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Rokos A, Mah R, Boshra R, Harrison A, Choy TL, Blain-Moraes S, Connolly JF. Eliciting and Recording Event Related Potentials (ERPs) in Behaviourally Unresponsive Populations: A Retrospective Commentary on Critical Factors. Brain Sci 2021; 11:835. [PMID: 34202435 DOI: 10.3390/brainsci11070835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/19/2021] [Accepted: 06/19/2021] [Indexed: 12/05/2022] Open
Abstract
A consistent limitation when designing event-related potential paradigms and interpreting results is a lack of consideration of the multivariate factors that affect their elicitation and detection in behaviorally unresponsive individuals. This paper provides a retrospective commentary on three factors that influence the presence and morphology of long-latency event-related potentials—the P3b and N400. We analyze event-related potentials derived from electroencephalographic (EEG) data collected from small groups of healthy youth and healthy elderly to illustrate the effect of paradigm strength and subject age; we analyze ERPs collected from an individual with severe traumatic brain injury to illustrate the effect of stimulus presentation speed. Based on these critical factors, we support that: (1) the strongest paradigms should be used to elicit event-related potentials in unresponsive populations; (2) interpretation of event-related potential results should account for participant age; and (3) speed of stimulus presentation should be slower in unresponsive individuals. The application of these practices when eliciting and recording event-related potentials in unresponsive individuals will help to minimize result interpretation ambiguity, increase confidence in conclusions, and advance the understanding of the relationship between long-latency event-related potentials and states of consciousness.
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Abstract
In the ongoing research of the functions of consciousness, special emphasis has been put on integration of information: the ability to combine different signals into a coherent, unified one. Several theories of consciousness hold that this ability depends on - or at least goes hand in hand with - conscious processing. Yet some empirical findings have suggested otherwise, claiming that integration of information could take place even without awareness. Trying to reconcile this apparent contradiction, the "windows of integration" (WOI) hypothesis claims that conscious access enables signal processing over large integration windows. The hypothesis applies to integration windows defined either temporally, spatially, or semantically. In this review, we explain the hypothesis and re-examine it in light of new studies published since it was suggested. In line with the hypothesis, these studies provide compelling evidence for unconscious integration, but also demonstrate its limits with respect to time, space, and semantic distance. The review further highlights open questions that still need to be pursued to demonstrate the applicability of the WOI hypothesis as a guiding principle for understanding the depth and scope of unconscious processes.
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Affiliation(s)
- Rony Hirschhorn
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
| | - Ofer Kahane
- School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Inbal Gur-Arie
- School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Nathan Faivre
- Laboratoire de Psychologie et Neurocognition (LPNC), CNRS UMR 5105, Université Grenoble Alpes, Grenoble, France
| | - Liad Mudrik
- Sagol School of Neuroscience, Tel-Aviv University, Tel-Aviv, Israel
- School of Psychological Sciences, Tel-Aviv University, Tel-Aviv, Israel
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Abstract
Durable impairments of consciousness are currently classified in three main neurological categories: comatose state, vegetative state (also recently coined unresponsive wakefulness syndrome) and minimally conscious state. While the introduction of minimally conscious state, in 2002, was a major progress to help clinicians recognize complex non-reflexive behaviours in the absence of functional communication, it raises several problems. The most important issue related to minimally conscious state lies in its criteria: while behavioural definition of minimally conscious state lacks any direct evidence of patient's conscious content or conscious state, it includes the adjective 'conscious'. I discuss this major problem in this review and propose a novel interpretation of minimally conscious state: its criteria do not inform us about the potential residual consciousness of patients, but they do inform us with certainty about the presence of a cortically mediated state. Based on this constructive criticism review, I suggest three proposals aiming at improving the way we describe the subjective and cognitive state of non-communicating patients. In particular, I present a tentative new classification of impairments of consciousness that combines behavioural evidence with functional brain imaging data, in order to probe directly and univocally residual conscious processes.
