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Marino M, Mantini D. Human brain imaging with high-density electroencephalography: Techniques and applications. J Physiol 2024. [PMID: 39173191 DOI: 10.1113/jp286639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2024] [Accepted: 07/30/2024] [Indexed: 08/24/2024] Open
Abstract
Electroencephalography (EEG) is a technique for non-invasively measuring neuronal activity in the human brain using electrodes placed on the participant's scalp. With the advancement of digital technologies, EEG analysis has evolved over time from the qualitative analysis of amplitude and frequency modulations to a comprehensive analysis of the complex spatiotemporal characteristics of the recorded signals. EEG is now considered a powerful tool for measuring neural processes in the same time frame in which they happen (i.e. the subsecond range). However, it is commonly argued that EEG suffers from low spatial resolution, which makes it difficult to localize the generators of EEG activity accurately and reliably. Today, the availability of high-density EEG (hdEEG) systems, combined with methods for incorporating information on head anatomy and sophisticated source-localization algorithms, has transformed EEG into an important neuroimaging tool. hdEEG offers researchers and clinicians a rich and varied range of applications. It can be used not only for investigating neural correlates in motor and cognitive neuroscience experiments, but also for clinical diagnosis, particularly in the detection of epilepsy and the characterization of neural impairments in a wide range of neurological disorders. Notably, the integration of hdEEG systems with other physiological recordings, such as kinematic and/or electromyography data, might be especially beneficial to better understand the neuromuscular mechanisms associated with deconditioning in ageing and neuromotor disorders, by mapping the neurokinematic and neuromuscular connectivity patterns directly in the brain.
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Affiliation(s)
- Marco Marino
- Movement Control and Neuroplasticity Research Group, KU Leuven, Belgium
- Department of General Psychology, University of Padua, Padua, Italy
| | - Dante Mantini
- Movement Control and Neuroplasticity Research Group, KU Leuven, Belgium
- Leuven Brain Institute, KU Leuven, Belgium
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Hack LM, Sikka P, Zhou K, Kawai M, Chow HS, Heifets B. Reduction in Trauma-Related Symptoms After Anesthetic-Induced Intra-Operative Dreaming. Am J Psychiatry 2024; 181:563-564. [PMID: 38476046 DOI: 10.1176/appi.ajp.20230698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Affiliation(s)
- Laura M Hack
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
| | - Pilleriin Sikka
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
| | - Kelly Zhou
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
| | - Makoto Kawai
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
| | - Harrison S Chow
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
| | - Boris Heifets
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, Calif. (Hack, Kawai, Heifets); Sierra Pacific Mental Illness Research, Education, and Clinical Center (MIRECC), VA Palo Alto Health Care System, Palo Alto, Calif. (Hack, Kawai); Department of Psychology, Stanford University, Stanford, Calif. (Sikka); Department of Psychology, University of Turku, Turku, Finland (Sikka); Department of Cognitive Neuroscience and Philosophy, University of Skövde, Skövde, Sweden (Sikka); Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, Calif. (Sikka, Zhou, Chow, Heifets)
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Tononi G, Boly M, Cirelli C. Consciousness and sleep. Neuron 2024; 112:1568-1594. [PMID: 38697113 PMCID: PMC11105109 DOI: 10.1016/j.neuron.2024.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/04/2024] [Accepted: 04/10/2024] [Indexed: 05/04/2024]
Abstract
Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.
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Affiliation(s)
- Giulio Tononi
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA.
| | - Melanie Boly
- Department of Neurology, University of Wisconsin, Madison, WI 53719, USA
| | - Chiara Cirelli
- Department of Psychiatry, University of Wisconsin, Madison, WI 53719, USA
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Schmierer T, Li T, Li Y. Harnessing machine learning for EEG signal analysis: Innovations in depth of anaesthesia assessment. Artif Intell Med 2024; 151:102869. [PMID: 38593683 DOI: 10.1016/j.artmed.2024.102869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 01/31/2024] [Accepted: 04/03/2024] [Indexed: 04/11/2024]
Abstract
Anaesthesia, crucial to surgical practice, is undergoing renewed scrutiny due to the integration of artificial intelligence in its medical use. The precise control over the temporary loss of consciousness is vital to ensure safe, pain-free procedures. Traditional methods of depth of anaesthesia (DoA) assessment, reliant on physical characteristics, have proven inconsistent due to individual variations. In response, electroencephalography (EEG) techniques have emerged, with indices such as the Bispectral Index offering quantifiable assessments. This literature review explores the current scope and frontier of DoA research, emphasising methods utilising EEG signals for effective clinical monitoring. This review offers a critical synthesis of recent advances, specifically focusing on electroencephalography (EEG) techniques and their role in enhancing clinical monitoring. By examining 117 high-impact papers, the review delves into the nuances of feature extraction, model building, and algorithm design in EEG-based DoA analysis. Comparative assessments of these studies highlight their methodological approaches and performance, including clinical correlations with established indices like the Bispectral Index. The review identifies knowledge gaps, particularly the need for improved collaboration for data access, which is essential for developing superior machine learning models and real-time predictive algorithms for patient management. It also calls for refined model evaluation processes to ensure robustness across diverse patient demographics and anaesthetic agents. The review underscores the potential of technological advancements to enhance precision, safety, and patient outcomes in anaesthesia, paving the way for a new standard in anaesthetic care. The findings of this review contribute to the ongoing discourse on the application of EEG in anaesthesia, providing insights into the potential for technological advancement in this critical area of medical practice.
