These results suggest EEG-recordings as a cost-effective tool to choose appropriate treatments for non-responsive PDOC patients.
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Affiliation(s)
- U Górska
- Computational Neuroscience Laboratory, Department of Neurophysiology, Donders Institute, Radboud University Nijmegen, The Netherlands; Psychophysiology Laboratory, Institute of Psychology, Jagiellonian University, Krakow, Poland; Smoluchowski Institute of Physics, Jagiellonian University, Krakow, Poland.
| | - A Rupp
- Section of Biomagnetism, Department of Neurology, University of Heidelberg, Heidelberg, Germany
| | - T Celikel
- Computational Neuroscience Laboratory, Department of Neurophysiology, Donders Institute, Radboud University Nijmegen, The Netherlands
| | - B Englitz
- Computational Neuroscience Laboratory, Department of Neurophysiology, Donders Institute, Radboud University Nijmegen, The Netherlands.
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18
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Noreika V, Kamke MR, Canales-Johnson A, Chennu S, Bekinschtein TA, Mattingley JB. Alertness fluctuations when performing a task modulate cortical evoked responses to transcranial magnetic stimulation. Neuroimage 2020; 223:117305. [PMID: 32861789 PMCID: PMC7762840 DOI: 10.1016/j.neuroimage.2020.117305] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 07/31/2020] [Accepted: 08/21/2020] [Indexed: 12/21/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) has been widely used in human cognitive neuroscience to examine the causal role of distinct cortical areas in perceptual, cognitive and motor functions. However, it is widely acknowledged that the effects of focal cortical stimulation can vary substantially between participants and even from trial to trial within individuals. Recent work from resting state functional magnetic resonance imaging (fMRI) studies has suggested that spontaneous fluctuations in alertness over a testing session can modulate the neural dynamics of cortical processing, even when participants remain awake and responsive to the task at hand. Here we investigated the extent to which spontaneous fluctuations in alertness during wake-to-sleep transition can account for the variability in neurophysiological responses to TMS. We combined single-pulse TMS with neural recording via electroencephalography (EEG) to quantify changes in motor and cortical reactivity with fluctuating levels of alertness defined objectively on the basis of ongoing brain activity. We observed rapid, non-linear changes in TMS-evoked responses with decreasing levels of alertness, even while participants remained responsive in the behavioural task. Specifically, we found that the amplitude of motor evoked potentials peaked during periods of EEG flattening, whereas TMS-evoked potentials increased and remained stable during EEG flattening and the subsequent occurrence of theta ripples that indicate the onset of NREM stage 1 sleep. Our findings suggest a rapid and complex reorganization of active neural networks in response to spontaneous fluctuations of alertness over relatively short periods of behavioural testing during wake-to-sleep transition.
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Affiliation(s)
- Valdas Noreika
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072, Australia; Cambridge Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom; Department of Biological and Experimental Psychology, School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
| | - Marc R Kamke
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072, Australia
| | - Andrés Canales-Johnson
- Cambridge Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom; Vicerrectoría de Investigación y Posgrado, Universidad Católica del Maule, Talca, Chile
| | - Srivas Chennu
- School of Computing, University of Kent, Medway, United Kingdom; Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Tristan A Bekinschtein
- Cambridge Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, Cambridge CB2 3EB, United Kingdom
| | - Jason B Mattingley
- Queensland Brain Institute, University of Queensland, St Lucia, QLD 4072, Australia; School of Psychology, University of Queensland, St Lucia, QLD 4072, Australia; Canadian Institute for Advanced Research (CIFAR), Canada
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19
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Andrillon T, Kouider S. The vigilant sleeper: neural mechanisms of sensory (de)coupling during sleep. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2019.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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20
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Sterpenich V, Perogamvros L, Tononi G, Schwartz S. Fear in dreams and in wakefulness: Evidence for day/night affective homeostasis. Hum Brain Mapp 2019; 41:840-850. [PMID: 31663236 PMCID: PMC7267911 DOI: 10.1002/hbm.24843] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 10/04/2019] [Accepted: 10/15/2019] [Indexed: 12/14/2022] Open
Abstract
Recent neuroscientific theories have proposed that emotions experienced in dreams contribute to the resolution of emotional distress and preparation for future affective reactions. We addressed one emerging prediction, namely that experiencing fear in dreams is associated with more adapted responses to threatening signals during wakefulness. Using a stepwise approach across two studies, we identified brain regions activated when experiencing fear in dreams and showed that frightening dreams modulated the response of these same regions to threatening stimuli during wakefulness. Specifically, in Study 1, we performed serial awakenings in 18 participants recorded throughout the night with high‐density electroencephalography (EEG) and asked them whether they experienced any fear in their dreams. Insula and midcingulate cortex activity increased for dreams containing fear. In Study 2, we tested 89 participants and found that those reporting higher incidence of fear in their dreams showed reduced emotional arousal and fMRI response to fear‐eliciting stimuli in the insula, amygdala and midcingulate cortex, while awake. Consistent with better emotion regulation processes, the same participants displayed increased medial prefrontal cortex activity. These findings support that emotions in dreams and wakefulness engage similar neural substrates, and substantiate a link between emotional processes occurring during sleep and emotional brain functions during wakefulness.
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Affiliation(s)
- Virginie Sterpenich
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland
| | - Lampros Perogamvros
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland.,Center for Sleep Medicine, Division of Pulmonology, Department of Medicine, Geneva University Hospitals, Geneva, Switzerland.,Wisconsin Institute for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin - Madison, Madison, Wisconsin
| | - Giulio Tononi
- Wisconsin Institute for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin - Madison, Madison, Wisconsin
| | - Sophie Schwartz
- Department of Basic Neurosciences, Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Swiss Center for Affective Sciences, University of Geneva, Geneva, Switzerland
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21
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Andrillon T, Windt J, Silk T, Drummond SPA, Bellgrove MA, Tsuchiya N. Does the Mind Wander When the Brain Takes a Break? Local Sleep in Wakefulness, Attentional Lapses and Mind-Wandering. Front Neurosci 2019; 13:949. [PMID: 31572112 PMCID: PMC6753166 DOI: 10.3389/fnins.2019.00949] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 08/22/2019] [Indexed: 01/18/2023] Open
Abstract
Sleep has been classically described as an all-or-nothing global phenomenon. However, recent research strongly suggests that this view requires tempering. Invasive and non-invasive recordings in animals and humans show that neural activity typically associated with sleep can locally occur during wakefulness. Although local sleep is defined neuronally, it has been associated with impaired performance during cognitive tasks. Comparatively, the phenomenology of local sleep (i.e., what it feels like when your brain is partially asleep) has been less explored. Taking into account the literature on the neuronal and behavioral profile of local sleep intrusions in wakefulness, we propose that occurrences of local sleep could represent the neural mechanism underlying many attentional lapses. In particular, we argue that a unique physiological event such as local sleep could account for a diversity of behavioral outcomes from sluggish to impulsive responses. We further propose that local sleep intrusions could impact individuals' subjective experience. Specifically, we propose that the timing and anatomical sources of local sleep intrusions could be responsible for both the behavioral consequences and subjective content of attentional lapses and may underlie the difference between subjective experiences such as mind wandering and mind blanking. Our framework aims to build a parallel between spontaneous experiences in sleep and wakefulness by integrating evidence across neuronal, behavioral and experiential levels. We use the example of attention deficit hyperactivity disorder (ADHD) to illustrate how local sleep could explain complex cognitive profiles which include inattention, impulsivity, mind-wandering and mind-blanking.
