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Joksimovic SM, Sampath D, Krishnan K, Covey DF, Jevtovic-Todorovic V, Raol YH, Todorovic SM. Differential effects of the novel neurosteroid hypnotic (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile on electroencephalogram activity in male and female rats. Br J Anaesth 2021; 127:435-446. [PMID: 33972091 PMCID: PMC8451239 DOI: 10.1016/j.bja.2021.03.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND We recently showed that a neurosteroid analogue, (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH), induced hypnosis in rats. The aim of the present study was to evaluate the hypnotic and anaesthetic potential of 3β-OH further using electroencephalography. METHODS We used behavioural assessment and cortical electroencephalogram (EEG) spectral power analysis to examine hypnotic and anaesthetic effects of 3β-OH (30 and 60 mg kg-1) administered intraperitoneally or intravenously to young adult male and female rats. RESULTS We found dose-dependent sex differences in 3β-OH-induced hypnosis and EEG changes. Both male and female rats responded similarly to i.p. 3β-OH 30 mg kg-1. However, at the higher dose (60 mg kg-1, i.p.), female rats had two-fold longer duration of spontaneous immobility than male rats (203.4 [61.6] min vs 101.3 [32.1] min), and their EEG was suppressed in the low-frequency range (2-6 Hz), in contrast to male rats. Although a sex-dependent hypnotic effect was not confirmed after 30 mg kg-1 i.v., female rats appeared more sensitive to 3β-OH with relatively small changes within delta (1-4 Hz) and alpha (8-13 Hz) bands. Finally, 3β-OH had a rapid onset of action and potent hypnotic/anaesthetic effect after 60 mg kg-1 i.v. in rats of both sexes; however, all female rats and only half of the male rats reached burst suppression, an EEG pattern usually associated with profound inhibition of thalamocortical networks. CONCLUSIONS Based on its behavioural effects and EEG signature, 3β-OH is a potent hypnotic in rats, with female rats being more sensitive than male rats.
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Affiliation(s)
- Srdjan M Joksimovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
| | - Dayalan Sampath
- Department of Neuroscience and Experimental Therapeutics, Texas A&M University System, College Station, TX, USA
| | - Kathiresan Krishnan
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO, USA
| | - Douglas F Covey
- Department of Developmental Biology, Washington University School of Medicine, St Louis, MO, USA; Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine, St Louis, MO, USA
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Yogendra H Raol
- Department of Pediatrics, Division of Neurology, Translational Epilepsy Research Program, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Slobodan M Todorovic
- Department of Anesthesiology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA; Neuroscience Graduate Program, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
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Tøttrup L, Atashzar SF, Farina D, Kamavuako EN, Jensen W. Altered evoked low-frequency connectivity from SI to ACC following nerve injury in rats. J Neural Eng 2021; 18. [PMID: 33957613 DOI: 10.1088/1741-2552/abfeb9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/06/2021] [Indexed: 12/11/2022]
Abstract
Objective. Despite decades of research on central processing of pain, there are still several unanswered questions, in particular regarding the brain regions that may contribute to this alerting sensation. Since it is generally accepted that more than one cortical area is responsible for pain processing, there is an increasing focus on the interaction between areas known to be involved.Approach. In this study, we aimed to investigate the bidirectional information flow from the primary somatosensory cortex (SI) to the anterior cingulate cortex (ACC) in an animal model of neuropathic pain.19 rats (nine controls and ten intervention) had an intracortical electrode implanted with six pins in SI and six pins in ACC, and a cuff stimulation electrode around the sciatic nerve. The intervention rats were subjected to the spared nerve injury (SNI) after baseline recordings. Electrical stimulation at three intensities of both noxious and non-noxious stimulation was used to record electrically evoked cortical potentials. To investigate information flow, two connectivity measures were used: phase lag index (PLI) and granger prediction (GP). The rats were anesthetized during the entire study.Main results. Immediately after the intervention (<5 min after intervention), the high frequency (γandγ+) PLI was significantly decreased compared to controls. In the last recording cycle (3-4 h after intervention), the GP increased consistently in the intervention group. Peripheral nerve injury, as a model of neuropathic pain, resulted in an immediate decrease in information flow between SI and ACC, possibly due to decreased sensory input from the injured nerve. Hours after injury, the connectivity between SI and ACC increased, likely indicating hypersensitivity of this pathway.Significance. We have shown that both a directed and non-directed connectivity between SI and ACC approach can be used to show the acute changes resulting from the SNI model.