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Affiliation(s)
- Thomas Schmierer
- School of Mathematics, Physics and Computing, University of Southern Queensland, Australia.
| | - Tianning Li
- School of Mathematics, Physics and Computing, University of Southern Queensland, Australia.
| | - Yan Li
- School of Mathematics, Physics and Computing, University of Southern Queensland, Australia.
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Vrijdag XCE, Hallum LE, Tonks EI, van Waart H, Mitchell SJ, Sleigh JW. Support-vector classification of low-dose nitrous oxide administration with multi-channel EEG power spectra. J Clin Monit Comput 2024; 38:363-371. [PMID: 37440117 PMCID: PMC10995006 DOI: 10.1007/s10877-023-01054-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/25/2023] [Indexed: 07/14/2023]
Abstract
Support-vector machines (SVMs) can potentially improve patient monitoring during nitrous oxide anaesthesia. By elucidating the effects of low-dose nitrous oxide on the power spectra of multi-channel EEG recordings, we quantified the degree to which these effects generalise across participants. In this single-blind, cross-over study, 32-channel EEG was recorded from 12 healthy participants exposed to 0, 20, 30 and 40% end-tidal nitrous oxide. Features of the delta-, theta-, alpha- and beta-band power were used within a 12-fold, participant-wise cross-validation framework to train and test two SVMs: (1) binary SVM classifying EEG during 0 or 40% exposure (chance = 50%); (2) multi-class SVM classifying EEG during 0, 20, 30 or 40% exposure (chance = 25%). Both the binary (accuracy 92%) and the multi-class (accuracy 52%) SVMs classified EEG recordings at rates significantly better than chance (p < 0.001 and p = 0.01, respectively). To determine the relative importance of frequency band features for classification accuracy, we systematically removed features before re-training and re-testing the SVMs. This showed the relative importance of decreased delta power and the frontal region. SVM classification identified that the most important effects of nitrous oxide were found in the delta band in the frontal electrodes that was consistent between participants. Furthermore, support-vector classification of nitrous oxide dosage is a promising method that might be used to improve patient monitoring during nitrous oxide anaesthesia.
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Affiliation(s)
- Xavier C E Vrijdag
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
| | - Luke E Hallum
- Department of Mechanical and Mechatronics Engineering, University of Auckland, Auckland, 1142, New Zealand
| | - Emma I Tonks
- Department of Mechanical and Mechatronics Engineering, University of Auckland, Auckland, 1142, New Zealand
| | - Hanna van Waart
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Simon J Mitchell
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
- Department of Anaesthesia, Auckland City Hospital, Auckland, 1023, New Zealand
| | - Jamie W Sleigh
- Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
- Department of Anaesthesia, Waikato Hospital, Hamilton, 3240, New Zealand
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Cecconi B, Montupil J, Mortaheb S, Panda R, Sanders RD, Phillips C, Alnagger N, Remacle E, Defresne A, Boly M, Bahri MA, Lamalle L, Laureys S, Gosseries O, Bonhomme V, Annen J. Study protocol: Cerebral characterization of sensory gating in disconnected dreaming states during propofol anesthesia using fMRI. Front Neurosci 2024; 18:1306344. [PMID: 38419667 PMCID: PMC10900985 DOI: 10.3389/fnins.2024.1306344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
Background Disconnected consciousness describes a state in which subjective experience (i.e., consciousness) becomes isolated from the external world. It appears frequently during sleep or sedation, when subjective experiences remain vivid but are unaffected by external stimuli. Traditional methods of differentiating connected and disconnected consciousness, such as relying on behavioral responsiveness or on post-anesthesia reports, have demonstrated limited accuracy: unresponsiveness has been shown to not necessarily equate to unconsciousness and amnesic effects of anesthesia and sleep can impair explicit recollection of events occurred during sleep/sedation. Due to these methodological challenges, our understanding of the neural mechanisms underlying sensory disconnection remains limited. Methods To overcome these methodological challenges, we employ a distinctive strategy by combining a serial awakening paradigm with auditory stimulation during mild propofol sedation. While under sedation, participants are systematically exposed to auditory stimuli and questioned about their subjective experience (to assess consciousness) and their awareness of the sounds (to evaluate connectedness/disconnectedness from the environment). The data collected through interviews are used to categorize participants into connected and disconnected consciousness states. This method circumvents the requirement for responsiveness in assessing consciousness and mitigates amnesic effects of anesthesia as participants are questioned while still under sedation. Functional MRI data are concurrently collected to investigate cerebral activity patterns during connected and disconnected states, to elucidate sensory disconnection neural gating mechanisms. We examine whether this gating mechanism resides at the thalamic level or results from disruptions in information propagation to higher cortices. Furthermore, we explore the potential role of slow-wave activity (SWA) in inducing disconnected consciousness by quantifying high-frequency BOLD oscillations, a known correlate of slow-wave activity. Discussion This study represents a notable advancement in the investigation of sensory disconnection. The serial awakening paradigm effectively mitigates amnesic effects by collecting reports immediately after regaining responsiveness, while still under sedation. Ultimately, this research holds the potential to understand how sensory gating is achieved at the neural level. These biomarkers might be relevant for the development of sensitive anesthesia monitoring to avoid intraoperative connected consciousness and for the assessment of patients suffering from pathologically reduced consciousness. Clinical trial registration European Union Drug Regulating Authorities Clinical Trials Database (EudraCT), identifier 2020-003524-17.