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Affiliation(s)
- Thomas Andrillon
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Jennifer Windt
- School of Philosophical, Historical and International Studies, Monash University, Melbourne, VIC, Australia
| | - Tim Silk
- School of Psychology, Deakin University, Melbourne, VIC, Australia
- Murdoch Children’s Research Institute, Melbourne, VIC, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, VIC, Australia
| | - Sean P. A. Drummond
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, Monash University, Melbourne, VIC, Australia
| | - Mark A. Bellgrove
- School of Psychological Sciences, Turner Institute for Brain and Mental Health, 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), Osaka, Japan
- Advanced Telecommunications Research Computational Neuroscience Laboratories, Kyoto, Japan
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22
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Górska U, Binder M. Low- and medium-rate auditory steady-state responses in patients with prolonged disorders of consciousness correlate with Coma Recovery Scale - Revised score. Int J Psychophysiol 2019; 144:56-62. [PMID: 31381936 DOI: 10.1016/j.ijpsycho.2019.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 07/30/2019] [Accepted: 08/01/2019] [Indexed: 02/02/2023]
Abstract
Diagnosis of consciousness in patients with prolonged disorders of consciousness (PDOC) remains challenging since their responsiveness is often very impaired, while their assessment depends on observable behavior. The aim of this proof-of-concept study was to evaluate whether low- and medium-rate amplitude-modulated (AM) auditory steady-state responses (ASSRs) can be sensitive to the state of PDOC patients and may thus serve as a diagnostic tool which does not explicitly depend on a patient's cooperation. EEG was recorded from nine unresponsive wakefulness syndrome/vegetative state (UWS/VS) and eight minimally conscious state (MCS)/emergence from MCS patients during stimulation with two-minute trains of simple tones, amplitude modulated (AM) by 4 Hz, 6 Hz, 8 Hz, 12 Hz, 20 Hz, 40 Hz. The obtained ASSRs were then related to the Coma Recovery Scale - Revised (CRS-R) diagnosis and its total score. We observed significant correlations between mean inter-trial phase coherence (PC) (averaged across all stimulation frequencies) and total CRS-R score, as well as between 40 Hz relative power (RP) and total CRS-R score. Moreover, both parameters significantly differed between the patient groups. Our preliminary results suggest that a passive auditory stimulation protocol consisting of low- and medium-rate ASSRs might be used as an objective estimate of the level of neural dysfunction in PDOC patients. Consequently, the integrity of the auditory system appears to be an important predictor of the actual state of consciousness in PDOC patients.
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Affiliation(s)
- Urszula Górska
- Psychophysiology Laboratory, Institute of Psychology, Jagiellonian University, Krakow, Poland; Department of Neurophysiology, Donders Centre for Neuroscience, Radboud University Nijmegen, the Netherlands
| | - Marek Binder
- Psychophysiology Laboratory, Institute of Psychology, Jagiellonian University, Krakow, Poland.
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23
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Lamme VAF. Challenges for theories of consciousness: seeing or knowing, the missing ingredient and how to deal with panpsychism. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0344. [PMID: 30061458 DOI: 10.1098/rstb.2017.0344] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2018] [Indexed: 12/24/2022] Open
Abstract
Significant progress has been made in the study of consciousness. Promising theories have been developed and a wealth of experimental data has been generated, both guiding us towards a better understanding of this complex phenomenon. However, new challenges have surfaced. Is visual consciousness about the seeing or the knowing that you see? Controversy about whether the conscious experience is better explained by theories that focus on phenomenal (P-consciousness) or cognitive aspects (A-consciousness) remains, and the debate seems to reach a stalemate. Can we ever resolve this? A further challenge is that many theories of consciousness seem to endorse high degrees of panpsychism-the notion that all beings or even lifeless objects have conscious experience. Should we accept this, or does it imply that these theories require further ingredients that would put a lower bound on beings or devices that have conscious experience? If so, what could these 'missing ingredients' be? These challenges are discussed, and potential solutions are offered.This article is part of the theme issue 'Perceptual consciousness and cognitive access'.
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Affiliation(s)
- Victor A F Lamme
- Amsterdam Brain and Cognition (ABC), Department of Psychology, University of Amsterdam, 1001 NK Amsterdam, The Netherlands
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24
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Baird B, Mota-Rolim SA, Dresler M. The cognitive neuroscience of lucid dreaming. Neurosci Biobehav Rev 2019; 100:305-323. [PMID: 30880167 PMCID: PMC6451677 DOI: 10.1016/j.neubiorev.2019.03.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 03/06/2019] [Accepted: 03/11/2019] [Indexed: 12/17/2022]
Abstract
Lucid dreaming refers to the phenomenon of becoming aware of the fact that one is dreaming during ongoing sleep. Despite having been physiologically validated for decades, the neurobiology of lucid dreaming is still incompletely characterized. Here we review the neuroscientific literature on lucid dreaming, including electroencephalographic, neuroimaging, brain lesion, pharmacological and brain stimulation studies. Electroencephalographic studies of lucid dreaming are mostly underpowered and show mixed results. Neuroimaging data is scant but preliminary results suggest that prefrontal and parietal regions are involved in lucid dreaming. A focus of research is also to develop methods to induce lucid dreams. Combining training in mental set with cholinergic stimulation has shown promising results, while it remains unclear whether electrical brain stimulation could be used to induce lucid dreams. Finally, we discuss strategies to measure lucid dreaming, including best-practice procedures for the sleep laboratory. Lucid dreaming has clinical and scientific applications, and shows emerging potential as a methodology in the cognitive neuroscience of consciousness. Further research with larger sample sizes and refined methodology is needed.
