551
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Noirhomme Q, Brecheisen R, Lesenfants D, Antonopoulos G, Laureys S. "Look at my classifier's result": Disentangling unresponsive from (minimally) conscious patients. Neuroimage 2015; 145:288-303. [PMID: 26690804 DOI: 10.1016/j.neuroimage.2015.12.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 11/12/2015] [Accepted: 12/04/2015] [Indexed: 12/22/2022] Open
Abstract
Given the fact that clinical bedside examinations can have a high rate of misdiagnosis, machine learning techniques based on neuroimaging and electrophysiological measurements are increasingly being considered for comatose patients and patients with unresponsive wakefulness syndrome, a minimally conscious state or locked-in syndrome. Machine learning techniques have the potential to move from group-level statistical results to personalized predictions in a clinical setting. They have been applied for the purpose of (1) detecting changes in brain activation during functional tasks, equivalent to a behavioral command-following test and (2) estimating signs of consciousness by analyzing measurement data obtained from multiple subjects in resting state. In this review, we provide a comprehensive overview of the literature on both approaches and discuss the translation of present findings to clinical practice. We found that most studies struggle with the difficulty of establishing a reliable behavioral assessment and fluctuations in the patient's levels of arousal. Both these factors affect the training and validation of machine learning methods to a considerable degree. In studies involving more than 50 patients, small to moderate evidence was found for the presence of signs of consciousness or good outcome, where one study even showed strong evidence for good outcome.
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Affiliation(s)
- Quentin Noirhomme
- Brain Innovation BV, Maastricht, Netherlands; Department of Cognitive Neuroscience, Faculty Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands; Cyclotron Research Centre, University of Liege, Liege, Belgium.
| | - Ralph Brecheisen
- Brain Innovation BV, Maastricht, Netherlands; Department of Cognitive Neuroscience, Faculty Psychology and Neuroscience, Maastricht University, Maastricht, Netherlands
| | - Damien Lesenfants
- School of Engineering and Institute for Brain Science, Brown University, Providence, Rhode Island, USA
| | | | - Steven Laureys
- Coma Science Group, University Hospital of Liege, Liege, Belgium
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552
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Naci L, Sinai L, Owen AM. Detecting and interpreting conscious experiences in behaviorally non-responsive patients. Neuroimage 2015; 145:304-313. [PMID: 26679327 DOI: 10.1016/j.neuroimage.2015.11.059] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Revised: 10/31/2015] [Accepted: 11/24/2015] [Indexed: 11/30/2022] Open
Abstract
Decoding the contents of consciousness from brain activity is one of the most challenging frontiers of cognitive neuroscience. The ability to interpret mental content without recourse to behavior is most relevant for understanding patients who may be demonstrably conscious, but entirely unable to speak or move willfully in any way, precluding any systematic investigation of their conscious experience. The lack of consistent behavioral responsivity engenders unique challenges to decoding any conscious experiences these patients may have solely based on their brain activity. For this reason, paradigms that have been successful in healthy individuals cannot serve to interpret conscious mental states in this patient group. Until recently, patient studies have used structured instructions to elicit willful modulation of brain activity according to command, in order to decode the presence of willful brain-based responses in this patient group. In recent work, we have used naturalistic paradigms, such as watching a movie or listening to an audio-story, to demonstrate that a common neural code supports conscious experiences in different individuals. Moreover, we have demonstrated that this code can be used to interpret the conscious experiences of a patient who had remained non-responsive for several years. This approach is easy to administer, brief, and does not require compliance with task instructions. Rather, it engages attention naturally through meaningful stimuli that are similar to the real-world sensory information in a patient's environment. Therefore, it may be particularly suited to probing consciousness and revealing residual brain function in highly impaired, acute, patients in a comatose state, thus helping to improve diagnostication and prognostication for this vulnerable patient group from the critical early stages of severe brain-injury.
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Affiliation(s)
- Lorina Naci
- The Brain and Mind Institute, Department of Psychology, University of Western ON, London N6A 5B7, Canada.
| | - Leah Sinai
- The Brain and Mind Institute, Department of Psychology, University of Western ON, London N6A 5B7, Canada
| | - Adrian M Owen
- The Brain and Mind Institute, Department of Psychology, University of Western ON, London N6A 5B7, Canada
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553
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The psychosis-like effects of Δ(9)-tetrahydrocannabinol are associated with increased cortical noise in healthy humans. Biol Psychiatry 2015; 78:805-13. [PMID: 25913109 PMCID: PMC4627857 DOI: 10.1016/j.biopsych.2015.03.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 03/06/2015] [Accepted: 03/20/2015] [Indexed: 11/20/2022]
Abstract
BACKGROUND Drugs that induce psychosis may do so by increasing the level of task-irrelevant random neural activity or neural noise. Increased levels of neural noise have been demonstrated in psychotic disorders. We tested the hypothesis that neural noise could also be involved in the psychotomimetic effects of delta-9-tetrahydrocannabinol (Δ(9)-THC), the principal active constituent of cannabis. METHODS Neural noise was indexed by measuring the level of randomness in the electroencephalogram during the prestimulus baseline period of an oddball task using Lempel-Ziv complexity, a nonlinear measure of signal randomness. The acute, dose-related effects of Δ(9)-THC on Lempel-Ziv complexity and signal power were studied in humans (n = 24) who completed 3 test days during which they received intravenous Δ(9)-THC (placebo, .015 and .03 mg/kg) in a double-blind, randomized, crossover, and counterbalanced design. RESULTS Δ(9)-THC increased neural noise in a dose-related manner. Furthermore, there was a strong positive relationship between neural noise and the psychosis-like positive and disorganization symptoms induced by Δ(9)-THC, which was independent of total signal power. Instead, there was no relationship between noise and negative-like symptoms. In addition, Δ(9)-THC reduced total signal power during both active drug conditions compared with placebo, but no relationship was detected between signal power and psychosis-like symptoms. CONCLUSIONS At doses that produced psychosis-like effects, Δ(9)-THC increased neural noise in humans in a dose-dependent manner. Furthermore, increases in neural noise were related with increases in Δ(9)-THC-induced psychosis-like symptoms but not negative-like symptoms. These findings suggest that increases in neural noise may contribute to the psychotomimetic effects of Δ(9)-THC.
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554
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Kudenchuk PJ, Sandroni C, Drinhaus HR, Böttiger BW, Cariou A, Sunde K, Dworschak M, Taccone FS, Deye N, Friberg H, Laureys S, Ledoux D, Oddo M, Legriel S, Hantson P, Diehl JL, Laterre PF. Breakthrough in cardiac arrest: reports from the 4th Paris International Conference. Ann Intensive Care 2015; 5:22. [PMID: 26380990 PMCID: PMC4573754 DOI: 10.1186/s13613-015-0064-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 08/18/2015] [Indexed: 02/08/2023] Open
Abstract
Jean-Luc Diehl The French Intensive Care Society organized on 5th and 6th June 2014 its 4th "Paris International Conference in Intensive Care", whose principle is to bring together the best international experts on a hot topic in critical care medicine. The 2014 theme was "Breakthrough in cardiac arrest", with many high-quality updates on epidemiology, public health data, pre-hospital and in-ICU cares. The present review includes short summaries of the major presentations, classified into six main chapters: Epidemiology of CA Pre-hospital management Post-resuscitation management: targeted temperature management Post-resuscitation management: optimizing organ perfusion and metabolic parameters Neurological assessment of brain damages Public healthcare.
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Affiliation(s)
| | - Claudio Sandroni
- Department of Anaesthesiology and Intensive Care, Catholic University School of Medicine, Rome, Italy.
| | - Hendrik R Drinhaus
- Department of Anaesthesiology and Intensive Care Medicine, University of Koeln, Cologne, Germany.
| | - Bernd W Böttiger
- Department of Anaesthesiology and Intensive Care Medicine, University of Koeln, Cologne, Germany.
| | - Alain Cariou
- Medical Intensive Care Unit, AP-HP, Cochin Hospital, Paris, France.
- Paris Descartes University and Sorbonne Paris Cité-Medical School and INSERM U970 (Team 4), Cardiovascular Research Center, European Georges Pompidou Hospital, Paris, France.
| | - Kjetil Sunde
- Division of Emergencies and Critical Care, Department of Anaesthesiology, Surgical Intensive Care Unit Ullevål, Oslo University Hospital, Oslo, Norway.
| | - Martin Dworschak
- Division of Cardiothoracic and Vascular Anesthesia and Intensive Care Medicine, Vienna General Hospital, Medical University Vienna, Vienna, Austria.
| | - Fabio Silvio Taccone
- Department of Intensive Care, Laboratoire de Recherche Experimentale, Erasme Hospital, Brussels, Belgium.
| | - Nicolas Deye
- Medical Intensive Care Unit, AP-HP, Lariboisière University Hospital, Inserm U942, Paris, France.
| | - Hans Friberg
- Anaesthesiology and Intensive Care Medicine, Skåne University Hospital, Lund University, Lund, Sweden.
| | - Steven Laureys
- Coma Science Group, Cyclotron Research Centre, University of Liège and Liège 2 Department of Neurology, University Hospital of Liège, Liège, Belgium.
| | - Didier Ledoux
- Coma Science Group, Cyclotron Research Centre, University of Liège and Department of Intensive Care Medicine, University Hospital of Liège, Liège, Belgium.
| | - Mauro Oddo
- Department of Intensive Care Medicine, Faculty of Biology and Medicine, CHUV-University Hospital, Lausanne, Switzerland.
| | - Stéphane Legriel
- Intensive Care Unit, Centre Hospitalier de Versailles, Le Chesnay, France.
| | - Philippe Hantson
- Department of Intensive Care, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.
| | - Jean-Luc Diehl
- Medical Intensive Care Unit, AP-HP, European Georges Pompidou Hospital, Paris Descartes University and Sorbonne Paris Cité-Medical School, Paris, France.
| | - Pierre-Francois Laterre
- Department of Intensive Care, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain Brussels, Brussels, Belgium.