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Affiliation(s)
- Benedetta Cecconi
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Javier Montupil
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Centre Hospitalier Régional de la Citadelle (CHR Citadelle), Liège, Belgium
| | - Sepehr Mortaheb
- Physiology of Cognition Research Lab, GIGA-Consciousness, GIGA Institute, University of Liège, Liege, Belgium
| | - Rajanikant Panda
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Robert D. Sanders
- Central Clinical School, Sydney Medical School & NHMRC Clinical Trials Centre, University of Sydney, Camperdown, NSW, Australia
- Department of Anaesthetics & Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
| | - Christophe Phillips
- GIGA-CRC—In vivo Imaging—Neuroimaging, Data Acquisition and Processing, GIGA Institute, University of Liège, Liège, Belgium
| | - Naji Alnagger
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Emma Remacle
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
| | - Aline Defresne
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Centre Hospitalier Régional de la Citadelle (CHR Citadelle), Liège, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liège University Hospital, Liège, Belgium
| | - Melanie Boly
- Department of Psychiatry, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin, Madison, WI, United States
| | - Mohamed Ali Bahri
- GIGA-CRC—In vivo Imaging—Aging & Memory, GIGA Institute, University of Liège, Liège, Belgium
| | - Laurent Lamalle
- GIGA-CRC—In vivo Imaging—Aging & Memory, GIGA Institute, University of Liège, Liège, Belgium
| | - Steven Laureys
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
- Cervo Brain Research Centre, University Institute in Mental Health of Quebec, Québec, QC, Canada
- Consciousness Science Institute, Hangzhou Normal University, Hangzhou, China
| | - Olivia Gosseries
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
| | - Vincent Bonhomme
- Anesthesia and Perioperative Neuroscience Laboratory, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liège University Hospital, Liège, Belgium
| | - Jitka Annen
- Coma Science Group, GIGA-Consciousness, GIGA Institute, University of Liège, Liège, Belgium
- Centre du Cerveau, University Hospital of Liège, Liège, Belgium
- Department of Data Analysis, University of Ghent, Ghent, Belgium
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Casey CP, Tanabe S, Farahbakhsh ZZ, Parker M, Bo A, White M, Ballweg T, Mcintosh A, Filbey W, Banks MI, Saalmann YB, Pearce RA, Sanders RD. Evaluation of putative signatures of consciousness using specific definitions of responsiveness, connectedness, and consciousness. Br J Anaesth 2024; 132:300-311. [PMID: 37914581 PMCID: PMC10808836 DOI: 10.1016/j.bja.2023.09.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 09/15/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
BACKGROUND Understanding the neural correlates of consciousness has important ramifications for the theoretical understanding of consciousness and for clinical anaesthesia. A major limitation of prior studies is the use of responsiveness as an index of consciousness. We identified a collection of measures derived from unresponsive subjects and more specifically their association with consciousness (any subjective experience) or connectedness (specific experience of environmental stimuli). METHODS Using published data generated through the UNderstanding Consciousness Connectedness and Intra-Operative Unresponsiveness Study (NCT03284307), we evaluated 10 previously published resting-state EEG-based measures that were derived using unresponsiveness as a proxy for unconsciousness. Measures were tested across dexmedetomidine and propofol sedation and natural sleep. These markers represent the complexity, connectivity, cross-frequency coupling, graph theory, and power spectrum measures. RESULTS Although many of the proposed markers were associated with consciousness per se (reported subjective experience), none were specific to consciousness alone; rather, each was also associated with connectedness (i.e. awareness of the environment). In addition, multiple markers showed no association with consciousness and were associated only with connectedness. Of the markers tested, loss of normalised-symbolic transfer entropy (front to back) was associated with connectedness across all three experimental conditions, whereas the transition from disconnected consciousness to unconsciousness was associated with significant decreases in permutation entropy and spectral exponent (P<0.05 for all conditions). CONCLUSIONS None of the proposed EEG-based neural correlates of unresponsiveness corresponded solely to consciousness, highlighting the need for a more conservative use of the term (un)consciousness when assessing unresponsive participants. CLINICAL TRIAL REGISTRATION NCT03284307.
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Affiliation(s)
- Cameron P Casey
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Sean Tanabe
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Zahra Z Farahbakhsh
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Margaret Parker
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Amber Bo
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Marissa White
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Tyler Ballweg
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Andrew Mcintosh
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - William Filbey
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Matthew I Banks
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Yuri B Saalmann
- Department of Psychology, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Robert D Sanders
- Specialty of Anaesthetics & NHMRC Clinical Trials Centre, University of Sydney, Camperdown, NSW, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Camperdown, NSW, Australia; Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, NSW, Australia.