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Affiliation(s)
- Benjamin Baird
- Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison, Madison, WI, USA.
| | - Sergio A Mota-Rolim
- Brain Institute, Physiology Department and Onofre Lopes University Hospital - Federal University of Rio Grande do Norte, Natal, Brazil
| | - Martin Dresler
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, the Netherlands
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25
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Legendre G, Andrillon T, Koroma M, Kouider S. Sleepers track informative speech in a multitalker environment. Nat Hum Behav 2019; 3:274-283. [DOI: 10.1038/s41562-018-0502-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 11/20/2018] [Indexed: 11/09/2022]
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26
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27
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Low and medium frequency auditory steady-state responses decrease during NREM sleep. Int J Psychophysiol 2018; 135:44-54. [PMID: 30452935 DOI: 10.1016/j.ijpsycho.2018.11.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 11/23/2022]
Abstract
Previous research on auditory steady-state responses (ASSRs) demonstrated sensitivity of 40 Hz ASSR to changes in the level of arousal, both in sleep and in general anaesthesia. In this study we extended the range of stimulation frequencies, using also low and medium stimulation frequencies (4, 6, 8, 12, 20, 40 Hz) and studied their susceptibility to the loss of consciousness in NREM sleep (N2 and N3 stages). Effects of NREM sleep were examined in power domain with relative power (RP), and in phase domain using inter-trial phase coherence (PC) parameter. The activity in power domain was also compared to no-stimulation data. Regions displaying significant waking-NREM sleep differences were selected using non-parametric suprathreshold cluster test. For 4, 6, 20 and 40 Hz stimulation relative power of ASSRs was lower in NREM sleep, with maximal change for 40 Hz stimulation. This decrease was not seen in no-stimulation condition. For all stimulation frequencies (except 12 Hz) we observed decrease of phase coherence of ASSR during NREM sleep. Our results demonstrate that low and medium frequency ASSRs are state-sensitive, thus susceptible to loss of consciousness during NREM sleep. Diminishing of power and phase coherence may result from cortical down states and/or thalamic inhibition. Our results support possible use of low- and medium-frequency ASSRs for discrimination between states of altered consciousness and emphasize the role of the auditory system in determining these variations.
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28
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Fernandez LMJ, Comte JC, Le Merre P, Lin JS, Salin PA, Crochet S. Highly Dynamic Spatiotemporal Organization of Low-Frequency Activities During Behavioral States in the Mouse Cerebral Cortex. Cereb Cortex 2018; 27:5444-5462. [PMID: 27742711 DOI: 10.1093/cercor/bhw311] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 09/19/2016] [Indexed: 12/13/2022] Open
Abstract
Although low-frequency (LF < 10 Hz) activities have been considered as a hallmark of nonrapid eye movement (NREM) sleep, several studies have recently reported LF activities in the membrane potential of cortical neurons from different areas in awake mice. However, little is known about the spatiotemporal organization of LF activities across cortical areas during wakefulness and to what extent it differs during NREM sleep. We have thus investigated the dynamics of LF activities across cortical areas in awake and sleeping mice using chronic simultaneous local field potential recordings. We found that LF activities had higher amplitude in somatosensory and motor areas during quiet wakefulness and decreased in most areas during active wakefulness, resulting in a global state change that was overall correlated with motor activity. However, we also observed transient desynchronization of cortical states between areas, indicating a more local state regulation. During NREM sleep, LF activities had higher amplitude in all areas but slow-wave activity was only poorly correlated across cortical areas. Despite a maximal amplitude during NREM sleep, the coherence of LF activities between areas that are not directly connected dropped from wakefulness to NREM sleep, potentially reflecting a breakdown of long-range cortical integration associated with loss of consciousness.
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Affiliation(s)
- Laura M J Fernandez
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Integrative Physiology of the Brain Arousal System Team, Lyon Cedex 08 F-69000, France.,Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France
| | - Jean-Christophe Comte
- Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France.,INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Forgetting and Cortical Dynamics Team, Lyon Cedex 08 F-69000, France.,INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Biphoton Microscopy, Lyon F-69000, France
| | - Pierre Le Merre
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Integrative Physiology of the Brain Arousal System Team, Lyon Cedex 08 F-69000, France.,Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France
| | - Jian-Sheng Lin
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Integrative Physiology of the Brain Arousal System Team, Lyon Cedex 08 F-69000, France.,Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France
| | - Paul-A Salin
- Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France.,INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Forgetting and Cortical Dynamics Team, Lyon Cedex 08 F-69000, France.,INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Biphoton Microscopy, Lyon F-69000, France
| | - Sylvain Crochet
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Integrative Physiology of the Brain Arousal System Team, Lyon Cedex 08 F-69000, France.,Lyon Neuroscience Research Center, University Lyon 1, Lyon Cedex 08 F-69000, France.,Laboratory of Sensory Processing, EPFL, Lausanne CH-1015, Switzerland
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29
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Mikulan E, Hesse E, Sedeño L, Bekinschtein T, Sigman M, García MDC, Silva W, Ciraolo C, García AM, Ibáñez A. Intracranial high-γ connectivity distinguishes wakefulness from sleep. Neuroimage 2017; 169:265-277. [PMID: 29225064 DOI: 10.1016/j.neuroimage.2017.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 11/21/2017] [Accepted: 12/06/2017] [Indexed: 12/27/2022] Open
Abstract
Neural synchrony in the γ-band is considered a fundamental process in cortical computation and communication and it has also been proposed as a crucial correlate of consciousness. However, the latter claim remains inconclusive, mainly due to methodological limitations, such as the spectral constraints of scalp-level electroencephalographic recordings or volume-conduction confounds. Here, we circumvented these caveats by comparing γ-band connectivity between two global states of consciousness via intracranial electroencephalography (iEEG), which provides the most reliable measurements of high-frequency activity in the human brain. Non-REM Sleep recordings were compared to passive-wakefulness recordings of the same duration in three subjects with surgically implanted electrodes. Signals were analyzed through the weighted Phase Lag Index connectivity measure and relevant graph theory metrics. We found that connectivity in the high-γ range (90-120 Hz), as well as relevant graph theory properties, were higher during wakefulness than during sleep and discriminated between conditions better than any other canonical frequency band. Our results constitute the first report of iEEG differences between wakefulness and sleep in the high-γ range at both local and distant sites, highlighting the utility of this technique in the search for the neural correlates of global states of consciousness.
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Affiliation(s)
- Ezequiel Mikulan
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, UK.
| | - Eugenia Hesse
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Instituto de Ingeniería Biomédica, Facultad de Ingeniería, Universidad de Buenos Aires, Argentina
| | - Lucas Sedeño
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina
| | - Tristán Bekinschtein
- Consciousness and Cognition Lab, Department of Psychology, University of Cambridge, UK
| | | | - María Del Carmen García
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Walter Silva
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Carlos Ciraolo
- Programa de Cirugía de Epilepsia, Hospital Italiano de Buenos Asires, Buenos Aires, Argentina
| | - Adolfo M García
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Faculty of Education, National University of Cuyo (UNCuyo), Mendoza, Argentina
| | - Agustín Ibáñez
- Laboratory of Experimental Psychology and Neuroscience (LPEN), Institute of Cognitive and Translational Neuroscience (INCYT), INECO Foundation, Favaloro University, Buenos Aires, Argentina; National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina; Universidad Autónoma del Caribe, Barranquilla, Colombia; Center for Social and Cognitive Neuroscience (CSCN), School of Psychology, Universidad Adolfo Ibañez, Santiago de Chile, Chile; Australian Research Council Centre of Excellence in Cognition and its Disorders, Sydney, Australia.