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Affiliation(s)
- Lionel Naccache
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, 75013, Paris, France
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurophysiology, 75013, Paris, France
- INSERM, U 1127, F-75013, Paris, France
- Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
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Hauger SL, Schanke AK, Andersson S, Chatelle C, Schnakers C, Løvstad M. The Clinical Diagnostic Utility of Electrophysiological Techniques in Assessment of Patients With Disorders of Consciousness Following Acquired Brain Injury: A Systematic Review. J Head Trauma Rehabil 2018; 32:185-196. [PMID: 27831962 DOI: 10.1097/htr.0000000000000267] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To investigate the diagnostic utility of electrophysiological recordings during active cognitive tasks in detecting residual cognitive capacities in patients with disorders of consciousness (DoC) after severe acquired brain injury. DESIGN Systematic review of empirical research in MEDLINE, Embase, PsycINFO, and Cochrane from January 2002 to March 2016. MAIN MEASURES Data extracted included sample size, type of electrophysiological technique and task design, rate of cognitive responders, false negatives and positives, and excluded subjects from the study analysis. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used for quality appraisal of the retrieved literature. RESULTS Twenty-four studies examining electrophysiological signs of command-following in patients with DoC were identified. Sensitivity rates in healthy controls demonstrated variable accuracy across the studies, ranging from 71% to 100%. In patients with DoC, specificity and sensitivity rates varied in the included studies, ranging from 0% to 100%. Pronounced heterogeneity was found between studies regarding methodological approaches, task design, and procedures of analysis, rendering comparison between studies challenging. CONCLUSION We are still far from establishing precise recommendations for standardized electrophysiological diagnostic procedures in DoC, but electrophysiological methods may add supplemental diagnostic information of covert cognition in some patients with DoC.
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Affiliation(s)
- S L Hauger
- Department of Research, Sunnaas Rehabilitation Hospital, Norway (Mrs Hauger and Drs Løvstad and Schanke); Department of Psychology, University of Oslo, Oslo, Norway (Drs Andersson, Løvstad, and Schanke); Laboratory for NeuroImaging of Coma and Consciousness, Massachusetts General Hospital, Boston, and Acute Neurorehabilitation Unit, Department of Clinical Neurosciences, University Hospital of Lausanne, Switzerland (Dr Chatelle); and Department of Neurosurgery, University of California, Los Angeles (Dr Schnakers)
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Juan E, Nguepnjo Nguissi NA, Tzovara A, Viceic D, Rusca M, Oddo M, Rossetti AO, De Lucia M. Evidence of trace conditioning in comatose patients revealed by the reactivation of EEG responses to alerting sounds. Neuroimage 2016; 141:530-41. [DOI: 10.1016/j.neuroimage.2016.07.039] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 06/08/2016] [Accepted: 07/17/2016] [Indexed: 11/20/2022] Open
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Blain-Moraes S, Boshra R, Ma HK, Mah R, Ruiter K, Avidan M, Connolly JF, Mashour GA. Normal Brain Response to Propofol in Advance of Recovery from Unresponsive Wakefulness Syndrome. Front Hum Neurosci 2016; 10:248. [PMID: 27313518 PMCID: PMC4889589 DOI: 10.3389/fnhum.2016.00248] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 05/13/2016] [Indexed: 11/23/2022] Open
Abstract
Up to 40% of individuals with unresponsive wakefulness syndrome (UWS) actually might be conscious. Recent attempts to detect covert consciousness in behaviorally unresponsive patients via neurophysiological patterns are limited by the need to compare data from brain-injured patients to healthy controls. In this report, we pilot an alternative within-subject approach by using propofol to perturb the brain state of a patient diagnosed with UWS. An auditory stimulation series was presented to the patient before, during, and after exposure to propofol while high-density electroencephalograph (EEG) was recorded. Baseline analysis revealed residual markers in the continuous EEG and event-related potentials (ERPs) that have been associated with conscious processing. However, these markers were significantly distorted by the patient’s pathology, challenging the interpretation of their functional significance. Upon exposure to propofol, changes in EEG characteristics were similar to what is seen in healthy individuals and ERPs associated with conscious processing disappeared. At the 1-month follow up, the patient had regained consciousness. We offer three alternative explanations for these results: (1) the patient was covertly consciousness, and was anesthetized by propofol administration; (2) the patient was unconscious, and the observed EEG changes were a propofol-specific phenomenon; and (3) the patient was unconscious, but his brain networks responded normally in a way that heralded the possibility of recovery. These alternatives will be tested in a larger study, and raise the intriguing possibility of using a general anesthetic as a probe of brain states in behaviorally unresponsive patients.