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555
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Tsuchiya N, Wilke M, Frässle S, Lamme VA. No-Report Paradigms: Extracting the True Neural Correlates of Consciousness. Trends Cogn Sci 2015; 19:757-770. [DOI: 10.1016/j.tics.2015.10.002] [Citation(s) in RCA: 205] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 10/04/2015] [Accepted: 10/12/2015] [Indexed: 10/22/2022]
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556
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Assessment of Event-Related EEG Power After Single-Pulse TMS in Unresponsive Wakefulness Syndrome and Minimally Conscious State Patients. Brain Topogr 2015; 29:322-33. [DOI: 10.1007/s10548-015-0461-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 11/07/2015] [Indexed: 11/26/2022]
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557
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Sarasso S, Boly M, Napolitani M, Gosseries O, Charland-Verville V, Casarotto S, Rosanova M, Casali AG, Brichant JF, Boveroux P, Rex S, Tononi G, Laureys S, Massimini M. Consciousness and Complexity during Unresponsiveness Induced by Propofol, Xenon, and Ketamine. Curr Biol 2015; 25:3099-105. [PMID: 26752078 DOI: 10.1016/j.cub.2015.10.014] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/28/2015] [Accepted: 10/05/2015] [Indexed: 10/22/2022]
Abstract
A common endpoint of general anesthetics is behavioral unresponsiveness, which is commonly associated with loss of consciousness. However, subjects can become disconnected from the environment while still having conscious experiences, as demonstrated by sleep states associated with dreaming. Among anesthetics, ketamine is remarkable in that it induces profound unresponsiveness, but subjects often report "ketamine dreams" upon emergence from anesthesia. Here, we aimed at assessing consciousness during anesthesia with propofol, xenon, and ketamine, independent of behavioral responsiveness. To do so, in 18 healthy volunteers, we measured the complexity of the cortical response to transcranial magnetic stimulation (TMS)--an approach that has proven helpful in assessing objectively the level of consciousness irrespective of sensory processing and motor responses. In addition, upon emergence from anesthesia, we collected reports about conscious experiences during unresponsiveness. Both frontal and parietal TMS elicited a low-amplitude electroencephalographic (EEG) slow wave corresponding to a local pattern of cortical activation with low complexity during propofol anesthesia, a high-amplitude EEG slow wave corresponding to a global, stereotypical pattern of cortical activation with low complexity during xenon anesthesia, and a wakefulness-like, complex spatiotemporal activation pattern during ketamine anesthesia. Crucially, participants reported no conscious experience after emergence from propofol and xenon anesthesia, whereas after ketamine they reported long, vivid dreams unrelated to the external environment. These results are relevant because they suggest that brain complexity may be sensitive to the presence of disconnected consciousness in subjects who are considered unconscious based on behavioral responses.
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Affiliation(s)
- Simone Sarasso
- Dipartimento di Scienze Biomediche e Cliniche "L. Sacco", Università degli Studi di Milano, 20157 Milan, Italy
| | - Melanie Boly
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA; Department of Neurology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Martino Napolitani
- Dipartimento di Scienze Biomediche e Cliniche "L. Sacco", Università degli Studi di Milano, 20157 Milan, Italy; Dipartimento di Scienze Clinico-chirurgiche, Diagnostiche e Pediatriche, Sezione di Anestesia Rianimazione e Terapia Antalgica, Università degli Studi di Pavia, SC Anestesia e Rianimazione, Fondazione IRCCS Policlinico S. Matteo, 27100 Pavia, Italy
| | - Olivia Gosseries
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA; Coma Science Group, University and University Hospital of Liège, GIGA-Research B34, 4000 Liège, Belgium
| | - Vanessa Charland-Verville
- Coma Science Group, University and University Hospital of Liège, GIGA-Research B34, 4000 Liège, Belgium
| | - Silvia Casarotto
- Dipartimento di Scienze Biomediche e Cliniche "L. Sacco", Università degli Studi di Milano, 20157 Milan, Italy
| | - Mario Rosanova
- Dipartimento di Scienze Biomediche e Cliniche "L. Sacco", Università degli Studi di Milano, 20157 Milan, Italy
| | - Adenauer Girardi Casali
- Institute of Science and Technology, Federal University of São Paulo, 12231-280 São José dos Campos, Brazil
| | - Jean-Francois Brichant
- Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman University Hospital, University of Liège, 4000 Liège, Belgium
| | - Pierre Boveroux
- Department of Anesthesia and Intensive Care Medicine, CHU Sart Tilman University Hospital, University of Liège, 4000 Liège, Belgium
| | - Steffen Rex
- Department of Anaesthesiology, University Hospitals of the KU Leuven, KU Leuven, 3000 Leuven, Belgium; Department of Cardiovascular Sciences, University Hospitals of the KU Leuven, KU Leuven, 3000 Leuven, Belgium
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA
| | - Steven Laureys
- Coma Science Group, University and University Hospital of Liège, GIGA-Research B34, 4000 Liège, Belgium.
| | - Marcello Massimini
- Dipartimento di Scienze Biomediche e Cliniche "L. Sacco", Università degli Studi di Milano, 20157 Milan, Italy; Istituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, 20148 Milan, Italy.
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558
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Abstract
BACKGROUND Neuronal interactions are fundamental for information processing, cognition, and consciousness. Anesthetics reduce spontaneous cortical activity; however, neuronal reactivity to sensory stimuli is often preserved or augmented. How sensory stimulus-related neuronal interactions change under anesthesia has not been elucidated. In this study, the authors investigated the visual stimulus-related cortical neuronal interactions during stepwise emergence from desflurane anesthesia. METHODS Parallel spike trains were recorded with 64-contact extracellular microelectrode arrays from the primary visual cortex of chronically instrumented, unrestrained rats (N = 6) at 8, 6, 4, and 2% desflurane anesthesia and wakefulness. Light flashes were delivered to the retina by transcranial illumination at 5- to 15-s randomized intervals. Information theoretical indices, integration and interaction complexity, were calculated from the probability distribution of coincident spike patterns and used to quantify neuronal interactions before and after flash stimulation. RESULTS Integration and complexity showed significant negative associations with desflurane concentration (N = 60). Flash stimulation increased integration and complexity at all anesthetic levels (N = 60); the effect on complexity was reduced in wakefulness. During stepwise withdrawal of desflurane, the largest increase in integration (74%) and poststimulus complexity (35%) occurred before reaching 4% desflurane concentration-a level associated with the recovery of consciousness according to the rats' righting reflex. CONCLUSIONS Neuronal interactions in the cerebral cortex are augmented during emergence from anesthesia. Visual flash stimuli enhance neuronal interactions in both wakefulness and anesthesia; the increase in interaction complexity is attenuated as poststimulus complexity reaches plateau. The critical changes in cortical neuronal interactions occur during transition to consciousness.
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559
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Heine L, Castro M, Martial C, Tillmann B, Laureys S, Perrin F. Exploration of Functional Connectivity During Preferred Music Stimulation in Patients with Disorders of Consciousness. Front Psychol 2015; 6:1704. [PMID: 26617542 PMCID: PMC4637404 DOI: 10.3389/fpsyg.2015.01704] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/22/2015] [Indexed: 01/26/2023] Open
Abstract
Preferred music is a highly emotional and salient stimulus, which has previously been shown to increase the probability of auditory cognitive event-related responses in patients with disorders of consciousness (DOC). To further investigate whether and how music modifies the functional connectivity of the brain in DOC, five patients were assessed with both a classical functional connectivity scan (control condition), and a scan while they were exposed to their preferred music (music condition). Seed-based functional connectivity (left or right primary auditory cortex), and mean network connectivity of three networks linked to conscious sound perception were assessed. The auditory network showed stronger functional connectivity with the left precentral gyrus and the left dorsolateral prefrontal cortex during music as compared to the control condition. Furthermore, functional connectivity of the external network was enhanced during the music condition in the temporo-parietal junction. Although caution should be taken due to small sample size, these results suggest that preferred music exposure might have effects on patients auditory network (implied in rhythm and music perception) and on cerebral regions linked to autobiographical memory.
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Affiliation(s)
- Lizette Heine
- Coma Science Group, GIGA & Cyclotron Research Center and Neurology Department, University and University Hospital of LiègeLiège, Belgium
- Auditory Cognition and Psychoacoustics Team – Lyon Neuroscience Research Center (UCBL, CNRS, UMR 5292, INSERM U1028)Lyon, France
| | - Maïté Castro
- Auditory Cognition and Psychoacoustics Team – Lyon Neuroscience Research Center (UCBL, CNRS, UMR 5292, INSERM U1028)Lyon, France
| | - Charlotte Martial
- Coma Science Group, GIGA & Cyclotron Research Center and Neurology Department, University and University Hospital of LiègeLiège, Belgium
| | - Barbara Tillmann
- Auditory Cognition and Psychoacoustics Team – Lyon Neuroscience Research Center (UCBL, CNRS, UMR 5292, INSERM U1028)Lyon, France
| | - Steven Laureys
- Coma Science Group, GIGA & Cyclotron Research Center and Neurology Department, University and University Hospital of LiègeLiège, Belgium
| | - Fabien Perrin
- Auditory Cognition and Psychoacoustics Team – Lyon Neuroscience Research Center (UCBL, CNRS, UMR 5292, INSERM U1028)Lyon, France
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560
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Onofrj M, Bonanni L, Delli Pizzi S, Caulo M, Onofrj V, Thomas A, Tartaro A, Franciotti R. Cortical Activation During Levitation and Tentacular Movements of Corticobasal Syndrome. Medicine (Baltimore) 2015; 94:e1977. [PMID: 26559277 PMCID: PMC4912271 DOI: 10.1097/md.0000000000001977] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Levitation and tentacular movements (LTM) are considered specific, yet rare (30%), features of Corticobasal Syndrome (CBS), and are erroneously classified as alien hand. Our study focuses on these typical involuntary movements and aims to highlight possible neural correlates.LTM were recognizable during functional magnetic resonance imaging (fMRI) in 4 of 19 CBS patients. FMRI activity was evaluated with an activation recognition program for movements, during LTM, consisting of levitaton and finger writhing, and compared with the absence of movement (rest) and voluntary movements (VM), similar to LTM, of affected and unaffected arm-hand. FMRI acquisition blocks were balanced in order to match LTM blocks with rest and VM conditions. In 1 of the 4 patients, fMRI was acquired only during LTM and with a different equipment.Despite variable intensity and range of involuntary movements, evidenced by videos, fMRI showed, during LTM, a significant (P<0.05-0.001) activation only of the contralateral primary motor cortex (M1). Voluntary movements of the affected and unaffected arm elicited the known network including frontal, supplementary, sensory-motor cortex, and cerebellum. Willed movements of the LTM-affected arm induced higher and wider activation of contralateral M1 compared with the unaffected arm.The isolated activation of M1 suggests that LTM is a cortical disinhibition symptom, not involving a network. Higher activation of M1 during VM confirms that M1 excitability changes occur in CBS. Our study calls, finally, attention to the necessity to separate LTM from other alien hand phenomena.