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30
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Lustenberger C, Patel YA, Alagapan S, Page JM, Price B, Boyle MR, Fröhlich F. High-density EEG characterization of brain responses to auditory rhythmic stimuli during wakefulness and NREM sleep. Neuroimage 2017; 169:57-68. [PMID: 29217404 DOI: 10.1016/j.neuroimage.2017.12.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 11/13/2017] [Accepted: 12/02/2017] [Indexed: 01/12/2023] Open
Abstract
Auditory rhythmic sensory stimulation modulates brain oscillations by increasing phase-locking to the temporal structure of the stimuli and by increasing the power of specific frequency bands, resulting in Auditory Steady State Responses (ASSR). The ASSR is altered in different diseases of the central nervous system such as schizophrenia. However, in order to use the ASSR as biological markers for disease states, it needs to be understood how different vigilance states and underlying brain activity affect the ASSR. Here, we compared the effects of auditory rhythmic stimuli on EEG brain activity during wake and NREM sleep, investigated the influence of the presence of dominant sleep rhythms on the ASSR, and delineated the topographical distribution of these modulations. Participants (14 healthy males, 20-33 years) completed on the same day a 60 min nap session and two 30 min wakefulness sessions (before and after the nap). During these sessions, amplitude modulated (AM) white noise auditory stimuli at different frequencies were applied. High-density EEG was continuously recorded and time-frequency analyses were performed to assess ASSR during wakefulness and NREM periods. Our analysis revealed that depending on the electrode location, stimulation frequency applied and window/frequencies analysed the ASSR was significantly modulated by sleep pressure (before and after sleep), vigilance state (wake vs. NREM sleep), and the presence of slow wave activity and sleep spindles. Furthermore, AM stimuli increased spindle activity during NREM sleep but not during wakefulness. Thus, (1) electrode location, sleep history, vigilance state and ongoing brain activity needs to be carefully considered when investigating ASSR and (2) auditory rhythmic stimuli during sleep might represent a powerful tool to boost sleep spindles.
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Affiliation(s)
- Caroline Lustenberger
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Yogi A Patel
- Bioengineering Graduate Program, Georgia Institute of Technology, Atlanta, GA 30332, USA; Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332, USA
| | - Sankaraleengam Alagapan
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jessica M Page
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Betsy Price
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Michael R Boyle
- Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA
| | - Flavio Fröhlich
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Department of Neurology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Carolina Center for Neurostimulation, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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31
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Lioi G, Bell SL, Smith DC, Simpson DM. Directional connectivity in the EEG is able to discriminate wakefulness from NREM sleep. Physiol Meas 2017; 38:1802-1820. [PMID: 28737503 DOI: 10.1088/1361-6579/aa81b5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A reliable measure of consciousness is of great interest for various clinical applications including sleep studies and the assessment of depth of anaesthesia. A number of measures of consciousness based on the EEG have been proposed in the literature and tested in studies of dreamless sleep, general anaesthesia and disorders of consciousness. However, reliability has remained a persistent challenge. Despite considerable theoretical and experimental effort, the neural mechanisms underlying consciousness remain unclear, but connectivity between brain regions is thought to be disrupted, impairing information flow. OBJECTIVE The objective of the current work was to assess directional connectivity between brain regions using directed coherence and propose and assess an index that robustly reflects changes associated with non-REM sleep. APPROACH We tested the performance on polysomnographic recordings from ten healthy subjects and compared directed coherence (and derived features) with more established measures calculated from EEG spectra. We compared the performance of the different indexes to discriminate the level of consciousness at group and individual level. MAIN RESULTS At a group level all EEG measures could significantly discriminate NREM sleep from waking, but there was considerable individual variation. Across all individuals, normalized power, the strength of long-range connections and the direction of functional links strongly correlate with NREM sleep stages over the experimental timeline. At an individual level, of the EEG measures considered, the direction of functional links constitutes the most reliable index of the level of consciousness, highly correlating with the individual experimental time-line of sleep in all subjects. SIGNIFICANCE Directed coherence provides a promising new means of assessing level of consciousness, firmly based on current physiological understanding of consciousness.
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Affiliation(s)
- G Lioi
- Institute for Sound and Vibration Research, University of Southampton, Southampton, United Kingdom
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32
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Stitt I, Hollensteiner KJ, Galindo-Leon E, Pieper F, Fiedler E, Stieglitz T, Engler G, Nolte G, Engel AK. Dynamic reconfiguration of cortical functional connectivity across brain states. Sci Rep 2017; 7:8797. [PMID: 28821753 PMCID: PMC5562766 DOI: 10.1038/s41598-017-08050-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 07/04/2017] [Indexed: 12/18/2022] Open
Abstract
Throughout each day, the brain displays transient changes in state, as evidenced by shifts in behavior and vigilance. While the electrophysiological correlates of brain states have been studied for some time, it remains unclear how large-scale cortico-cortical functional connectivity systematically reconfigures across states. Here, we investigate state-dependent shifts in cortical functional connectivity by recording local field potentials (LFPs) during spontaneous behavioral transitions in the ferret using chronically implanted micro-electrocorticographic (µECoG) arrays positioned over occipital, parietal, and temporal cortical regions. To objectively classify brain state, we describe a data-driven approach that projects time-varying LFP spectral properties into brain state space. Distinct brain states displayed markedly different patterns of cross-frequency phase-amplitude coupling and inter-electrode phase synchronization across several LFP frequency bands. The largest across-state differences in functional connectivity were observed between periods of presumed slow-wave and rapid-eye-movement-sleep/active-state, which were characterized by the contrasting phenomena of cortical network fragmentation and global synchronization, respectively. Collectively, our data provide strong evidence that large-scale functional interactions in the brain dynamically reconfigure across behavioral states.
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Affiliation(s)
- Iain Stitt
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany. .,Department of Psychiatry, Neuroscience Center, University of North Carolina, Chapel Hill, NC, 27514, USA.
| | - Karl J Hollensteiner
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Edgar Galindo-Leon
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Florian Pieper
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Eva Fiedler
- Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
| | - Thomas Stieglitz
- Department of Microsystems Engineering, University of Freiburg, 79110, Freiburg, Germany
| | - Gerhard Engler
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Guido Nolte
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Andreas K Engel
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
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33
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Neural Markers of Responsiveness to the Environment in Human Sleep. J Neurosci 2017; 36:6583-96. [PMID: 27307244 DOI: 10.1523/jneurosci.0902-16.2016] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/14/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Sleep is characterized by a loss of behavioral responsiveness. However, recent research has shown that the sleeping brain is not completely disconnected from its environment. How neural activity constrains the ability to process sensory information while asleep is yet unclear. Here, we instructed human volunteers to classify words with lateralized hand responses while falling asleep. Using an electroencephalographic (EEG) marker of motor preparation, we show how responsiveness is modulated across sleep. These modulations are tracked using classic event-related potential analyses complemented by Lempel-Ziv complexity (LZc), a measure shown to track arousal in sleep and anesthesia. Neural activity related to the semantic content of stimuli was conserved in light non-rapid eye movement (NREM) sleep. However, these processes were suppressed in deep NREM sleep and, importantly, also in REM sleep, despite the recovery of wake-like neural activity in the latter. In NREM sleep, sensory activations were counterbalanced by evoked down states, which, when present, blocked further processing of external information. In addition, responsiveness markers correlated positively with baseline complexity, which could be related to modulation in sleep depth. In REM sleep, however, this relationship was reversed. We therefore propose that, in REM sleep, endogenously generated processes compete with the processing of external input. Sleep can thus be seen as a self-regulated process in which external information can be processed in lighter stages but suppressed in deeper stages. Last, our results suggest drastically different gating mechanisms in NREM and REM sleep. SIGNIFICANCE STATEMENT Previous research has tempered the notion that sleepers are isolated from their environment. Here, we pushed this idea forward and examined, across all sleep stages, the brain's ability to flexibly process sensory information, up to the decision level. We extracted an EEG marker of motor preparation to determine the completion of the sensory processing chain and explored how it is constrained by baseline and evoked neural activity. In NREM sleep, slow waves elicited by stimuli appeared to block response preparation. We also used a novel analytic approach (Lempel-Ziv complexity) and showed that the ability to process external information correlates with neural complexity. A reversal of the correlation between complexity and motor indices in REM sleep suggests drastically different gating mechanisms across sleep stages.