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Jiang Y, Sleigh J. Consciousness and General Anesthesia: Challenges for Measuring the Depth of Anesthesia. Anesthesiology 2024; 140:313-328. [PMID: 38193734 DOI: 10.1097/aln.0000000000004830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2024]
Abstract
The optimal consciousness level required for general anesthesia with surgery is unclear, but in existing practice, anesthetic oblivion, may be incomplete. This article discusses the concept of consciousness, how it is altered by anesthetics, the challenges for assessing consciousness, currently used technologies for assessing anesthesia levels, and future research directions. Wakefulness is marked by a subjective experience of existence (consciousness), perception of input from the body or the environment (connectedness), the ability for volitional responsiveness, and a sense of continuity in time. Anesthetic drugs may selectively impair some of these components without complete extinction of the subjective experience of existence. In agreement with Sanders et al. (2012), the authors propose that a state of disconnected consciousness is the optimal level of anesthesia, as it likely avoids both awareness and the possible dangers of oversedation. However, at present, there are no reliably tested indices that can discriminate between connected consciousness, disconnected consciousness, and complete unconsciousness.
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Affiliation(s)
- Yandong Jiang
- Department of Anesthesiology, Critical Care and Pain Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas
| | - Jamie Sleigh
- Department of Anesthesiology, University of Auckland, Hamilton, New Zealand
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Montupil J, Cardone P, Staquet C, Bonhomme A, Defresne A, Martial C, Alnagger NL, Gosseries O, Bonhomme V. The nature of consciousness in anaesthesia. BJA OPEN 2023; 8:100224. [PMID: 37780201 PMCID: PMC10539891 DOI: 10.1016/j.bjao.2023.100224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 08/28/2023] [Indexed: 10/03/2023]
Abstract
Neuroscientists agree on the value of locating the source of consciousness within the brain. Anaesthesiologists are no exception, and have their own operational definition of consciousness based on phenomenological observations during anaesthesia. The full functional correlates of consciousness are yet to be precisely identified, however rapidly evolving progress in this scientific domain has yielded several theories that attempt to model the generation of consciousness. They have received variable support from experimental observations, including those involving anaesthesia and its ability to reversibly modulate different aspects of consciousness. Aside from the interest in a better understanding of the mechanisms of consciousness, exploring the functional tenets of the phenomenological consciousness states of general anaesthesia has the potential to ultimately improve patient management. It could facilitate the design of specific monitoring devices and approaches, aiming at reliably detecting each of the possible states of consciousness during an anaesthetic procedure, including total absence of mental content (unconsciousness), and internal awareness (sensation of self and internal thoughts) with or without conscious perception of the environment (connected or disconnected consciousness, respectively). Indeed, it must be noted that unresponsiveness is not sufficient to infer absence of connectedness or even absence of consciousness. This narrative review presents the current knowledge in this field from a system-level, underlining the contribution of anaesthesia studies in supporting theories of consciousness, and proposing directions for future research.
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Affiliation(s)
- Javier Montupil
- Anesthesia and Perioperative Neuroscience Laboratory, Liege, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liege, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Citadelle Regional Hospital, Liege, Belgium
| | - Paolo Cardone
- Coma Science Group, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium
- Centre du Cerveau, Liege University Hospital, Liege, Belgium
| | - Cécile Staquet
- Anesthesia and Perioperative Neuroscience Laboratory, Liege, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liege, Belgium
| | - Arthur Bonhomme
- Coma Science Group, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium
| | - Aline Defresne
- Anesthesia and Perioperative Neuroscience Laboratory, Liege, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liege, Belgium
- University Department of Anesthesia and Intensive Care Medicine, Citadelle Regional Hospital, Liege, Belgium
| | - Charlotte Martial
- Coma Science Group, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium
- Centre du Cerveau, Liege University Hospital, Liege, Belgium
| | - Naji L.N. Alnagger
- Coma Science Group, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium
- Centre du Cerveau, Liege University Hospital, Liege, Belgium
| | - Olivia Gosseries
- Coma Science Group, GIGA-Consciousness Thematic Unit, GIGA-Research, Liege University, Liege, Belgium
- Centre du Cerveau, Liege University Hospital, Liege, Belgium
| | - Vincent Bonhomme
- Anesthesia and Perioperative Neuroscience Laboratory, Liege, Belgium
- Department of Anesthesia and Intensive Care Medicine, Liege, Belgium
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Munro BA, Merenick DR, Gee JM, Pang DSJ. Use of Loss of Righting Reflex to Assess Susceptibility to Carbon Dioxide Gas in Three Mouse Strains. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2023; 62:553-558. [PMID: 37770194 PMCID: PMC10772915 DOI: 10.30802/aalas-jaalas-23-000035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/20/2023] [Accepted: 07/24/2023] [Indexed: 09/30/2023]
Abstract
Exposure to CO₂ gas is a common rodent euthanasia method. CO₂ activates nociceptors in rats and is painful to humans at concentrations equal to or greater than 32.5% The concentration of CO₂ at which rodents become unconsciousness is inadequately defined. We used loss of righting reflex (LORR) to identify the concentration at which CO₂ caused loss of consciousness in C57Bl/6, CD1 and 129P3J mice (16 females and 16 males per strain). We used a custom built, rotating, motorized cylinder to determine LORR as CO₂ concentrations were increased. Two LORR assessment methods were used: 1) a 1-Paw assessment in which the righting reflex was considered to be present if one or more paws contacted the cylinder after rotation into dorsal recumbency and 2) a 4-Paw assessment in which the righting reflex was considered to be present only if all 4 paws contacted the cylinder. LORR test data were analyzed with Probit regression and dose response curves were plotted. 1-Paw EC95 values (CO₂ concentration at which LORR occurred for 95% of the population) were: C57Bl/6; 30.7%, CD1; 26.2%, 129P3J; 20.1%. The EC95 for C57Bl/6 was significantly higher than that of the 129P3J mice, with no significant differences between other strains. Four-Paw EC95 values were: C57Bl/6; 22.8%, CD1; 25.3%, 129P3J; 20.1%. Values for 129P3J mice were significantly lower than those of CD1 mice), with no significant difference between other strains. The EC95 varied significantly between 1-Paw and 4-Paw methods only for C57Bl/6 mice. These results suggest a potential for nociception and pain to occur in some individuals of some mouse strains during CO₂ euthanasia.