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Affiliation(s)
- Marco Onofrj
- From the Department of Neuroscience, Imaging and Clinical Sciences "G. d'Annunzio" University (MO, LB, SDP, MC, AT, AT, RF); Aging Research Centre, Ce.S.I. (MO, LB, SD, AT, RF); ITAB, "G. d'Annunzio" University Foundation, Chieti (SDP, MC, AT, RF); and Dipartimento Di BioImmagini, Università Cattolica SC, Roma, Italy (VO)
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561
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Jao T, Schröter M, Chen CL, Cheng YF, Lo CYZ, Chou KH, Patel AX, Lin WC, Lin CP, Bullmore ET. Functional brain network changes associated with clinical and biochemical measures of the severity of hepatic encephalopathy. Neuroimage 2015; 122:332-44. [DOI: 10.1016/j.neuroimage.2015.07.068] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 07/05/2015] [Accepted: 07/26/2015] [Indexed: 01/01/2023] Open
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562
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Jao T, Li CW, Vértes PE, Wu CW, Achard S, Hsieh CH, Liou CH, Chen JH, Bullmore ET. Large-Scale Functional Brain Network Reorganization During Taoist Meditation. Brain Connect 2015; 6:9-24. [PMID: 26165867 DOI: 10.1089/brain.2014.0318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Meditation induces a distinct and reversible mental state that provides insights into brain correlates of consciousness. We explored brain network changes related to meditation by graph theoretical analysis of resting-state functional magnetic resonance imaging data. Eighteen Taoist meditators with varying levels of expertise were scanned using a within-subjects counterbalanced design during resting and meditation states. State-related differences in network topology were measured globally and at the level of individual nodes and edges. Although measures of global network topology, such as small-worldness, were unchanged, meditation was characterized by an extensive and expertise-dependent reorganization of the hubs (highly connected nodes) and edges (functional connections). Areas of sensory cortex, especially the bilateral primary visual and auditory cortices, and the bilateral temporopolar areas, which had the highest degree (or connectivity) during the resting state, showed the biggest decrease during meditation. Conversely, bilateral thalamus and components of the default mode network, mainly the bilateral precuneus and posterior cingulate cortex, had low degree in the resting state but increased degree during meditation. Additionally, these changes in nodal degree were accompanied by reorganization of anatomical orientation of the edges. During meditation, long-distance longitudinal (antero-posterior) edges increased proportionally, whereas orthogonal long-distance transverse (right-left) edges connecting bilaterally homologous cortices decreased. Our findings suggest that transient changes in consciousness associated with meditation introduce convergent changes in the topological and spatial properties of brain functional networks, and the anatomical pattern of integration might be as important as the global level of integration when considering the network basis for human consciousness.
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Affiliation(s)
- Tun Jao
- 1 Brain Mapping Unit and Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom .,2 Department of Neurology, National Taiwan University Hospital , Taipei, Taiwan
| | - Chia-Wei Li
- 3 Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University , Taipei, Taiwan
| | - Petra E Vértes
- 1 Brain Mapping Unit and Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom
| | - Changwei Wesley Wu
- 4 Graduate Institute of Biomedical Engineering, National Central University , Taoyuan, Taiwan
| | - Sophie Achard
- 5 Centre National de la Recherche Scientifique, Grenoble Image Parole Signal Automatique , Grenoble, France
| | - Chao-Hsien Hsieh
- 3 Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University , Taipei, Taiwan .,6 Neurobiology and Cognitive Science Center, National Taiwan University , Taipei, Taiwan
| | - Chien-Hui Liou
- 3 Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University , Taipei, Taiwan
| | - Jyh-Horng Chen
- 3 Interdisciplinary MRI/MRS Lab, Department of Electrical Engineering, National Taiwan University , Taipei, Taiwan
| | - Edward T Bullmore
- 1 Brain Mapping Unit and Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom .,7 Alternative Discovery and Development , GlaxoSmithKline, Cambridge, United Kingdom .,8 Cambridgeshire and Peterborough NHS Foundation Trust , Cambridge, United Kingdom
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563
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Kemmerer D. Are we ever aware of concepts? A critical question for the Global Neuronal Workspace, Integrated Information, and Attended Intermediate-Level Representation theories of consciousness. Neurosci Conscious 2015; 2015:niv006. [PMID: 30135741 PMCID: PMC6089087 DOI: 10.1093/nc/niv006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 08/24/2015] [Accepted: 09/02/2015] [Indexed: 01/13/2023] Open
Abstract
To locate consciousness in the flow of synaptic activity in the brain, we must first locate it in the flow of information processing in the mind. Two different positions have been debated for centuries. The liberal view maintains that the contents of experience include not only sensory, motor, and affective states, but also concepts and the thoughts they enter into. In contrast, the conservative view maintains that concepts have no intrinsic qualia of their own, and that the contents of experience are therefore restricted to sensory, motor, and affective states. Here I discuss how this long-standing controversy is relevant to several contemporary neuroscientific theories of consciousness. I do so, however, in a manner that is admittedly biased toward the conservative view, since I am among those who believe that it is more consistent than the liberal view with a number of key findings. I focus first on two of the most prominent neuroscientific theories of consciousness—namely, Stanislas Dehaene's Global Neuronal Workspace Theory and Giulio Tononi's Integrated Information Theory. I argue that because both of these approaches assume the liberal view, they are challenged in significant ways by data favoring the competing conservative view. I then turn to a third framework—namely, Jesse Prinz's Attended Intermediate-Level Representation Theory. I contend that because it explicitly endorses the conservative view, it has a unique advantage over the other two approaches. I also point out, however, that it has independent shortcomings that prevent it from achieving adequate explanatory coherence. I conclude by emphasizing that, if the conservative view is in fact correct, a central goal of future research should be to distinguish, at both psychological and neurobiological levels of analysis, between the following two kinds of information processing that often occur simultaneously: first, activation of the modality-specific sensory, motor, and affective representations that constitute the sole ingredients of conscious experiences; and second, activation of the conceptual representations that give those experiences meaning and that may even influence them in a top-down manner, but that never themselves reach awareness.
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Affiliation(s)
- David Kemmerer
- Department of Speech, Language, and Hearing Sciences, Purdue University and Department of Psychological Sciences, Purdue University
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564
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Cruse D, Young GB. The complexity of disorders of consciousness. Clin Neurophysiol 2015; 127:1001-1002. [PMID: 26412137 DOI: 10.1016/j.clinph.2015.08.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 08/27/2015] [Accepted: 08/28/2015] [Indexed: 10/23/2022]
Affiliation(s)
- Damian Cruse
- School of Psychology, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - G Bryan Young
- Department of Clinical Neurological Sciences, London Health Sciences Centre, London, Ont., Canada
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565
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Zhou DW, Mowrey DD, Tang P, Xu Y. Percolation Model of Sensory Transmission and Loss of Consciousness Under General Anesthesia. PHYSICAL REVIEW LETTERS 2015; 115:108103. [PMID: 26382705 PMCID: PMC4656020 DOI: 10.1103/physrevlett.115.108103] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Indexed: 06/05/2023]
Abstract
Neurons communicate with each other dynamically; how such communications lead to consciousness remains unclear. Here, we present a theoretical model to understand the dynamic nature of sensory activity and information integration in a hierarchical network, in which edges are stochastically defined by a single parameter p representing the percolation probability of information transmission. We validate the model by comparing the transmitted and original signal distributions, and we show that a basic version of this model can reproduce key spectral features clinically observed in electroencephalographic recordings of transitions from conscious to unconscious brain activities during general anesthesia. As p decreases, a steep divergence of the transmitted signal from the original was observed, along with a loss of signal synchrony and a sharp increase in information entropy in a critical manner; this resembles the precipitous loss of consciousness during anesthesia. The model offers mechanistic insights into the emergence of information integration from a stochastic process, laying the foundation for understanding the origin of cognition.