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34
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Perogamvros L, Baird B, Seibold M, Riedner B, Boly M, Tononi G. The Phenomenal Contents and Neural Correlates of Spontaneous Thoughts across Wakefulness, NREM Sleep, and REM Sleep. J Cogn Neurosci 2017; 29:1766-1777. [PMID: 28562209 DOI: 10.1162/jocn_a_01155] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Thoughts occur during wake as well as during dreaming sleep. Using experience sampling combined with high-density EEG, we investigated the phenomenal qualities and neural correlates of spontaneously occurring thoughts across wakefulness, non-rapid eye movement (NREM) sleep, and REM sleep. Across all states, thoughts were associated with activation of a region of the midcingulate cortex. Thoughts during wakefulness additionally involved a medial prefrontal region, which was associated with metacognitive thoughts during wake. Phenomenologically, waking thoughts had more metacognitive content than thoughts during both NREM and REM sleep, whereas thoughts during REM sleep had a more social content. Together, these results point to a core neural substrate for thoughts, regardless of behavioral state, within the midcingulate cortex, and suggest that medial prefrontal regions may contribute to metacognitive content in waking thoughts.
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Affiliation(s)
- Lampros Perogamvros
- University of Wisconsin-Madison.,Geneva University Hospitals.,University of Geneva
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35
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Abstract
Consciousness never fades during wake. However, if awakened from sleep, sometimes we report dreams and sometimes no experiences. Traditionally, dreaming has been identified with REM sleep, characterized by a wake-like, globally ‘activated’, high-frequency EEG. However, dreaming also occurs in NREM sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density EEG, we contrasted the presence and absence of dreaming within NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with a local decrease in low-frequency activity in posterior cortical regions. High-frequency activity within these regions correlated with specific dream contents. Monitoring this posterior ‘hot zone’ predicted whether an individual reported dreaming or the absence of experiences during NREM sleep in real time, suggesting that it may constitute a core correlate of conscious experiences in sleep.
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36
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Spontaneous eyelid closures link vigilance fluctuation with fMRI dynamic connectivity states. Proc Natl Acad Sci U S A 2016; 113:9653-8. [PMID: 27512040 DOI: 10.1073/pnas.1523980113] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Fluctuations in resting-state functional connectivity occur but their behavioral significance remains unclear, largely because correlating behavioral state with dynamic functional connectivity states (DCS) engages probes that disrupt the very behavioral state we seek to observe. Observing spontaneous eyelid closures following sleep deprivation permits nonintrusive arousal monitoring. During periods of low arousal dominated by eyelid closures, sliding-window correlation analysis uncovered a DCS associated with reduced within-network functional connectivity of default mode and dorsal/ventral attention networks, as well as reduced anticorrelation between these networks. Conversely, during periods when participants' eyelids were wide open, a second DCS was associated with less decoupling between the visual network and higher-order cognitive networks that included dorsal/ventral attention and default mode networks. In subcortical structures, eyelid closures were associated with increased connectivity between the striatum and thalamus with the ventral attention network, and greater anticorrelation with the dorsal attention network. When applied to task-based fMRI data, these two DCS predicted interindividual differences in frequency of behavioral lapsing and intraindividual temporal fluctuations in response speed. These findings with participants who underwent a night of total sleep deprivation were replicated in an independent dataset involving partially sleep-deprived participants. Fluctuations in functional connectivity thus appear to be clearly associated with changes in arousal.
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37
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Nieminen JO, Gosseries O, Massimini M, Saad E, Sheldon AD, Boly M, Siclari F, Postle BR, Tononi G. Consciousness and cortical responsiveness: a within-state study during non-rapid eye movement sleep. Sci Rep 2016; 6:30932. [PMID: 27491799 PMCID: PMC4974655 DOI: 10.1038/srep30932] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/06/2016] [Indexed: 11/10/2022] Open
Abstract
When subjects become unconscious, there is a characteristic change in the way the cerebral cortex responds to perturbations, as can be assessed using transcranial magnetic stimulation and electroencephalography (TMS-EEG). For instance, compared to wakefulness, during non-rapid eye movement (NREM) sleep TMS elicits a larger positive-negative wave, fewer phase-locked oscillations, and an overall simpler response. However, many physiological variables also change when subjects go from wake to sleep, anesthesia, or coma. To avoid these confounding factors, we focused on NREM sleep only and measured TMS-evoked EEG responses before awakening the subjects and asking them if they had been conscious (dreaming) or not. As shown here, when subjects reported no conscious experience upon awakening, TMS evoked a larger negative deflection and a shorter phase-locked response compared to when they reported a dream. Moreover, the amplitude of the negative deflection-a hallmark of neuronal bistability according to intracranial studies-was inversely correlated with the length of the dream report (i.e., total word count). These findings suggest that variations in the level of consciousness within the same physiological state are associated with changes in the underlying bistability in cortical circuits.