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Affiliation(s)
- Brittany A Munro
- Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada
| | - Dexter R Merenick
- Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada
| | - Julia M Gee
- College of Engineering and Physical Sciences, University of Guelph, Ontario, Canada
| | - Daniel SJ Pang
- Faculty of Veterinary Medicine, University of Calgary, Alberta, Canada
- Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
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11
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Munn BR, Müller EJ, Medel V, Naismith SL, Lizier JT, Sanders RD, Shine JM. Neuronal connected burst cascades bridge macroscale adaptive signatures across arousal states. Nat Commun 2023; 14:6846. [PMID: 37891167 PMCID: PMC10611774 DOI: 10.1038/s41467-023-42465-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 10/11/2023] [Indexed: 10/29/2023] Open
Abstract
The human brain displays a rich repertoire of states that emerge from the microscopic interactions of cortical and subcortical neurons. Difficulties inherent within large-scale simultaneous neuronal recording limit our ability to link biophysical processes at the microscale to emergent macroscopic brain states. Here we introduce a microscale biophysical network model of layer-5 pyramidal neurons that display graded coarse-sampled dynamics matching those observed in macroscale electrophysiological recordings from macaques and humans. We invert our model to identify the neuronal spike and burst dynamics that differentiate unconscious, dreaming, and awake arousal states and provide insights into their functional signatures. We further show that neuromodulatory arousal can mediate different modes of neuronal dynamics around a low-dimensional energy landscape, which in turn changes the response of the model to external stimuli. Our results highlight the promise of multiscale modelling to bridge theories of consciousness across spatiotemporal scales.
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Affiliation(s)
- Brandon R Munn
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia.
- Complex Systems, School of Physics, University of Sydney, Sydney, NSW, Australia.
- Centre for Complex Systems, The University of Sydney, Sydney, NSW, Australia.
| | - Eli J Müller
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Complex Systems, School of Physics, University of Sydney, Sydney, NSW, Australia
- Centre for Complex Systems, The University of Sydney, Sydney, NSW, Australia
| | - Vicente Medel
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Latin American Brain Health Institute (BrainLat), Universidad Adolfo Ibañez, Santiago, Chile
| | - Sharon L Naismith
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- School of Psychology, Faculty of Science & Charles Perkins Centre, The University of Sydney, Sydney, NSW, Australia
| | - Joseph T Lizier
- Centre for Complex Systems, The University of Sydney, Sydney, NSW, Australia
- School of Computer Science, The University of Sydney, Sydney, NSW, Australia
| | - Robert D Sanders
- Department of Anaesthetics & Institute of Academic Surgery, Royal Prince Alfred Hospital, Camperdown, Australia
- Central Clinical School & NHMRC Clinical Trials Centre, The University of Sydney, Sydney, NSW, Australia
| | - James M Shine
- Brain and Mind Centre, The University of Sydney, Sydney, NSW, Australia
- Complex Systems, School of Physics, University of Sydney, Sydney, NSW, Australia
- Centre for Complex Systems, The University of Sydney, Sydney, NSW, Australia
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12
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Turner AJF, Wehrman J, Sanders RD. Similarities in consciousness occurring during sleep and sedation. Br J Anaesth 2023; 131:632-633. [PMID: 37718091 DOI: 10.1016/j.bja.2023.07.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/25/2023] [Accepted: 07/20/2023] [Indexed: 09/19/2023] Open
Abstract
The subjective experiences of sedation or anaesthesia are underexplored. A recent study by Valli and colleagues (Br J Anaesth 2023; 131: 348-59) found similar frequency and content of recalled experiences after both non-rapid eye movement sleep and target-controlled infusions of propofol or dexmedetomidine titrated to verbal unresponsiveness. The authors find that the phenomenological similarities between consciousness during sleep and sedation mirror their physiological similarities. Intriguingly, in this small sample, conscious experience did not show a dose-dependent response suggesting other factors are important in determining the propensity for consciousness under sedation.