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Affiliation(s)
- David W. Zhou
- Department of Anesthesiology, University of Pittsburgh School of Medicine
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA
| | - David D. Mowrey
- Department of Anesthesiology, University of Pittsburgh School of Medicine
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine
| | - Pei Tang
- Department of Anesthesiology, University of Pittsburgh School of Medicine
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine
| | - Yan Xu
- Department of Anesthesiology, University of Pittsburgh School of Medicine
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine
- Department of Structural Biology, University of Pittsburgh School of Medicine
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566
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Decoupled temporal variability and signal synchronization of spontaneous brain activity in loss of consciousness: An fMRI study in anesthesia. Neuroimage 2015; 124:693-703. [PMID: 26343319 DOI: 10.1016/j.neuroimage.2015.08.062] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 02/02/2023] Open
Abstract
Two aspects of the low frequency fluctuations of spontaneous brain activity have been proposed which reflect the complex and dynamic features of resting-state activity, namely temporal variability and signal synchronization. The relationship between them, especially its role in consciousness, nevertheless remains unclear. Our study examined the temporal variability and signal synchronization of spontaneous brain activity, as well as their relationship during loss of consciousness. We applied an intra-subject design of resting-state functional magnetic resonance imaging (rs-fMRI) in two conditions: during wakefulness, and under anesthesia with clinical unconsciousness. In addition, an independent group of patients with disorders of consciousness (DOC) was included in order to test the reliability of our findings. We observed a global reduction in the temporal variability, local and distant brain signal synchronization for subjects during anesthesia. Importantly, we found a link between temporal variability and both local and distant signal synchronizations during wakefulness: the higher the degree of temporal variability, the higher its intra-regional homogeneity and inter-regional functional connectivity. In contrast, this link was broken down under anesthesia, implying a decoupling between temporal variability and signal synchronization; this decoupling was reproduced in patients with DOC. Our results suggest that there exist some as yet unclear physiological mechanisms of consciousness which "couple" the two mathematically independent measures, temporal variability and signal synchronization of spontaneous brain activity. Our findings not only extend our current knowledge of the neural correlates of anesthetic-induced unconsciousness, but have implications for both computational neural modeling and clinical practice, such as in the diagnosis of loss of consciousness in patients with DOC.
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567
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Affiliation(s)
- Lukasz M Konopka
- Lukasz M. Konopka, Department of Psychiatry, Loyola Medical Center, Maywood and Chicago Brain Institute, Rolling Meadows Il, USA,
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568
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Stamm M, Aru J, Rutiku R, Bachmann T. Occipital long-interval paired pulse TMS leads to slow wave components in NREM sleep. Conscious Cogn 2015; 35:78-87. [DOI: 10.1016/j.concog.2015.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 04/25/2015] [Accepted: 04/28/2015] [Indexed: 11/25/2022]
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569
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Smart CM, Giacino JT. Exploring caregivers’ knowledge of and receptivity toward novel diagnostic tests and treatments for persons with post-traumatic disorders of consciousness. NeuroRehabilitation 2015; 37:117-30. [DOI: 10.3233/nre-151244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Colette M. Smart
- JFK-Johnson Rehabilitation Institute and the New Jersey Neuroscience Institute, JFK Medical Center, Edison, NJ, USA
- Department of Psychology, University of Victoria, Victoria, BC, Canada
| | - Joseph T. Giacino
- JFK-Johnson Rehabilitation Institute and the New Jersey Neuroscience Institute, JFK Medical Center, Edison, NJ, USA
- Department of Physical Medicine & Rehabilitation, Spaulding Rehabilitation Hospital, Boston, MA, USA
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570
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Qin P, Wu X, Huang Z, Duncan NW, Tang W, Wolff A, Hu J, Gao L, Jin Y, Wu X, Zhang J, Lu L, Wu C, Qu X, Mao Y, Weng X, Zhang J, Northoff G. How are different neural networks related to consciousness? Ann Neurol 2015; 78:594-605. [PMID: 26290126 DOI: 10.1002/ana.24479] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 07/09/2015] [Accepted: 07/09/2015] [Indexed: 12/18/2022]
Abstract
OBJECTIVE We aimed to investigate the roles of different resting-state networks in predicting both the actual level of consciousness and its recovery in brain injury patients. METHODS We investigated resting-state functional connectivity within different networks in patients with varying levels of consciousness: unresponsive wakefulness syndrome (UWS; n = 56), minimally conscious state (MCS; n = 29), and patients with brain lesions but full consciousness (BL; n = 48). Considering the actual level of consciousness, we compared the strength of network connectivity among the patient groups. We then checked the presence of connections between specific regions in individual patients and calculated the frequency of this in the different patient groups. Considering the recovery of consciousness, we split the UWS group into 2 subgroups according to recovery: those who emerged from UWS (UWS-E) and those who remained in UWS (UWS-R). The above analyses were repeated on these 2 subgroups. RESULTS Functional connectivity strength in salience network (SN), especially connectivity between the supragenual anterior cingulate cortex (SACC) and left anterior insula (LAI), was reduced in the unconscious state (UWS) compared to the conscious state (MCS and BL). Moreover, at the individual level, SACC-LAI connectivity was more present in MCS than in UWS. Default-mode network (DMN) connectivity strength, especially between the posterior cingulate cortex (PCC) and left lateral parietal cortex (LLPC), was reduced in UWS-R compared with UWS-E. Furthermore, PCC-LLPC connectivity was more present in UWS-E than in UWS-R. INTERPRETATION Our findings show that SN (SACC-LAI) connectivity correlates with behavioral signs of consciousness, whereas DMN (PCC-LLPC) connectivity instead predicts recovery of consciousness.
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Affiliation(s)
- Pengmin Qin
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan.,Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada.,Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan
| | - Xuehai Wu
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Zirui Huang
- Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada
| | - Niall W Duncan
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan.,Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada.,Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan.,Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
| | - Weijun Tang
- Radiologic Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Annemarie Wolff
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan
| | - Jin Hu
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Liang Gao
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Yi Jin
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Xing Wu
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Jianfeng Zhang
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
| | - Lu Lu
- Radiologic Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Chunping Wu
- Radiologic Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaoying Qu
- Radiologic Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Ying Mao
- Neurosurgical Department of Huashan Hospital, Fudan University, Shanghai, China
| | - Xuchu Weng
- Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China
| | - Jun Zhang
- Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai, China
| | - Georg Northoff
- Graduate Institute of Humanities in Medicine, Taipei Medical University, Taipei, Taiwan.,Institute of Mental Health Research, University of Ottawa, Ottawa, Ontario, Canada.,Brain and Consciousness Research Center, Taipei Medical University-Shuang Ho Hospital, New Taipei City, Taiwan.,Center for Cognition and Brain Disorders, Hangzhou Normal University, Hangzhou, China.,National Chengchi University Research Center for Mind, Brain, and Learning, Taipei, Taiwan
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571
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Complexity of Multi-Dimensional Spontaneous EEG Decreases during Propofol Induced General Anaesthesia. PLoS One 2015; 10:e0133532. [PMID: 26252378 PMCID: PMC4529106 DOI: 10.1371/journal.pone.0133532] [Citation(s) in RCA: 159] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 06/28/2015] [Indexed: 11/20/2022] Open
Abstract
Emerging neural theories of consciousness suggest a correlation between a specific type of neural dynamical complexity and the level of consciousness: When awake and aware, causal interactions between brain regions are both integrated (all regions are to a certain extent connected) and differentiated (there is inhomogeneity and variety in the interactions). In support of this, recent work by Casali et al (2013) has shown that Lempel-Ziv complexity correlates strongly with conscious level, when computed on the EEG response to transcranial magnetic stimulation. Here we investigated complexity of spontaneous high-density EEG data during propofol-induced general anaesthesia. We consider three distinct measures: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability in the constitution of the set of active channels; and (iii) the novel synchrony coalition entropy (SCE), which measures the variability in the constitution of the set of synchronous channels. After some simulations on Kuramoto oscillator models which demonstrate that these measures capture distinct 'flavours' of complexity, we show that there is a robustly measurable decrease in the complexity of spontaneous EEG during general anaesthesia.
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572
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Solovey G, Alonso LM, Yanagawa T, Fujii N, Magnasco MO, Cecchi GA, Proekt A. Loss of Consciousness Is Associated with Stabilization of Cortical Activity. J Neurosci 2015; 35:10866-77. [PMID: 26224868 PMCID: PMC4518057 DOI: 10.1523/jneurosci.4895-14.2015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 06/04/2015] [Accepted: 06/11/2015] [Indexed: 11/21/2022] Open
Abstract
What aspects of neuronal activity distinguish the conscious from the unconscious brain? This has been a subject of intense interest and debate since the early days of neurophysiology. However, as any practicing anesthesiologist can attest, it is currently not possible to reliably distinguish a conscious state from an unconscious one on the basis of brain activity. Here we approach this problem from the perspective of dynamical systems theory. We argue that the brain, as a dynamical system, is self-regulated at the boundary between stable and unstable regimes, allowing it in particular to maintain high susceptibility to stimuli. To test this hypothesis, we performed stability analysis of high-density electrocorticography recordings covering an entire cerebral hemisphere in monkeys during reversible loss of consciousness. We show that, during loss of consciousness, the number of eigenmodes at the edge of instability decreases smoothly, independently of the type of anesthetic and specific features of brain activity. The eigenmodes drift back toward the unstable line during recovery of consciousness. Furthermore, we show that stability is an emergent phenomenon dependent on the correlations among activity in different cortical regions rather than signals taken in isolation. These findings support the conclusion that dynamics at the edge of instability are essential for maintaining consciousness and provide a novel and principled measure that distinguishes between the conscious and the unconscious brain. SIGNIFICANCE STATEMENT What distinguishes brain activity during consciousness from that observed during unconsciousness? Answering this question has proven difficult because neither consciousness nor lack thereof have universal signatures in terms of most specific features of brain activity. For instance, different anesthetics induce different patterns of brain activity. We demonstrate that loss of consciousness is universally and reliably associated with stabilization of cortical dynamics regardless of the specific activity characteristics. To give an analogy, our analysis suggests that loss of consciousness is akin to depressing the damper pedal on the piano, which makes the sounds dissipate quicker regardless of the specific melody being played. This approach may prove useful in detecting consciousness on the basis of brain activity under anesthesia and other settings.