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Affiliation(s)
- Jaakko O Nieminen
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland
| | - Olivia Gosseries
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Psychology, University of Wisconsin, Madison, WI, USA.,Coma Science Group, GIGA-Research &Neurology Department, University and University Hospital of Liege, Liege, Belgium
| | - Marcello Massimini
- Department of Clinical Sciences "Luigi Sacco", Università degli Studi di Milano, Milan, Italy.,Don C. Gnocchi Foundation IRCCS, Milan, Italy
| | - Elyana Saad
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Psychology, University of Wisconsin, Madison, WI, USA
| | - Andrew D Sheldon
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Psychology, University of Wisconsin, Madison, WI, USA
| | - Melanie Boly
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Neurology, University of Wisconsin, Madison, WI, USA
| | - Francesca Siclari
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Centre for Investigation and Research on Sleep, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Bradley R Postle
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA.,Department of Psychology, University of Wisconsin, Madison, WI, USA
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI, USA
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38
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Wilf M, Ramot M, Furman-Haran E, Arzi A, Levkovitz Y, Malach R. Diminished Auditory Responses during NREM Sleep Correlate with the Hierarchy of Language Processing. PLoS One 2016; 11:e0157143. [PMID: 27310812 PMCID: PMC4911044 DOI: 10.1371/journal.pone.0157143] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/25/2016] [Indexed: 11/18/2022] Open
Abstract
Natural sleep provides a powerful model system for studying the neuronal correlates of awareness and state changes in the human brain. To quantitatively map the nature of sleep-induced modulations in sensory responses we presented participants with auditory stimuli possessing different levels of linguistic complexity. Ten participants were scanned using functional magnetic resonance imaging (fMRI) during the waking state and after falling asleep. Sleep staging was based on heart rate measures validated independently on 20 participants using concurrent EEG and heart rate measurements and the results were confirmed using permutation analysis. Participants were exposed to three types of auditory stimuli: scrambled sounds, meaningless word sentences and comprehensible sentences. During non-rapid eye movement (NREM) sleep, we found diminishing brain activation along the hierarchy of language processing, more pronounced in higher processing regions. Specifically, the auditory thalamus showed similar activation levels during sleep and waking states, primary auditory cortex remained activated but showed a significant reduction in auditory responses during sleep, and the high order language-related representation in inferior frontal gyrus (IFG) cortex showed a complete abolishment of responses during NREM sleep. In addition to an overall activation decrease in language processing regions in superior temporal gyrus and IFG, those areas manifested a loss of semantic selectivity during NREM sleep. Our results suggest that the decreased awareness to linguistic auditory stimuli during NREM sleep is linked to diminished activity in high order processing stations.
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Affiliation(s)
- Meytal Wilf
- Department of Neurobiology, Weizmann Institute of Science, Rehreovot 76100, Israel
- * E-mail:
| | - Michal Ramot
- Department of Neurobiology, Weizmann Institute of Science, Rehreovot 76100, Israel
| | - Edna Furman-Haran
- Department of Biological Services, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Anat Arzi
- Department of Neurobiology, Weizmann Institute of Science, Rehreovot 76100, Israel
| | - Yechiel Levkovitz
- Shalvata Mental Health Care Center, School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Rafael Malach
- Department of Neurobiology, Weizmann Institute of Science, Rehreovot 76100, Israel
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39
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Hoel EP, Albantakis L, Cirelli C, Tononi G. Synaptic refinement during development and its effect on slow-wave activity: a computational study. J Neurophysiol 2016; 115:2199-213. [PMID: 26843602 DOI: 10.1152/jn.00812.2015] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 02/02/2016] [Indexed: 01/28/2023] Open
Abstract
Recent evidence suggests that synaptic refinement, the reorganization of synapses and connections without significant change in their number or strength, is important for the development of the visual system of juvenile rodents. Other evidence in rodents and humans shows that there is a marked drop in sleep slow-wave activity (SWA) during adolescence. Slow waves reflect synchronous transitions of neuronal populations between active and inactive states, and the amount of SWA is influenced by the connection strength and organization of cortical neurons. In this study, we investigated whether synaptic refinement could account for the observed developmental drop in SWA. To this end, we employed a large-scale neural model of primary visual cortex and sections of the thalamus, capable of producing realistic slow waves. In this model, we reorganized intralaminar connections according to experimental data on synaptic refinement: during prerefinement, local connections between neurons were homogenous, whereas in postrefinement, neurons connected preferentially to neurons with similar receptive fields and preferred orientations. Synaptic refinement led to a drop in SWA and to changes in slow-wave morphology, consistent with experimental data. To test whether learning can induce synaptic refinement, intralaminar connections were equipped with spike timing-dependent plasticity. Oriented stimuli were presented during a learning period, followed by homeostatic synaptic renormalization. This led to activity-dependent refinement accompanied again by a decline in SWA. Together, these modeling results show that synaptic refinement can account for developmental changes in SWA. Thus sleep SWA may be used to track noninvasively the reorganization of cortical connections during development.
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Affiliation(s)
- Erik P Hoel
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin; and Neuroscience Training Program, University of Wisconsin-Madison, Madison, Wisconsin
| | - Larissa Albantakis
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin; and
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40
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Plante DT, Goldstein MR, Cook JD, Smith R, Riedner BA, Rumble ME, Jelenchick L, Roth A, Tononi G, Benca RM, Peterson MJ. Effects of oral temazepam on slow waves during non-rapid eye movement sleep in healthy young adults: A high-density EEG investigation. Int J Psychophysiol 2016; 101:25-32. [PMID: 26779596 DOI: 10.1016/j.ijpsycho.2016.01.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/11/2016] [Accepted: 01/13/2016] [Indexed: 11/26/2022]
Abstract
Slow waves are characteristic waveforms that occur during non-rapid eye movement (NREM) sleep that play an integral role in sleep quality and brain plasticity. Benzodiazepines are commonly used medications that alter slow waves, however, their effects may depend on the time of night and measure used to characterize slow waves. Prior investigations have utilized minimal scalp derivations to evaluate the effects of benzodiazepines on slow waves, and thus the topography of changes to slow waves induced by benzodiazepines has yet to be fully elucidated. This study used high-density electroencephalography (hdEEG) to evaluate the effects of oral temazepam on slow wave activity, incidence, and morphology during NREM sleep in 18 healthy adults relative to placebo. Temazepam was associated with significant decreases in slow wave activity and incidence, which were most prominent in the latter portions of the sleep period. However, temazepam was also associated with a decrease in the magnitude of high-amplitude slow waves and their slopes in the first NREM sleep episode, which was most prominent in frontal derivations. These findings suggest that benzodiazepines produce changes in slow waves throughout the night that vary depending on cortical topography and measures used to characterize slow waves. Further research that explores the relationships between benzodiazepine-induced changes to slow waves and the functional effects of these waveforms is indicated.
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Affiliation(s)
- D T Plante
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA.
| | - M R Goldstein
- Department of Psychology, University of Arizona, Tucson, AZ, USA
| | - J D Cook
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - R Smith
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - B A Riedner
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - M E Rumble
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - L Jelenchick
- University of Minnesota Medical Scientist Training Program Minneapolis, MN, USA
| | - A Roth
- Ferkauf Graduate School of Psychology, Yeshiva University, New York, NY, USA
| | - G Tononi
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - R M Benca
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
| | - M J Peterson
- University of Wisconsin School of Medicine and Public Health, Department of Psychiatry, Madison, WI, USA
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41
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Hale JR, White TP, Mayhew SD, Wilson RS, Rollings DT, Khalsa S, Arvanitis TN, Bagshaw AP. Altered thalamocortical and intra-thalamic functional connectivity during light sleep compared with wake. Neuroimage 2015; 125:657-667. [PMID: 26499809 DOI: 10.1016/j.neuroimage.2015.10.041] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/16/2015] [Accepted: 10/16/2015] [Indexed: 01/14/2023] Open
Abstract
The transition from wakefulness into sleep is accompanied by modified activity in the brain's thalamocortical network. Sleep-related decreases in thalamocortical functional connectivity (FC) have previously been reported, but the extent to which these changes differ between thalamocortical pathways, and patterns of intra-thalamic FC during sleep remain untested. To non-invasively investigate thalamocortical and intra-thalamic FC as a function of sleep stage we recorded simultaneous EEG-fMRI data in 13 healthy participants during their descent into light sleep. Visual scoring of EEG data permitted sleep staging. We derived a functional thalamic parcellation during wakefulness by computing seed-based FC, measured between thalamic voxels and a set of pre-defined cortical regions. Sleep differentially affected FC between these distinct thalamic subdivisions and their associated cortical projections, with significant increases in FC during sleep restricted to sensorimotor connections. In contrast, intra-thalamic FC, both within and between functional thalamic subdivisions, showed significant increases with advancement into sleep. This work demonstrates the complexity and state-specific nature of functional thalamic relationships--both with the cortex and internally--over the sleep/wake cycle, and further highlights the importance of a thalamocortical focus in the study of sleep mechanisms.