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Affiliation(s)
| | - Rober Boshra
- Department of Linguistics and Languages, McMaster University Hamilton, ON, Canada
| | - Heung Kan Ma
- Department of Anesthesia, McMaster University Hamilton, ON, Canada
| | - Richard Mah
- Department of Linguistics and Languages, McMaster University Hamilton, ON, Canada
| | - Kyle Ruiter
- Department of Linguistics and Languages, McMaster University Hamilton, ON, Canada
| | - Michael Avidan
- Department of Anesthesiology, Washington University St. Louis, MO, USA
| | - John F Connolly
- Department of Linguistics and Languages, McMaster University Hamilton, ON, Canada
| | - George A Mashour
- Department of Anesthesiology, University of Michigan Ann Arbor, MI, USA
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Tzovara A, Rossetti AO, Juan E, Suys T, Viceic D, Rusca M, Oddo M, Lucia MD. Prediction of awakening from hypothermic postanoxic coma based on auditory discrimination. Ann Neurol 2016; 79:748-757. [DOI: 10.1002/ana.24622] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 02/17/2016] [Accepted: 02/17/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Athina Tzovara
- Neuroimaging Research Laboratory, Department of Clinical Neurosciences; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
- Department of Psychiatry, Psychotherapy; and Psychosomatics and Neuroscience Centre Zurich; University of Zurich Switzerland
| | - Andrea O. Rossetti
- Neurology Service, Department of Clinical Neurosciences; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
| | - Elsa Juan
- Neuroimaging Research Laboratory, Department of Clinical Neurosciences; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
- Neurology Service, Department of Clinical Neurosciences; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
| | - Tamarah Suys
- Department of Intensive Care Medicine; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
| | | | - Marco Rusca
- Intensive Care Medicine Service; Valais Hospital; Sion Switzerland
| | - Mauro Oddo
- Department of Intensive Care Medicine; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
| | - Marzia De Lucia
- Neuroimaging Research Laboratory, Department of Clinical Neurosciences; Lausanne University Hospital and University of Lausanne; Lausanne Switzerland
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Gabriel D, Muzard E, Henriques J, Mignot C, Pazart L, André-Obadia N, Ortega JP, Moulin T. Replicability and impact of statistics in the detection of neural responses of consciousness: Table 1. Brain 2016; 139:e30. [DOI: 10.1093/brain/aww065] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Naccache L, Sitt J, King JR, Rohaut B, Faugeras F, Chennu S, Strauss M, Valente M, Engemann D, Raimondo F, Demertzi A, Bekinschtein T, Dehaene S. Reply: Replicability and impact of statistics in the detection of neural responses of consciousness. Brain 2016; 139:e31. [PMID: 27017190 DOI: 10.1093/brain/aww060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lionel Naccache
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurophysiology, Paris, France INSERM, U 1127, F-75013, Paris, France Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France Sorbonne Universités, UPMC Univ Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France
| | - Jacobo Sitt
- INSERM, U 1127, F-75013, Paris, France INSERM-CEA Cognitive Neuroimaging unit
- CEA/SAC/DSV/DRM/Neurospin Center, Gif/Yvette cedex, France
| | - Jean-Rémi King
- INSERM, U 1127, F-75013, Paris, France INSERM-CEA Cognitive Neuroimaging unit
- CEA/SAC/DSV/DRM/Neurospin Center, Gif/Yvette cedex, France
| | - Benjamin Rohaut
- AP-HP, Groupe hospitalier Pitié-Salpêtrière, Department of Neurology, Paris, France INSERM, U 1127, F-75013, Paris, France
| | | | - Srivas Chennu
- Department of Clinical Neurosciences, University of Cambridge, UK
| | - Mélanie Strauss
- INSERM-CEA Cognitive Neuroimaging unit
- CEA/SAC/DSV/DRM/Neurospin Center, Gif/Yvette cedex, France
| | - Mélanie Valente
- INSERM, U 1127, F-75013, Paris, France Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
| | - Denis Engemann
- INSERM, U 1127, F-75013, Paris, France Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
| | - Federico Raimondo
- INSERM, U 1127, F-75013, Paris, France Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
| | - Athena Demertzi
- Institut du Cerveau et de la Moelle épinière, ICM, PICNIC Lab, F-75013, Paris, France
| | | | - Stanislas Dehaene
- INSERM-CEA Cognitive Neuroimaging unit
- CEA/SAC/DSV/DRM/Neurospin Center, Gif/Yvette cedex, France Collège de France, 75005 Paris, France
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