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Affiliation(s)
- Guillermo Solovey
- Laboratories of Mathematical Physics and Integrative Neuroscience Laboratory, Buenos Aires, Argentina, Instituto de Cálculo, Faculty of Natural Sciences, University of Buenos Aires (C1428EGA), Buenos Aires, Argentina
| | | | - Toru Yanagawa
- Laboratory for Adaptive Intelligence, Brain Science Institute, RIKEN, Saitama, 351-0198 Japan
| | - Naotaka Fujii
- Laboratory for Adaptive Intelligence, Brain Science Institute, RIKEN, Saitama, 351-0198 Japan
| | | | - Guillermo A Cecchi
- Computational Biology Center, T. J. Watson IBM Research Laboratory, Yorktown Heights, New York 10598, and
| | - Alex Proekt
- Neurobiology and Behavior, Rockefeller University, New York, New York 10065, Department of Anesthesiology, Weill Medical Center, New York, New York 10065
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573
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The 9th International Symposium on Memory and Awareness in Anesthesia (MAA9). Br J Anaesth 2015. [DOI: 10.1093/bja/aev204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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574
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Demertzi A, Antonopoulos G, Heine L, Voss HU, Crone JS, de Los Angeles C, Bahri MA, Di Perri C, Vanhaudenhuyse A, Charland-Verville V, Kronbichler M, Trinka E, Phillips C, Gomez F, Tshibanda L, Soddu A, Schiff ND, Whitfield-Gabrieli S, Laureys S. Intrinsic functional connectivity differentiates minimally conscious from unresponsive patients. Brain 2015; 138:2619-31. [PMID: 26117367 DOI: 10.1093/brain/awv169] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 04/18/2015] [Indexed: 01/28/2023] Open
Affiliation(s)
- Athena Demertzi
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
| | - Georgios Antonopoulos
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
| | - Lizette Heine
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
| | - Henning U Voss
- 2 Department of Radiology and Citigroup Biomedical Imaging Centre, Weill Cornell Medical College, New York, USA
| | - Julia Sophia Crone
- 3 Department of Psychology and Centre for Neurocognitive Research, Salzburg, Austria 4 Neuroscience Institute and Centre for Neurocognitive Research, Christian-Doppler-Klinik, Paracelsus Private Medical University, Salzburg, Austria 5 Department of Neurology, Christian-Doppler-Klinik, Paracelsus Private Medical University, Salzburg, Austria
| | - Carlo de Los Angeles
- 6 Martinos Imaging Centre at McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge MA, USA
| | | | - Carol Di Perri
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
| | - Audrey Vanhaudenhuyse
- 8 Department of Algology and Palliative Care, CHU University Hospital of Liège, Liège, Belgium
| | - Vanessa Charland-Verville
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
| | - Martin Kronbichler
- 3 Department of Psychology and Centre for Neurocognitive Research, Salzburg, Austria 4 Neuroscience Institute and Centre for Neurocognitive Research, Christian-Doppler-Klinik, Paracelsus Private Medical University, Salzburg, Austria
| | - Eugen Trinka
- 5 Department of Neurology, Christian-Doppler-Klinik, Paracelsus Private Medical University, Salzburg, Austria
| | | | - Francisco Gomez
- 9 Computer Science Department, Universidad Central de Colombia, Bogota, Colombia
| | - Luaba Tshibanda
- 10 Department of Radiology, CHU University Hospital of Liège, Liège, Belgium
| | - Andrea Soddu
- 11 Brain and Mind Institute, Department of Physics and Astronomy, Western University, London, Ontario, Canada
| | - Nicholas D Schiff
- 12 Department of Neuroscience, Weill Cornell Graduate School of Medical Sciences, New York, USA 13 Department of Neurology and Neuroscience, Weill Cornell Medical College, New York, USA
| | - Susan Whitfield-Gabrieli
- 6 Martinos Imaging Centre at McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge MA, USA
| | - Steven Laureys
- 1 Coma Science Group, GIGA-Research & Cyclotron Research Centre, University and CHU University Hospital of Liège, Liège, Belgium
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575
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Cornelissen L, Kim SE, Purdon PL, Brown EN, Berde CB. Age-dependent electroencephalogram (EEG) patterns during sevoflurane general anesthesia in infants. eLife 2015; 4:e06513. [PMID: 26102526 PMCID: PMC4502759 DOI: 10.7554/elife.06513] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 06/22/2015] [Indexed: 12/31/2022] Open
Abstract
Electroencephalogram (EEG) approaches may provide important information about developmental changes in brain-state dynamics during general anesthesia. We used multi-electrode EEG, analyzed with multitaper spectral methods and video recording of body movement to characterize the spatio-temporal dynamics of brain activity in 36 infants 0-6 months old when awake, and during maintenance of and emergence from sevoflurane general anesthesia. During maintenance: (1) slow-delta oscillations were present in all ages; (2) theta and alpha oscillations emerged around 4 months; (3) unlike adults, all infants lacked frontal alpha predominance and coherence. Alpha power was greatest during maintenance, compared to awake and emergence in infants at 4-6 months. During emergence, theta and alpha power decreased with decreasing sevoflurane concentration in infants at 4-6 months. These EEG dynamic differences are likely due to developmental factors including regional differences in synaptogenesis, glucose metabolism, and myelination across the cortex. We demonstrate the need to apply age-adjusted analytic approaches to develop neurophysiologic-based strategies for pediatric anesthetic state monitoring.
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Affiliation(s)
- Laura Cornelissen
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, United States
| | - Seong-Eun Kim
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Patrick L Purdon
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Boston, United States
| | - Emery N Brown
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, United States
| | - Charles B Berde
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, United States
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576
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Deco G, Tononi G, Boly M, Kringelbach ML. Rethinking segregation and integration: contributions of whole-brain modelling. Nat Rev Neurosci 2015; 16:430-9. [DOI: 10.1038/nrn3963] [Citation(s) in RCA: 369] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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577
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Gallimore AR. Restructuring consciousness -the psychedelic state in light of integrated information theory. Front Hum Neurosci 2015; 9:346. [PMID: 26124719 PMCID: PMC4464176 DOI: 10.3389/fnhum.2015.00346] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 05/29/2015] [Indexed: 11/13/2022] Open
Abstract
The psychological state elicited by the classic psychedelics drugs, such as LSD and psilocybin, is one of the most fascinating and yet least understood states of consciousness. However, with the advent of modern functional neuroimaging techniques, the effect of these drugs on neural activity is now being revealed, although many of the varied phenomenological features of the psychedelic state remain challenging to explain. Integrated information theory (IIT) is one of the foremost contemporary theories of consciousness, providing a mathematical formalization of both the quantity and quality of conscious experience. This theory can be applied to all known states of consciousness, including the psychedelic state. Using the results of functional neuroimaging data on the psychedelic state, the effects of psychedelic drugs on both the level and structure of consciousness can be explained in terms of the conceptual framework of IIT. This new IIT-based model of the psychedelic state provides an explanation for many of its phenomenological features, including unconstrained cognition, alterations in the structure and meaning of concepts and a sense of expanded awareness. This model also suggests that whilst cognitive flexibility, creativity, and imagination are enhanced during the psychedelic state, this occurs at the expense of cause-effect information, as well as degrading the brain's ability to organize, categorize, and differentiate the constituents of conscious experience. Furthermore, the model generates specific predictions that can be tested using a combination of functional imaging techniques, as has been applied to the study of levels of consciousness during anesthesia and following brain injury.
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Affiliation(s)
- Andrew R Gallimore
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University Okinawa, Japan
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578
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Tu S, Jou J, Cui Q, Zhao G, Wang K, Hitchman G, Qiu J, Zhang Q. Category-selective attention interacts with partial awareness processes in a continuous manner: An fMRI study. COGENT PSYCHOLOGY 2015. [DOI: 10.1080/23311908.2015.1046243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- Shen Tu
- Department of Psychology, Institute of Education, China West Normal University, Nanchong, China
| | - Jerwen Jou
- Department of Psychology, University of Texas – Pan American, Edinburg, TX 78539, USA
| | - Qian Cui
- School of Political Science and Public Administration, University of Electronic Science and Technology of China, Chengdu, China
| | - Guang Zhao
- School of Psychology, Liaoning Normal University, Dalian, China
| | - Kangcheng Wang
- Faculty of Psychology, Southwest University, Chongqing, China
- Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Glenn Hitchman
- Faculty of Psychology, Southwest University, Chongqing, China
- Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Jiang Qiu
- Faculty of Psychology, Southwest University, Chongqing, China
- Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
| | - Qinglin Zhang
- Faculty of Psychology, Southwest University, Chongqing, China
- Key Laboratory of Cognition and Personality, Ministry of Education, Chongqing, China
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579
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Boly M, Sasai S, Gosseries O, Oizumi M, Casali A, Massimini M, Tononi G. Stimulus set meaningfulness and neurophysiological differentiation: a functional magnetic resonance imaging study. PLoS One 2015; 10:e0125337. [PMID: 25970444 PMCID: PMC4430458 DOI: 10.1371/journal.pone.0125337] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 03/11/2015] [Indexed: 11/19/2022] Open
Abstract
A meaningful set of stimuli, such as a sequence of frames from a movie, triggers a set of different experiences. By contrast, a meaningless set of stimuli, such as a sequence of ‘TV noise’ frames, triggers always the same experience—of seeing ‘TV noise’—even though the stimuli themselves are as different from each other as the movie frames. We reasoned that the differentiation of cortical responses underlying the subject’s experiences, as measured by Lempel-Ziv complexity (incompressibility) of functional MRI images, should reflect the overall meaningfulness of a set of stimuli for the subject, rather than differences among the stimuli. We tested this hypothesis by quantifying the differentiation of brain activity patterns in response to a movie sequence, to the same movie scrambled in time, and to ‘TV noise’, where the pixels from each movie frame were scrambled in space. While overall cortical activation was strong and widespread in all conditions, the differentiation (Lempel-Ziv complexity) of brain activation patterns was correlated with the meaningfulness of the stimulus set, being highest in the movie condition, intermediate in the scrambled movie condition, and minimal for ‘TV noise’. Stimulus set meaningfulness was also associated with higher information integration among cortical regions. These results suggest that the differentiation of neural responses can be used to assess the meaningfulness of a given set of stimuli for a given subject, without the need to identify the features and categories that are relevant to the subject, nor the precise location of selective neural responses.