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Affiliation(s)
- Andrew J F Turner
- Department of Anaesthesia, Royal North Shore Hospital, Sydney, NSW, Australia
| | - Jordan Wehrman
- Central Clinical School Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Robert D Sanders
- Central Clinical School Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; NHMRC Clinical Trials Centre, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Department of Anaesthetics and Institute of Academic Surgery, Royal Prince Alfred Hospital, Sydney Local Health District, Camperdown, NSW, Australia.
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13
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McCulloch TJ, Sanders RD. Depth of anaesthesia monitoring: time to reject the index? Br J Anaesth 2023; 131:196-199. [PMID: 37198033 DOI: 10.1016/j.bja.2023.04.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 05/19/2023] Open
Abstract
Depth of anaesthesia monitors can fail to detect consciousness under anaesthesia, primarily because they rely on the frontal EEG, which does not arise from a neural correlate of consciousness. A study published in a previous issue of the British Journal of Anaesthesia showed that indices produced by the different commercial monitors can give highly discordant results when analysing changes in the frontal EEG. Anaesthetists could benefit from routinely assessing the raw EEG and its spectrogram, rather than relying solely on an index produced by a depth of anaesthesia monitor.
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Affiliation(s)
- Timothy J McCulloch
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney Local Health District, Sydney, NSW, Australia.
| | - Robert D Sanders
- Central Clinical School, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia; Department of Anaesthetics, Royal Prince Alfred Hospital, Sydney Local Health District, Sydney, NSW, Australia; Institute of Academic Surgery, Royal Prince Alfred Hospital, Sydney Local Health District, Sydney, NSW, Australia; NHMRC Clinical Trials Centre, University of Sydney, Sydney, NSW, Australia
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14
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Valli K, Radek L, Kallionpää RE, Scheinin A, Långsjö J, Kaisti K, Kantonen O, Korhonen J, Vahlberg T, Revonsuo A, Scheinin H. Subjective experiences during dexmedetomidine- or propofol-induced unresponsiveness and non-rapid eye movement sleep in healthy male subjects. Br J Anaesth 2023; 131:348-359. [PMID: 37268445 PMCID: PMC10375502 DOI: 10.1016/j.bja.2023.04.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 06/04/2023] Open
Abstract
BACKGROUND Anaesthetic-induced unresponsiveness and non-rapid eye movement (NREM) sleep share common neural pathways and neurophysiological features. We hypothesised that these states bear resemblance also at the experiential level. METHODS We compared, in a within-subject design, the prevalence and content of experiences in reports obtained after anaesthetic-induced unresponsiveness and NREM sleep. Healthy males (N=39) received dexmedetomidine (n=20) or propofol (n=19) in stepwise doses to induce unresponsiveness. Those rousable were interviewed and left unstimulated, and the procedure was repeated. Finally, the anaesthetic dose was increased 50%, and the participants were interviewed after recovery. The same participants (N=37) were also later interviewed after NREM sleep awakenings. RESULTS Most subjects were rousable, with no difference between anaesthetic agents (P=0.480). Lower drug plasma concentrations were associated with being rousable for both dexmedetomidine (P=0.007) and propofol (P=0.002) but not with recall of experiences in either drug group (dexmedetomidine: P=0.543; propofol: P=0.460). Of the 76 and 73 interviews performed after anaesthetic-induced unresponsiveness and NREM sleep, 69.7% and 64.4% included experiences, respectively. Recall did not differ between anaesthetic-induced unresponsiveness and NREM sleep (P=0.581), or between dexmedetomidine and propofol in any of the three awakening rounds (P>0.05). Disconnected dream-like experiences (62.3% vs 51.1%; P=0.418) and memory incorporation of the research setting (88.7% vs 78.7%; P=0.204) were equally often present in anaesthesia and sleep interviews, respectively, whereas awareness, signifying connected consciousness, was rarely reported in either state. CONCLUSIONS Anaesthetic-induced unresponsiveness and NREM sleep are characterised by disconnected conscious experiences with corresponding recall frequencies and content. CLINICAL TRIAL REGISTRATION Clinical trial registration. This study was part of a larger study registered at ClinicalTrials.gov (NCT01889004).
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Affiliation(s)
- Katja Valli
- Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Skövde, Sweden.