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Affiliation(s)
- Joanne R Hale
- School of Psychology, University of Birmingham, Birmingham, UK.
| | - Thomas P White
- School of Psychology, University of Birmingham, Birmingham, UK
| | | | | | - David T Rollings
- School of Psychology, University of Birmingham, Birmingham, UK; Department of Neurophysiology, Queen Elizabeth Hospital, Birmingham, UK
| | - Sakhvinder Khalsa
- School of Psychology, University of Birmingham, Birmingham, UK; Department of Neuropsychiatry, The Barberry National Centre for Mental Health, Birmingham, UK
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42
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Ong JL, Kong D, Chia TT, Tandi J, Thomas Yeo B, Chee MW. Co-activated yet disconnected—Neural correlates of eye closures when trying to stay awake. Neuroimage 2015; 118:553-62. [DOI: 10.1016/j.neuroimage.2015.03.085] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 03/24/2015] [Accepted: 03/24/2015] [Indexed: 12/25/2022] Open
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43
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Bettinardi RG, Tort-Colet N, Ruiz-Mejias M, Sanchez-Vives MV, Deco G. Gradual emergence of spontaneous correlated brain activity during fading of general anesthesia in rats: Evidences from fMRI and local field potentials. Neuroimage 2015; 114:185-98. [PMID: 25804643 PMCID: PMC4461308 DOI: 10.1016/j.neuroimage.2015.03.037] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 03/05/2015] [Accepted: 03/14/2015] [Indexed: 12/11/2022] Open
Abstract
Intrinsic brain activity is characterized by the presence of highly structured networks of correlated fluctuations between different regions of the brain. Such networks encompass different functions, whose properties are known to be modulated by the ongoing global brain state and are altered in several neurobiological disorders. In the present study, we induced a deep state of anesthesia in rats by means of a ketamine/medetomidine peritoneal injection, and analyzed the time course of the correlation between the brain activity in different areas while anesthesia spontaneously decreased over time. We compared results separately obtained from fMRI and local field potentials (LFPs) under the same anesthesia protocol, finding that while most profound phases of anesthesia can be described by overall sparse connectivity, stereotypical activity and poor functional integration, during lighter states different frequency-specific functional networks emerge, endowing the gradual restoration of structured large-scale activity seen during rest. Noteworthy, our in vivo results show that those areas belonging to the same functional network (the default-mode) exhibited sustained correlated oscillations around 10 Hz throughout the protocol, suggesting the presence of a specific functional backbone that is preserved even during deeper phases of anesthesia. Finally, the overall pattern of results obtained from both imaging and in vivo-recordings suggests that the progressive emergence from deep anesthesia is reflected by a corresponding gradual increase of organized correlated oscillations across the cortex. Rat brain activity was recorded while anesthesia spontaneously decreased over time. Fading of anesthesia modulates the overall pattern of brain structured co-activations. Areas of the same network show frequency-specific coupling even in deep anesthesia. Light anesthesia is characterized by the gradual emergence of large-scale connectivity. Correlated band-limited oscillations distinguish between states and network properties.
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Affiliation(s)
- Ruggero G Bettinardi
- Center for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona 08018, Spain.
| | - Núria Tort-Colet
- Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain
| | - Marcel Ruiz-Mejias
- Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain
| | - Maria V Sanchez-Vives
- Institut D' Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona 08036, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
| | - Gustavo Deco
- Center for Brain and Cognition, Computational Neuroscience Group, Universitat Pompeu Fabra, Barcelona 08018, Spain; Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona 08010, Spain
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44
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What Is Lost During Dreamless Sleep: The Relationship Between Neural Connectivity Patterns and Consciousness. JOURNAL OF EUROPEAN PSYCHOLOGY STUDENTS 2014. [DOI: 10.5334/jeps.cj] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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45
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Larson-Prior LJ, Ju YE, Galvin JE. Cortical-subcortical interactions in hypersomnia disorders: mechanisms underlying cognitive and behavioral aspects of the sleep-wake cycle. Front Neurol 2014; 5:165. [PMID: 25309500 PMCID: PMC4160996 DOI: 10.3389/fneur.2014.00165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 08/18/2014] [Indexed: 01/01/2023] Open
Abstract
Subcortical circuits mediating sleep–wake functions have been well characterized in animal models, and corroborated by more recent human studies. Disruptions in these circuits have been identified in hypersomnia disorders (HDs) such as narcolepsy and Kleine–Levin Syndrome, as well as in neurodegenerative disorders expressing excessive daytime sleepiness. However, the behavioral expression of sleep–wake functions is not a simple on-or-off state determined by subcortical circuits, but encompasses a complex range of behaviors determined by the interaction between cortical networks and subcortical circuits. While conceived as disorders of sleep, HDs are equally disorders of wake, representing a fundamental instability in neural state characterized by lapses of alertness during wake. These episodic lapses in alertness and wakefulness are also frequently seen in neurodegenerative disorders where electroencephalogram demonstrates abnormal function in cortical regions associated with cognitive fluctuations (CFs). Moreover, functional connectivity MRI shows instability of cortical networks in individuals with CFs. We propose that the inability to stabilize neural state due to disruptions in the sleep–wake control networks is common to the sleep and cognitive dysfunctions seen in hypersomnia and neurodegenerative disorders.
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Affiliation(s)
- Linda J Larson-Prior
- Department of Radiology, Washington University School of Medicine , St. Louis, MO , USA ; Department of Neurology, Washington University School of Medicine , St. Louis, MO , USA
| | - Yo-El Ju
- Department of Neurology, Washington University School of Medicine , St. Louis, MO , USA
| | - James E Galvin
- Departments of Neurology, New York University Langone School of Medicine , New York, NY , USA ; Department of Psychiatry, New York University Langone School of Medicine , New York, NY , USA ; Department of Population Health, New York University Langone School of Medicine , New York, NY , USA
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Abstract
The issue of integration in neural networks is intimately connected with that of consciousness. In this paper, integration as an effective level of physical organization is contrasted with a methodological integrative approach. Understanding how consciousness arises out of neural processes requires a model of integration in just causal physical terms. Based on a set of feasible criteria (physical grounding, causal efficacy, no circularity and scaling), a causal account of physical integration for consciousness centered on joint causation is outlined.