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Affiliation(s)
- Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, Wisconsin, United States of America
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (MB); (GT)
| | - Shuntaro Sasai
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America
| | - Olivia Gosseries
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America
- Coma Science Group, Cyclotron Research Centre and Department of Neurology, University of Liege and CHU Sart Tilman Hospital, Liege, Belgium
| | - Masafumi Oizumi
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America
- Riken Brain Science Institute, Tokyo, Japan
| | - Adenauer Casali
- Department of Biomedical and Clinical Sciences ‘Luigi Sacco’, University of Milan, Milan, Italy
| | - Marcello Massimini
- Department of Biomedical and Clinical Sciences ‘Luigi Sacco’, University of Milan, Milan, Italy
- Instituto Di Ricovero e Cura a Carattere Scientifico, Fondazione Don Carlo Gnocchi, Milan, Italy
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, Wisconsin, United States of America
- * E-mail: (MB); (GT)
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580
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Pal D, Hambrecht-Wiedbusch VS, Silverstein BH, Mashour GA. Electroencephalographic coherence and cortical acetylcholine during ketamine-induced unconsciousness. Br J Anaesth 2015; 114:979-89. [PMID: 25951831 DOI: 10.1093/bja/aev095] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/22/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND There is limited understanding of cortical neurochemistry and cortical connectivity during ketamine anaesthesia. We conducted a systematic study to investigate the effects of ketamine on cortical acetylcholine (ACh) and electroencephalographic coherence. METHODS Male Sprague-Dawley rats (n=11) were implanted with electrodes to record electroencephalogram (EEG) from frontal, parietal, and occipital cortices, and with a microdialysis guide cannula for simultaneous measurement of ACh concentrations in prefrontal cortex before, during, and after ketamine anaesthesia. Coherence and power spectral density computed from the EEG, and ACh concentrations, were compared between conscious and unconscious states. Loss of righting reflex was used as a surrogate for unconsciousness. RESULTS Ketamine-induced unconsciousness was associated with a global reduction of power (P=0.02) in higher gamma bandwidths (>65 Hz), a global reduction of coherence (P≤0.01) across a broad frequency range (0.5-250 Hz), and a significant increase in ACh concentrations (P=0.01) in the prefrontal cortex. Compared with the unconscious state, recovery of righting reflex was marked by a further increase in ACh concentrations (P=0.0007), global increases in power in theta (4-10 Hz; P=0.03) and low gamma frequencies (25-55 Hz; P=0.0001), and increase in power (P≤0.01) and coherence (P≤0.002) in higher gamma frequencies (65-250 Hz). Acetylcholine concentrations, coherence, and spectral properties returned to baseline levels after a prolonged recovery period. CONCLUSIONS Ketamine-induced unconsciousness is characterized by suppression of high-frequency gamma activity and a breakdown of cortical coherence, despite increased cholinergic tone in the cortex.
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Affiliation(s)
- D Pal
- Department of Anesthesiology, University of Michigan, 7433 Medical Science Building I, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5615, USA Center for Consciousness Science, University of Michigan, Ann Arbor, MI 48109, USA
| | - V S Hambrecht-Wiedbusch
- Department of Anesthesiology, University of Michigan, 7433 Medical Science Building I, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5615, USA Center for Consciousness Science, University of Michigan, Ann Arbor, MI 48109, USA
| | - B H Silverstein
- Department of Anesthesiology, University of Michigan, 7433 Medical Science Building I, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5615, USA
| | - G A Mashour
- Department of Anesthesiology, University of Michigan, 7433 Medical Science Building I, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5615, USA Center for Consciousness Science, University of Michigan, Ann Arbor, MI 48109, USA Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
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581
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Cortical activity is more stable when sensory stimuli are consciously perceived. Proc Natl Acad Sci U S A 2015; 112:E2083-92. [PMID: 25847997 DOI: 10.1073/pnas.1418730112] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
According to recent evidence, stimulus-tuned neurons in the cerebral cortex exhibit reduced variability in firing rate across trials, after the onset of a stimulus. However, in order for a reduction in variability to be directly relevant to perception and behavior, it must be realized within trial--the pattern of activity must be relatively stable. Stability is characteristic of decision states in recurrent attractor networks, and its possible relevance to conscious perception has been suggested by theorists. However, it is difficult to measure on the within-trial time scales and broadly distributed spatial scales relevant to perception. We recorded simultaneous magneto- and electroencephalography (MEG and EEG) data while subjects observed threshold-level visual stimuli. Pattern-similarity analyses applied to the data from MEG gradiometers uncovered a pronounced decrease in variability across trials after stimulus onset, consistent with previous single-unit data. This was followed by a significant divergence in variability depending upon subjective report (seen/unseen), with seen trials exhibiting less variability. Applying the same analysis across time, within trial, we found that the latter effect coincided in time with a difference in the stability of the pattern of activity. Stability alone could be used to classify data from individual trials as "seen" or "unseen." The same metric applied to EEG data from patients with disorders of consciousness exposed to auditory stimuli diverged parametrically according to clinically diagnosed level of consciousness. Differences in signal strength could not account for these results. Conscious perception may involve the transient stabilization of distributed cortical networks, corresponding to a global brain-scale decision.
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582
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Fabbro F, Aglioti SM, Bergamasco M, Clarici A, Panksepp J. Evolutionary aspects of self- and world consciousness in vertebrates. Front Hum Neurosci 2015; 9:157. [PMID: 25859205 PMCID: PMC4374625 DOI: 10.3389/fnhum.2015.00157] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 03/07/2015] [Indexed: 12/16/2022] Open
Abstract
Although most aspects of world and self-consciousness are inherently subjective, neuroscience studies in humans and non-human animals provide correlational and causative indices of specific links between brain activity and representation of the self and the world. In this article we review neuroanatomic, neurophysiological and neuropsychological data supporting the hypothesis that different levels of self and world representation in vertebrates rely upon (i) a “basal” subcortical system that includes brainstem, hypothalamus and central thalamic nuclei and that may underpin the primary (or anoetic) consciousness likely present in all vertebrates; and (ii) a forebrain system that include the medial and lateral structures of the cerebral hemispheres and may sustain the most sophisticated forms of consciousness [e.g., noetic (knowledge based) and autonoetic, reflective knowledge]. We posit a mutual, bidirectional functional influence between these two major brain circuits. We conclude that basic aspects of consciousness like primary self and core self (based on anoetic and noetic consciousness) are present in many species of vertebrates and that, even self-consciousness (autonoetic consciousness) does not seem to be a prerogative of humans and of some non-human primates but may, to a certain extent, be present in some other mammals and birds
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Affiliation(s)
- Franco Fabbro
- Department of Human Sciences, University of Udine Udine, Italy ; Perceptual Robotics Laboratory, Scuola Superiore Sant'Anna Pisa, Italy
| | - Salvatore M Aglioti
- Department of Psychology, Sapienza University of Rome Rome, Italy ; Fondazione Santa Lucia, IRCCS Rome, Italy
| | | | - Andrea Clarici
- Psychiatric Unit, Department of Medical, Surgical and Health Sciences, University of Trieste Trieste, Italy
| | - Jaak Panksepp
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, College of Veterinary Medicine, Washington State University Pullman, WA, USA
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583
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Blume C, Del Giudice R, Wislowska M, Lechinger J, Schabus M. Across the consciousness continuum-from unresponsive wakefulness to sleep. Front Hum Neurosci 2015; 9:105. [PMID: 25805982 PMCID: PMC4354375 DOI: 10.3389/fnhum.2015.00105] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 02/12/2015] [Indexed: 11/13/2022] Open
Abstract
Advances in the development of new paradigms as well as in neuroimaging techniques nowadays enable us to make inferences about the level of consciousness patients with disorders of consciousness (DOC) retain. They, moreover, allow to predict their probable development. Today, we know that certain brain responses (e.g., event-related potentials or oscillatory changes) to stimulation, circadian rhythmicity, the presence or absence of sleep patterns as well as measures of resting state brain activity can serve the diagnostic and prognostic evaluation process. Still, the paradigms we are using nowadays do not allow to disentangle VS/UWS and minimally conscious state (MCS) patients with the desired reliability and validity. Furthermore, even rather well-established methods have, unfortunately, not found their way into clinical routine yet. We here review current literature as well as recent findings from our group and discuss how neuroimaging methods (fMRI, PET) and particularly electroencephalography (EEG) can be used to investigate cognition in DOC or even to assess the degree of residual awareness. We, moreover, propose that circadian rhythmicity and sleep in brain-injured patients are promising fields of research in this context.
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Affiliation(s)
- Christine Blume
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg Salzburg, Austria ; Centre for Cognitive Neuroscience Salzburg (CCNS), University of Salzburg Salzburg, Austria
| | - Renata Del Giudice
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg Salzburg, Austria ; Centre for Cognitive Neuroscience Salzburg (CCNS), University of Salzburg Salzburg, Austria
| | - Malgorzata Wislowska
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg Salzburg, Austria
| | - Julia Lechinger
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg Salzburg, Austria ; Centre for Cognitive Neuroscience Salzburg (CCNS), University of Salzburg Salzburg, Austria
| | - Manuel Schabus
- Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, University of Salzburg Salzburg, Austria ; Centre for Cognitive Neuroscience Salzburg (CCNS), University of Salzburg Salzburg, Austria
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584
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Bistability breaks-off deterministic responses to intracortical stimulation during non-REM sleep. Neuroimage 2015; 112:105-113. [PMID: 25747918 DOI: 10.1016/j.neuroimage.2015.02.056] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 02/09/2015] [Accepted: 02/24/2015] [Indexed: 12/21/2022] Open
Abstract
During non-rapid eye movement (NREM) sleep (stage N3), when consciousness fades, cortico-cortical interactions are impaired while neurons are still active and reactive. Why is this? We compared cortico-cortical evoked-potentials recorded during wakefulness and NREM by means of time-frequency analysis and phase-locking measures in 8 epileptic patients undergoing intra-cerebral stimulations/recordings for clinical evaluation. We observed that, while during wakefulness electrical stimulation triggers a chain of deterministic phase-locked activations in its cortical targets, during NREM the same input induces a slow wave associated with an OFF-period (suppression of power>20Hz), possibly reflecting a neuronal down-state. Crucially, after the OFF-period, cortical activity resumes to wakefulness-like levels, but the deterministic effects of the initial input are lost, as indicated by a sharp drop of phase-locked activity. These findings suggest that the intrinsic tendency of cortical neurons to fall into a down-state after a transient activation (i.e. bistability) prevents the emergence of stable patterns of causal interactions among cortical areas during NREM. Besides sleep, the same basic neurophysiological dynamics may play a role in pathological conditions in which thalamo-cortical information integration and consciousness are impaired in spite of preserved neuronal activity.