| | - Linda Radek
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Roosa E Kallionpää
- Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland
| | - Annalotta Scheinin
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Jaakko Långsjö
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Intensive Care, Tampere University Hospital, Tampere, Finland
| | - Kaike Kaisti
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Department of Anesthesiology and Intensive Care, Oulu University Hospital, Oulu, Finland
| | - Oskari Kantonen
- Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland
| | - Jarno Korhonen
- Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland
| | - Tero Vahlberg
- Institute of Clinical Medicine, Biostatistics, University of Turku and Turku University Hospital, Turku, Finland
| | - Antti Revonsuo
- Department of Psychology and Speech-Language Pathology, Turku Brain and Mind Center, University of Turku, Turku, Finland; Department of Cognitive Neuroscience and Philosophy, School of Bioscience, University of Skövde, Skövde, Sweden
| | - Harry Scheinin
- Department of Perioperative Services, Intensive Care and Pain Medicine, Turku University Hospital, Turku, Finland; Turku PET Centre, University of Turku and Turku University Hospital, Turku, Finland; Institute of Biomedicine and Unit of Clinical Pharmacology, University of Turku and Turku University Hospital, Turku, Finland
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15
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Guay CS, Hight D, Gupta G, Kafashan M, Luong AH, Avidan MS, Brown EN, Palanca BJA. Breathe-squeeze: pharmacodynamics of a stimulus-free behavioural paradigm to track conscious states during sedation ☆. Br J Anaesth 2023; 130:557-566. [PMID: 36967282 PMCID: PMC11140841 DOI: 10.1016/j.bja.2023.01.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 01/03/2023] [Accepted: 01/16/2023] [Indexed: 04/01/2023] Open
Abstract
BACKGROUND Conscious states are typically inferred through responses to auditory tasks and noxious stimulation. We report the use of a stimulus-free behavioural paradigm to track state transitions in responsiveness during dexmedetomidine sedation. We hypothesised that estimated dexmedetomidine effect-site (Ce) concentrations would be higher at loss of responsiveness (LOR) compared with return of responsiveness (ROR), and both would be lower than comparable studies that used stimulus-based assessments. METHODS Closed-Loop Acoustic Stimulation during Sedation with Dexmedetomidine data were analysed for secondary analysis. Fourteen healthy volunteers were asked to perform the breathe-squeeze task of gripping a dynamometer when inspiring and releasing it when expiring. LOR was defined as five inspirations without accompanied squeezes; ROR was defined as the return of five inspirations accompanied by squeezes. Brain states were monitored using 64-channel EEG. Dexmedetomidine was administered as a target-controlled infusion, with Ce estimated from a pharmacokinetic model. RESULTS Counter to our hypothesis, mean estimated dexmedetomidine Ce was lower at LOR (0.92 ng ml-1; 95% confidence interval: 0.69-1.15) than at ROR (1.43 ng ml-1; 95% confidence interval: 1.27-1.58) (paired t-test; P=0.002). LOR was characterised by progressively increasing fronto-occipital EEG power in the 0.5-8 Hz band and loss of occipital alpha (8-12 Hz) and global beta (16-30 Hz) power. These EEG changes reverted at ROR. CONCLUSIONS The breathe-squeeze task can effectively track changes in responsiveness during sedation without external stimuli and might be more sensitive to state changes than stimulus-based tasks. It should be considered when perturbation of brain states is undesirable. CLINICAL TRIAL REGISTRATION NCT04206059.
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Affiliation(s)
- Christian S Guay
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA.
| | - Darren Hight
- Department of Anaesthesiology & Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Gaurang Gupta
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - MohammadMehdi Kafashan
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Anhthi H Luong
- Columbia University Mailman School of Public Health, New York, NY, USA
| | - Michael S Avidan
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ben Julian A Palanca
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Psychiatry, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, MO, USA; Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA; Center on Biological Rhythms and Sleep, Washington University in St. Louis, St. Louis, MO, USA
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16
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Aamodt A, Sevenius Nilsen A, Markhus R, Kusztor A, HasanzadehMoghadam F, Kauppi N, Thürer B, Storm JF, Juel BE. EEG Lempel-Ziv complexity varies with sleep stage, but does not seem to track dream experience. Front Hum Neurosci 2023; 16:987714. [PMID: 36704096 PMCID: PMC9871639 DOI: 10.3389/fnhum.2022.987714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 12/14/2022] [Indexed: 01/12/2023] Open
Abstract
In a recent electroencephalography (EEG) sleep study inspired by complexity theories of consciousness, we found that multi-channel signal diversity progressively decreased from wakefulness to slow wave sleep, but failed to find any significant difference between dreaming and non-dreaming awakenings within the same sleep stage (NREM2). However, we did find that multi-channel Lempel-Ziv complexity (LZC) measured over the posterior cortex increased with more perceptual ratings of NREM2 dream experience along a thought-perceptual axis. In this follow-up study, we re-tested our previous findings, using a slightly different approach. Partial sleep-deprivation was followed by evening sleep experiments, with repeated awakenings and immediate dream reports. Participants reported whether they had been dreaming, and were asked to rate how diverse, vivid, perceptual, and thought-like the contents of their dreams were. High density (64 channel) EEG was recorded throughout the experiment, and mean single-channel LZC was calculated for each 30 s sleep epoch. LZC progressively decreased with depth of non-REM sleep. Surprisingly, estimated marginal mean LZC was slightly higher for NREM1 than for wakefulness, but the difference did not remain significant after adjusting for multiple comparisons. We found no significant difference in LZC between dream and non-dream awakenings, nor any significant relationship between LZC and subjective ratings of dream experience, within the same sleep stage (NREM2). The failure to reproduce our own previous finding of a positive correlation between posterior LZC and more perceptual dream experiences, or to find any other correlation between brain signal complexity and subjective experience within NREM2 sleep, raises the question of whether EEG LZC is really a reliable correlate of richness of experience as such, within the same sleep stage.