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Affiliation(s)
- Riccardo Manzotti
- Institute "GP Fabris", IULM University, via Carlo Bo, 8, 20143 Milano, Italy
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47
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Pillay S, Vizuete J, Liu X, Juhasz G, Hudetz AG. Brainstem stimulation augments information integration in the cerebral cortex of desflurane-anesthetized rats. Front Integr Neurosci 2014; 8:8. [PMID: 24605091 PMCID: PMC3932553 DOI: 10.3389/fnint.2014.00008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 01/13/2014] [Indexed: 11/16/2022] Open
Abstract
States of consciousness have been associated with information integration in the brain as modulated by anesthesia and the ascending arousal system. The present study was designed to test the hypothesis that electrical stimulation of the oral part of the pontine reticular nucleus (PnO) can augment information integration in the cerebral cortex of anesthetized rats. Extracellular unit activity and local field potentials were recorded in freely moving animals from parietal association (PtA) and secondary visual (V2) cortices via chronically implanted microwire arrays at three levels of anesthesia produced by desflurane: 3.5, 4.5, and 6.0% (where 4.5% corresponds to that critical for the loss of consciousness). Information integration was characterized by integration (multiinformation) and interaction entropy, estimated from the statistical distribution of coincident spike patterns. PnO stimulation elicited electrocortical activation as indicated by the reductions in δ- and θ-band powers at the intermediate level of anesthesia. PnO stimulation augmented integration from 1.13 ± 0.03 to 6.12 ± 1.98 × 103 bits and interaction entropy from 0.44 ± 0.11 to 2.18 ± 0.72 × 103 bits; these changes were most consistent in the PtA at all desflurane concentrations. Stimulation of the retina with discrete light flashes after PnO stimulation elicited an additional 166 ± 25 and 92 ± 12% increase in interaction entropy in V2 during light and intermediate levels. The results suggest that the PnO may modulate spontaneous ongoing and sensory stimulus-related cortical information integration under anesthesia.
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Affiliation(s)
- Siveshigan Pillay
- Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA
| | - Jeannette Vizuete
- Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA
| | - Xiping Liu
- Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA
| | - Gabor Juhasz
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University Budapest, Hungary
| | - Anthony G Hudetz
- Department of Anesthesiology, Medical College of Wisconsin Milwaukee, WI, USA
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48
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Lee GMH, Fattinger S, Mouthon AL, Noirhomme Q, Huber R. Electroencephalogram approximate entropy influenced by both age and sleep. Front Neuroinform 2013; 7:33. [PMID: 24367328 PMCID: PMC3852001 DOI: 10.3389/fninf.2013.00033] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 11/19/2013] [Indexed: 12/03/2022] Open
Abstract
The use of information-based measures to assess changes in conscious state is an increasingly popular topic. Though recent results have seemed to justify the merits of such methods, little has been done to investigate the applicability of such measures to children. For our work, we used the approximate entropy (ApEn), a measure previously shown to correlate with changes in conscious state when applied to the electroencephalogram (EEG), and sought to confirm whether previously reported trends in adult ApEn values across wake and sleep were present in children. Besides validating the prior findings that ApEn decreases from wake to sleep (including wake, rapid eye movement (REM) sleep, and non-REM sleep) in adults, we found that previously reported ApEn decreases across vigilance states in adults were also present in children (ApEn trends for both age groups: wake > REM sleep > non-REM sleep). When comparing ApEn values between age groups, adults had significantly larger ApEn values than children during wakefulness. After the application of an 8 Hz high-pass filter to the EEG signal, ApEn values were recalculated. The number of electrodes with significant vigilance state effects dropped from all 109 electrodes with the original 1 Hz filter to 1 electrode with the 8 Hz filter. The number of electrodes with significant age effects dropped from 10 to 4. Our results support the notion that ApEn can reliably distinguish between vigilance states, with low-frequency sleep-related oscillations implicated as the driver of changes between vigilance states. We suggest that the observed differences between adult and child ApEn values during wake may reflect differences in connectivity between age groups, a factor which may be important in the use of EEG to measure consciousness.
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Affiliation(s)
- Gerick M H Lee
- Institute of Neuroinformatics, University of Zurich and ETH Zurich Zurich, Switzerland ; Child Development Center, University Children's Hospital Zurich Zurich, Switzerland
| | - Sara Fattinger
- Child Development Center, University Children's Hospital Zurich Zurich, Switzerland
| | - Anne-Laure Mouthon
- Child Development Center, University Children's Hospital Zurich Zurich, Switzerland
| | - Quentin Noirhomme
- Coma Science Group, Neurology Department, Cyclotron Research Centre, University Hospital of Liège, University of Liège Liège, Belgium
| | - Reto Huber
- Child Development Center, University Children's Hospital Zurich Zurich, Switzerland
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49
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George MS, Massimini M. Using Brain Stimulation to Create Thoughts, Retrieve and Alter Memories, and Measure Consciousness – A Discussion of Recent Research. Brain Stimul 2013; 6:835-6. [DOI: 10.1016/j.brs.2013.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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50
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Boly M, Seth AK, Wilke M, Ingmundson P, Baars B, Laureys S, Edelman DB, Tsuchiya N. Consciousness in humans and non-human animals: recent advances and future directions. Front Psychol 2013; 4:625. [PMID: 24198791 PMCID: PMC3814086 DOI: 10.3389/fpsyg.2013.00625] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 08/24/2013] [Indexed: 12/30/2022] Open
Abstract
This joint article reflects the authors' personal views regarding noteworthy advances in the neuroscience of consciousness in the last 10 years, and suggests what we feel may be promising future directions. It is based on a small conference at the Samoset Resort in Rockport, Maine, USA, in July of 2012, organized by the Mind Science Foundation of San Antonio, Texas. Here, we summarize recent advances in our understanding of subjectivity in humans and other animals, including empirical, applied, technical, and conceptual insights. These include the evidence for the importance of fronto-parietal connectivity and of “top-down” processes, both of which enable information to travel across distant cortical areas effectively, as well as numerous dissociations between consciousness and cognitive functions, such as attention, in humans. In addition, we describe the development of mental imagery paradigms, which made it possible to identify covert awareness in non-responsive subjects. Non-human animal consciousness research has also witnessed substantial advances on the specific role of cortical areas and higher order thalamus for consciousness, thanks to important technological enhancements. In addition, much progress has been made in the understanding of non-vertebrate cognition relevant to possible conscious states. Finally, major advances have been made in theories of consciousness, and also in their comparison with the available evidence. Along with reviewing these findings, each author suggests future avenues for research in their field of investigation.
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Affiliation(s)
- Melanie Boly
- Department of Neurology, University of Wisconsin Madison, WI, USA ; Department of Psychiatry, Center for Sleep and Consciousness, University of Wisconsin Madison, WI, USA ; Coma Science Group, Cyclotron Research Centre and Neurology Department, University of Liege and CHU Sart Tilman Hospital Liege, Belgium
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