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585
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586
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Abásolo D, Simons S, Morgado da Silva R, Tononi G, Vyazovskiy VV. Lempel-Ziv complexity of cortical activity during sleep and waking in rats. J Neurophysiol 2015; 113:2742-52. [PMID: 25717159 PMCID: PMC4416627 DOI: 10.1152/jn.00575.2014] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 02/23/2015] [Indexed: 01/01/2023] Open
Abstract
Understanding the dynamics of brain activity manifested in the EEG, local field potentials (LFP), and neuronal spiking is essential for explaining their underlying mechanisms and physiological significance. Much has been learned about sleep regulation using conventional EEG power spectrum, coherence, and period-amplitude analyses, which focus primarily on frequency and amplitude characteristics of the signals and on their spatio-temporal synchronicity. However, little is known about the effects of ongoing brain state or preceding sleep-wake history on the nonlinear dynamics of brain activity. Recent advances in developing novel mathematical approaches for investigating temporal structure of brain activity based on such measures, as Lempel-Ziv complexity (LZC) can provide insights that go beyond those obtained with conventional techniques of signal analysis. Here, we used extensive data sets obtained in spontaneously awake and sleeping adult male laboratory rats, as well as during and after sleep deprivation, to perform a detailed analysis of cortical LFP and neuronal activity with LZC approach. We found that activated brain states—waking and rapid eye movement (REM) sleep are characterized by higher LZC compared with non-rapid eye movement (NREM) sleep. Notably, LZC values derived from the LFP were especially low during early NREM sleep after sleep deprivation and toward the middle of individual NREM sleep episodes. We conclude that LZC is an important and yet largely unexplored measure with a high potential for investigating neurophysiological mechanisms of brain activity in health and disease.
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Affiliation(s)
- Daniel Abásolo
- Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, Faculty of Engineering and Physical Sciences (J5), University of Surrey, Guildford, United Kingdom
| | - Samantha Simons
- Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, Faculty of Engineering and Physical Sciences (J5), University of Surrey, Guildford, United Kingdom
| | - Rita Morgado da Silva
- Centre for Biomedical Engineering, Department of Mechanical Engineering Sciences, Faculty of Engineering and Physical Sciences (J5), University of Surrey, Guildford, United Kingdom
| | - Giulio Tononi
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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587
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Porta A, Baumert M, Cysarz D, Wessel N. Enhancing dynamical signatures of complex systems through symbolic computation. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0099. [PMID: 25548265 PMCID: PMC4281870 DOI: 10.1098/rsta.2014.0099] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Affiliation(s)
- Alberto Porta
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy IRCCS Galeazzi Orthopedic Institute, Milan, Italy
| | - Mathias Baumert
- School of Electrical and Electronic Engineering, University of Adelaide, Adelaide, South Australia, Australia
| | - Dirk Cysarz
- Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Witten, Germany Institute of Integrative Medicine, University of Witten/Herdecke, Witten, Germany
| | - Niels Wessel
- Department of Physics, Humboldt-Universität zu Berlin, Berlin, Germany
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588
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Lee U, Blain-Moraes S, Mashour GA. Assessing levels of consciousness with symbolic analysis. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2015; 373:rsta.2014.0117. [PMID: 25548273 PMCID: PMC7398453 DOI: 10.1098/rsta.2014.0117] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
'Covert consciousness' is a state in which consciousness is present without the capacity for behavioural response, and it can occur in patients with intraoperative awareness or unresponsive wakefulness syndrome. To detect and prevent this undesirable state, it is critical to develop a reliable neurobiological assessment of an individual's level of consciousness that is independent of behaviour. One such approach that shows potential is measuring surrogates of cortical communication in the brain using electroencephalography (EEG). EEG is practicable in clinical application, but involves many fundamental signal processing problems, including signal-to-noise ratio and high dimensional complexity. Symbolic analysis of EEG can mitigate these problems, improving the measurement of brain connectivity and the ability to successfully assess levels of consciousness. In this article, we review the problem of covert consciousness, basic neurobiological principles of consciousness, current methods of measuring brain connectivity and the advantages of symbolic processing, with a focus on symbolic transfer entropy (STE). Finally, we discuss recent advances and clinical applications of STE and other symbolic analyses to assess levels of consciousness.
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Affiliation(s)
- UnCheol Lee
- Center for Consciousness Science, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48105, USA
| | - Stefanie Blain-Moraes
- Department of Anesthesiology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48105, USA
| | - George A Mashour
- Center for Consciousness Science, Department of Anesthesiology, Neuroscience Graduate Program, University of Michigan Medical School, 1500 East Medical Center Drive, Ann Arbor, MI 48109-5048, USA
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589
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Luauté J, Morlet D, Mattout J. BCI in patients with disorders of consciousness: Clinical perspectives. Ann Phys Rehabil Med 2015; 58:29-34. [DOI: 10.1016/j.rehab.2014.09.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 09/07/2014] [Indexed: 11/29/2022]
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590
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Anesthesia and neuroimaging: investigating the neural correlates of unconsciousness. Trends Cogn Sci 2015; 19:100-7. [DOI: 10.1016/j.tics.2014.12.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 12/03/2014] [Accepted: 12/08/2014] [Indexed: 01/18/2023]
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591
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Abstract
At rest, the brain is traversed by spontaneous functional connectivity patterns. Two hypotheses have been proposed for their origins: they may reflect a continuous stream of ongoing cognitive processes as well as random fluctuations shaped by a fixed anatomical connectivity matrix. Here we show that both sources contribute to the shaping of resting-state networks, yet with distinct contributions during consciousness and anesthesia. We measured dynamical functional connectivity with functional MRI during the resting state in awake and anesthetized monkeys. Under anesthesia, the more frequent functional connectivity patterns inherit the structure of anatomical connectivity, exhibit fewer small-world properties, and lack negative correlations. Conversely, wakefulness is characterized by the sequential exploration of a richer repertoire of functional configurations, often dissimilar to anatomical structure, and comprising positive and negative correlations among brain regions. These results reconcile theories of consciousness with observations of long-range correlation in the anesthetized brain and show that a rich functional dynamics might constitute a signature of consciousness, with potential clinical implications for the detection of awareness in anesthesia and brain-lesioned patients.
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592
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Ziemann U, Reis J, Schwenkreis P, Rosanova M, Strafella A, Badawy R, Müller-Dahlhaus F. TMS and drugs revisited 2014. Clin Neurophysiol 2014; 126:1847-68. [PMID: 25534482 DOI: 10.1016/j.clinph.2014.08.028] [Citation(s) in RCA: 476] [Impact Index Per Article: 47.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Revised: 08/03/2014] [Accepted: 08/24/2014] [Indexed: 12/18/2022]
Abstract
The combination of pharmacology and transcranial magnetic stimulation to study the effects of drugs on TMS-evoked EMG responses (pharmaco-TMS-EMG) has considerably improved our understanding of the effects of TMS on the human brain. Ten years have elapsed since an influential review on this topic has been published in this journal (Ziemann, 2004). Since then, several major developments have taken place: TMS has been combined with EEG to measure TMS evoked responses directly from brain activity rather than by motor evoked potentials in a muscle, and pharmacological characterization of the TMS-evoked EEG potentials, although still in its infancy, has started (pharmaco-TMS-EEG). Furthermore, the knowledge from pharmaco-TMS-EMG that has been primarily obtained in healthy subjects is now applied to clinical settings, for instance, to monitor or even predict clinical drug responses in neurological or psychiatric patients. Finally, pharmaco-TMS-EMG has been applied to understand the effects of CNS active drugs on non-invasive brain stimulation induced long-term potentiation-like and long-term depression-like plasticity. This is a new field that may help to develop rationales of pharmacological treatment for enhancement of recovery and re-learning after CNS lesions. This up-dated review will highlight important knowledge and recent advances in the contribution of pharmaco-TMS-EMG and pharmaco-TMS-EEG to our understanding of normal and dysfunctional excitability, connectivity and plasticity of the human brain.
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Affiliation(s)
- Ulf Ziemann
- Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University Tübingen, Tübingen, Germany.
| | - Janine Reis
- Department of Neurology, Albert-Ludwigs-University Freiburg, Freiburg, Germany
| | - Peter Schwenkreis
- Department of Neurology, BG-University Hospital Bergmannsheil Bochum, Bochum, Germany
| | - Mario Rosanova
- Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Milan, Italy; Fondazione Europea di Ricerca Biomedica, FERB Onlus, Milan, Italy
| | - Antonio Strafella
- Morton and Gloria Shulman Movement Disorder Unit & E.J. Safra Parkinson Disease Program, Toronto Western Hospital, UHN, University of Toronto, Ontario, Canada; Research Imaging Centre, Centre for Addiction and Mental Health, University of Toronto, Ontario, Canada
| | - Radwa Badawy
- Department of Neurology, Saint Vincent's Hospital, Fitzroy, The University of Melbourne, Parkville, Victoria, Australia; Department of Medicine, The University of Melbourne, Parkville, Victoria, Australia
| | - Florian Müller-Dahlhaus
- Department of Neurology & Stroke, and Hertie Institute for Clinical Brain Research, Eberhard-Karls-University Tübingen, Tübingen, Germany
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593
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Liberati G, Hünefeldt T, Olivetti Belardinelli M. Questioning the dichotomy between vegetative state and minimally conscious state: a review of the statistical evidence. Front Hum Neurosci 2014; 8:865. [PMID: 25404905 PMCID: PMC4217390 DOI: 10.3389/fnhum.2014.00865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 10/07/2014] [Indexed: 01/24/2023] Open
Abstract
Given the enormous consequences that the diagnosis of vegetative state (VS) vs. minimally conscious state (MCS) may have for the treatment of patients with disorders of consciousness, it is particularly important to empirically legitimate the distinction between these two discrete levels of consciousness. Therefore, the aim of this contribution is to review all the articles reporting statistical evidence concerning the performance of patients in VS vs. patients in MCS, on behavioral or neurophysiological measures. Twenty-three articles matched these inclusion criteria, and comprised behavioral, electroencephalographic (EEG), positron emission tomography (PET) and magnetic resonance imaging (MRI) measures. The analysis of these articles yielded 47 different statistical findings. More than half of these findings (n = 24) did not reveal any statistically significant difference between VS and MCS. Overall, there was no combination of variables that allowed reliably discriminating between VS and MCS. This pattern of results casts doubt on the empirical validity of the distinction between VS and MCS.