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Affiliation(s)
- Arnfinn Aamodt
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway,*Correspondence: Arnfinn Aamodt,
| | - André Sevenius Nilsen
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rune Markhus
- National Centre for Epilepsy, Oslo University Hospital, Oslo, Norway
| | - Anikó Kusztor
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway,School of Psychological Sciences, Monash University, Clayton, VIC, Australia
| | - Fatemeh HasanzadehMoghadam
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Nils Kauppi
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Benjamin Thürer
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Johan Frederik Storm
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Bjørn Erik Juel
- Brain Signalling Lab, Division of Physiology, Faculty of Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway,Bjørn Erik Juel,
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17
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Wehrman JJ, Chung CC, Sanders R. Anaesthetics and time perception: A review. Q J Exp Psychol (Hove) 2023:17470218221144614. [PMID: 36453756 DOI: 10.1177/17470218221144614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Consciousness requires subjective experience in the "now." Establishing "now," however, necessitates temporal processing. In the current article, we review one method of altering consciousness, anaesthetic drug administration, and its effects on perceived duration. We searched PubMed, PsycInfo, and ScienceDirect databases, and article reference sections, for combinations of anaesthetic drugs and time perception tasks, finding a total of 36 articles which met our inclusion criteria. We categorised these articles with regard to whether they altered the felt passage of time, short or long interval timing, or were motor timing tasks. We found that various drugs alter the perceived passage of time; ketamine makes time subjectively slow down while GABAergic drugs make time subjectively speed up. At a short interval there is little established evidence of a shift in time perception, though temporal estimates appear more variable. Similarly, when asked to use time to optimise responses (i.e., in motor timing tasks), various anaesthetic agents make timing more variable. Longer durations are estimated as lasting longer than their objective duration, though there is some variation across articles in this regard. We conclude by proposing further experiments to examine time perception under altered states of consciousness and ask whether it is possible to perceive the passage of time of events which do not necessarily reach the level of conscious perception. The variety of methods used raises the need for more systematic investigations of time perception under anaesthesia. We encourage future investigations into the overlap of consciousness and time perception to advance both fields.
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Affiliation(s)
| | - Clara C Chung
- Royal Prince Alfred Hospital, Sydney, NSW, Australia
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18
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Sevenius Nilsen A, Juel BE, Thürer B, Aamodt A, Storm JF. Are we really unconscious in “unconscious” states? Common assumptions revisited. Front Hum Neurosci 2022; 16:987051. [PMID: 36277049 PMCID: PMC9581328 DOI: 10.3389/fnhum.2022.987051] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 09/08/2022] [Indexed: 12/05/2022] Open
Abstract
In the field of consciousness science, there is a tradition to categorize certain states such as slow-wave non-REM sleep and deep general anesthesia as “unconscious”. While this categorization seems reasonable at first glance, careful investigations have revealed that it is not so simple. Given that (1) behavioral signs of (un-)consciousness can be unreliable, (2) subjective reports of (un-)consciousness can be unreliable, and, (3) states presumed to be unconscious are not always devoid of reported experience, there are reasons to reexamine our traditional assumptions about “states of unconsciousness”. While these issues are not novel, and may be partly semantic, they have implications both for scientific progress and clinical practice. We suggest that focusing on approaches that provide a more pragmatic and nuanced characterization of different experimental conditions may promote clarity in the field going forward, and help us build stronger foundations for future studies.
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Affiliation(s)
- Andre Sevenius Nilsen
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
- *Correspondence: Andre Sevenius Nilsen,
| | - Bjørn E. Juel
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
- School of Medicine and Public Health, Wisconsin Institute for Sleep and Consciousness, University of Wisconsin-Madison, Madison, WI, United States
- Bjørn E. Juel,
| | - Benjamin Thürer
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
| | - Arnfinn Aamodt
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
| | - Johan F. Storm
- Department of Physiology, Institute of Basic Medicine, University of Oslo, Oslo, Norway
- Johan F. Storm,
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19
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Mashour GA, Pal D, Brown EN. Prefrontal cortex as a key node in arousal circuitry. Trends Neurosci 2022; 45:722-732. [PMID: 35995629 PMCID: PMC9492635 DOI: 10.1016/j.tins.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/02/2022] [Accepted: 07/31/2022] [Indexed: 10/15/2022]
Abstract
The role of the prefrontal cortex (PFC) in the mechanism of consciousness is a matter of active debate. Most theoretical and empirical investigations have focused on whether the PFC is critical for the content of consciousness (i.e., the qualitative aspects of conscious experience). However, there is emerging evidence that, in addition to its well-established roles in cognition, the PFC is a key regulator of the level of consciousness (i.e., the global state of arousal). In this opinion article we review recent data supporting the hypothesis that the medial PFC is a critical node in arousal-promoting networks.
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Affiliation(s)
- George A Mashour
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA; Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA; Center for Consciousness Science, University of Michigan, Ann Arbor, MI, USA; Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA.
| | - Dinesh Pal
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, USA; Center for Consciousness Science, University of Michigan, Ann Arbor, MI, USA; Michigan Neuroscience Institute, University of Michigan, Ann Arbor, MI, USA; Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA; Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Emery N Brown
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA; Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA; Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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20
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Hight D, Sleigh J. Consciousness and the outside world: is there anyone listening? Br J Anaesth 2022; 128:895-897. [DOI: 10.1016/j.bja.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 01/27/2022] [Accepted: 02/05/2022] [Indexed: 11/29/2022] Open
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