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Affiliation(s)
- Giulia Liberati
- Institute of Neuroscience, Université Catholique de Louvain Brussels, Belgium
| | - Thomas Hünefeldt
- ECONA - Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, "Sapienza" University of Rome Rome, Italy ; Department of Philosophy, Catholic University of Eichstätt-Ingolstadt Eichstätt, Germany
| | - Marta Olivetti Belardinelli
- ECONA - Interuniversity Centre for Research on Cognitive Processing in Natural and Artificial Systems, "Sapienza" University of Rome Rome, Italy ; Department of Psychology, Sapienza, University of Rome Rome, Italy
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594
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Block N, Carmel D, Fleming SM, Kentridge RW, Koch C, Lamme VA, Lau H, Rosenthal D. Consciousness science: real progress and lingering misconceptions. Trends Cogn Sci 2014; 18:556-7. [DOI: 10.1016/j.tics.2014.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 09/10/2014] [Indexed: 11/26/2022]
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595
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Forgacs PB, Conte MM, Fridman EA, Voss HU, Victor JD, Schiff ND. Preservation of electroencephalographic organization in patients with impaired consciousness and imaging-based evidence of command-following. Ann Neurol 2014; 76:869-79. [PMID: 25270034 DOI: 10.1002/ana.24283] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 09/30/2014] [Accepted: 09/30/2014] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Standard clinical characterization of patients with disorders of consciousness (DOC) relies on observation of motor output and may therefore lead to the misdiagnosis of vegetative state or minimally conscious state in patients with preserved cognition. We used conventional electroencephalographic (EEG) measures to assess a cohort of DOC patients with and without functional magnetic resonance imaging (fMRI)-based evidence of command-following, and correlated the findings with standard clinical behavioral evaluation and brain metabolic activity. METHODS We enrolled 44 patients with severe brain injury. Behavioral diagnosis was established using standardized clinical assessments. Long-term EEG recordings were analyzed to determine wakeful background organization and presence of elements of sleep architecture. A subset of patients had fMRI testing of command-following using motor imagery paradigms (26 patients) and resting brain metabolism measurement using (18) fluorodeoxyglucose positron emission tomography (31 patients). RESULTS All 4 patients with fMRI evidence of covert command-following consistently demonstrated well-organized EEG background during wakefulness, spindling activity during sleep, and relative preservation of cortical metabolic activity. In the entire cohort, EEG organization and overall brain metabolism showed no significant association with bedside behavioral testing, except in a few cases when EEG was severely abnormal. INTERPRETATION These findings suggest that conventional EEG is a simple strategy that complements behavioral and imaging characterization of DOC patients. Preservation of specific EEG features may be used to assess the likelihood of unrecognized cognitive abilities in severely brain-injured patients with very limited or no motor responses.
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Affiliation(s)
- Peter B Forgacs
- The Rockefeller University, Weill Cornell Medical College, New York, NY; Feil Family Brain and Mind Research Institute, Department of Neurology, Weill Cornell Medical College, New York, NY
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596
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Chennu S, Finoia P, Kamau E, Allanson J, Williams GB, Monti MM, Noreika V, Arnatkeviciute A, Canales-Johnson A, Olivares F, Cabezas-Soto D, Menon DK, Pickard JD, Owen AM, Bekinschtein TA. Spectral signatures of reorganised brain networks in disorders of consciousness. PLoS Comput Biol 2014; 10:e1003887. [PMID: 25329398 PMCID: PMC4199497 DOI: 10.1371/journal.pcbi.1003887] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 08/26/2014] [Indexed: 12/17/2022] Open
Abstract
Theoretical advances in the science of consciousness have proposed that it is concomitant with balanced cortical integration and differentiation, enabled by efficient networks of information transfer across multiple scales. Here, we apply graph theory to compare key signatures of such networks in high-density electroencephalographic data from 32 patients with chronic disorders of consciousness, against normative data from healthy controls. Based on connectivity within canonical frequency bands, we found that patient networks had reduced local and global efficiency, and fewer hubs in the alpha band. We devised a novel topographical metric, termed modular span, which showed that the alpha network modules in patients were also spatially circumscribed, lacking the structured long-distance interactions commonly observed in the healthy controls. Importantly however, these differences between graph-theoretic metrics were partially reversed in delta and theta band networks, which were also significantly more similar to each other in patients than controls. Going further, we found that metrics of alpha network efficiency also correlated with the degree of behavioural awareness. Intriguingly, some patients in behaviourally unresponsive vegetative states who demonstrated evidence of covert awareness with functional neuroimaging stood out from this trend: they had alpha networks that were remarkably well preserved and similar to those observed in the controls. Taken together, our findings inform current understanding of disorders of consciousness by highlighting the distinctive brain networks that characterise them. In the significant minority of vegetative patients who follow commands in neuroimaging tests, they point to putative network mechanisms that could support cognitive function and consciousness despite profound behavioural impairment.
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Affiliation(s)
- Srivas Chennu
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
- * E-mail:
| | - Paola Finoia
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
| | - Evelyn Kamau
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Judith Allanson
- Cambridge University Hospitals NHS Foundation Trust, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Guy B. Williams
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Martin M. Monti
- Department of Psychology, University of California at Los Angeles, Los Angeles, California, United States of America
| | - Valdas Noreika
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
| | - Aurina Arnatkeviciute
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
| | - Andrés Canales-Johnson
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
- Laboratory of Cognitive and Social Neuroscience, Universidad Diego Portales, Santiago, Chile
| | - Francisco Olivares
- Laboratory of Cognitive and Social Neuroscience, Universidad Diego Portales, Santiago, Chile
| | - Daniela Cabezas-Soto
- Laboratory of Cognitive and Social Neuroscience, Universidad Diego Portales, Santiago, Chile
| | - David K. Menon
- Division of Anaesthesia, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - John D. Pickard
- Department of Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, United Kingdom
| | - Adrian M. Owen
- The Brain and Mind Institute, Natural Sciences Centre, The University of Western Ontario, London, Ontario, Canada
| | - Tristan A. Bekinschtein
- Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, United Kingdom
- Department of Psychology, University of Cambridge, Cambridge, United Kingdom
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597
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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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598
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A common neural code for similar conscious experiences in different individuals. Proc Natl Acad Sci U S A 2014; 111:14277-82. [PMID: 25225384 DOI: 10.1073/pnas.1407007111] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The interpretation of human consciousness from brain activity, without recourse to speech or action, is one of the most provoking and challenging frontiers of modern neuroscience. We asked whether there is a common neural code that underpins similar conscious experiences, which could be used to decode these experiences in the absence of behavior. To this end, we used richly evocative stimulation (an engaging movie) portraying real-world events to elicit a similar conscious experience in different people. Common neural correlates of conscious experience were quantified and related to measurable, quantitative and qualitative, executive components of the movie through two additional behavioral investigations. The movie's executive demands drove synchronized brain activity across healthy participants' frontal and parietal cortices in regions known to support executive function. Moreover, the timing of activity in these regions was predicted by participants' highly similar qualitative experience of the movie's moment-to-moment executive demands, suggesting that synchronization of activity across participants underpinned their similar experience. Thus we demonstrate, for the first time to our knowledge, that a neural index based on executive function reliably predicted every healthy individual's similar conscious experience in response to real-world events unfolding over time. This approach provided strong evidence for the conscious experience of a brain-injured patient, who had remained entirely behaviorally nonresponsive for 16 y. The patient's executive engagement and moment-to-moment perception of the movie content were highly similar to that of every healthy participant. These findings shed light on the common basis of human consciousness and enable the interpretation of conscious experience in the absence of behavior.
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599
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Abbate C, Trimarchi PD, Basile I, Mazzucchi A, Devalle G. Sensory stimulation for patients with disorders of consciousness: from stimulation to rehabilitation. Front Hum Neurosci 2014; 8:616. [PMID: 25157226 PMCID: PMC4127462 DOI: 10.3389/fnhum.2014.00616] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 07/23/2014] [Indexed: 11/05/2022] Open
Affiliation(s)
- Carlo Abbate
- Unità Operativa Complessa di Geriatria, Fondazione I.R.C.C.S. Ca' Granda, Ospedale Maggiore Policlinico Milan, Italy
| | - Pietro D Trimarchi
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Isabella Basile
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Anna Mazzucchi
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
| | - Guya Devalle
- Nucleo di Accoglienza per Persone in Stato Vegetativo, Fondazione I.R.C.C.S. Don Carlo Gnocchi ONLUS, Milan, Italy
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600
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Affiliation(s)
- Jamie Sleigh
- Department of Anaesthesia, University of Auckland, Waikato Hospital, Hamilton 3240, New Zealand.
| | - Catherine E Warnaby
- Oxford Centre for Functional MRI of the Brain, University of Oxford, John Radcliffe Hospital, Oxford, UK
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