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Affiliation(s)
- Lea Tøttrup
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - S Farokh Atashzar
- Departments of Electrical and Computer Engineering, and Mechanical and Aerospace Engineering, New York University, New York, NY, USA.,NYU WIRELESS center, New York University (NYU), New York, NY, USA
| | - Dario Farina
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ernest Nlandu Kamavuako
- Department of Engineering, King's College London, London, United Kingdom.,Université de Kindu, Faculté de Médecine, Département des Sciences de base, Maniema, DR Congo
| | - Winnie Jensen
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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Global genetic deletion of Ca V3.3 channels facilitates anaesthetic induction and enhances isoflurane-sparing effects of T-type calcium channel blockers. Sci Rep 2020; 10:21510. [PMID: 33299036 PMCID: PMC7725806 DOI: 10.1038/s41598-020-78488-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 11/13/2020] [Indexed: 01/02/2023] Open
Abstract
We previously documented that the CaV3.3 isoform of T-type calcium channels (T-channels) is inhibited by clinically relevant concentrations of volatile anaesthetics, including isoflurane. However, little is understood about the functional role of CaV3.3 channels in anaesthetic-induced hypnosis and underlying neuronal oscillations. To address this issue, we used CaV3.3 knock-out (KO) mice and a panselective T-channel blocker 3,5-dichloro-N-[1-(2,2-dimethyltetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide (TTA-P2). We found that mutant mice injected with the vehicle showed faster induction of hypnosis than wild-type (WT) mice, while the percent isoflurane at which hypnosis and immobility occurred was not different between two genotypes. Furthermore, we found that TTA-P2 facilitated isoflurane induction of hypnosis in the CaV3.3 KO mice more robustly than in the WT mice. Isoflurane-induced hypnosis following injections of TTA-P2 was accompanied with more prominent delta and theta EEG oscillations in the mutant mice, and reached burst-suppression pattern earlier when compared to the WT mice. Our findings point to a relatively specific value of CaV3.3 channels in anaesthetic induced hypnosis. Furthermore, we propose that T-channel blockers may be further explored as a valuable adjunct to reducing the usage of potent volatile anaesthetics, thereby improving their safety.
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Eagleman SL, Vaughn DA, Drover DR, Drover CM, Cohen MS, Ouellette NT, MacIver MB. Do Complexity Measures of Frontal EEG Distinguish Loss of Consciousness in Geriatric Patients Under Anesthesia? Front Neurosci 2018; 12:645. [PMID: 30294254 PMCID: PMC6158339 DOI: 10.3389/fnins.2018.00645] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 08/29/2018] [Indexed: 12/04/2022] Open
Abstract
While geriatric patients have a high likelihood of requiring anesthesia, they carry an increased risk for adverse cognitive outcomes from its use. Previous work suggests this could be mitigated by better intraoperative monitoring using indexes defined by several processed electroencephalogram (EEG) measures. Unfortunately, inconsistencies between patients and anesthetic agents in current analysis techniques have limited the adoption of EEG as standard of care. In attempts to identify new analyses that discriminate clinically-relevant anesthesia timepoints, we tested 1/f frequency scaling as well as measures of complexity from nonlinear dynamics. Specifically, we tested whether analyses that characterize time-delayed embeddings, correlation dimension (CD), phase-space geometric analysis, and multiscale entropy (MSE) capture loss-of-consciousness changes in EEG activity. We performed these analyses on EEG activity collected from a traditionally hard-to-monitor patient population: geriatric patients on beta-adrenergic blockade who were anesthetized using a combination of fentanyl and propofol. We compared these analyses to traditional frequency-derived measures to test how well they discriminated EEG states before and after loss of response to verbal stimuli. We found spectral changes similar to those reported previously during loss of response. We also found significant changes in 1/f frequency scaling. Additionally, we found that our phase-space geometric characterization of time-delayed embeddings showed significant differences before and after loss of response, as did measures of MSE. Our results suggest that our new spectral and complexity measures are capable of capturing subtle differences in EEG activity with anesthesia administration-differences which future work may reveal to improve geriatric patient monitoring.
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Affiliation(s)
- Sarah L. Eagleman
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
| | - Don A. Vaughn
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, United States
- Department of Psychology, University of Santa Clara, Santa Clara, CA, United States
| | - David R. Drover
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
| | | | - Mark S. Cohen
- UCLA Semel Institute for Neuroscience and Human Behavior, Los Angeles, CA, United States
- UCLA Departments of Psychiatry, Neurology, Radiology, Psychology, Biomedical Physics and Bioengineering, California Nanosystems Institute, Los Angeles, CA, United States
| | - Nicholas T. Ouellette
- Department of Civil and Environmental Engineering, Stanford University, Stanford, CA, United States
| | - M. Bruce MacIver
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Palo Alto, CA, United States
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Choi DH, Shin TJ, Kim S, Bae J, Cho D, Ham J, Park JY, Kim HI, Jeong S, Lee B, Kim JG. Monitoring cerebral oxygenation and local field potential with a variation of isoflurane concentration in a rat model. BIOMEDICAL OPTICS EXPRESS 2016; 7:4114-4124. [PMID: 27867719 PMCID: PMC5102553 DOI: 10.1364/boe.7.004114] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/25/2016] [Accepted: 09/09/2016] [Indexed: 06/06/2023]
Abstract
We aimed to investigate experimentally how anesthetic levels affect cerebral metabolism measured by near-infrared spectroscopy (NIRS) and to identify a robust marker among NIRS parameters to discriminate various stages of anesthetic depth in rats under isoflurane anesthesia. In order to record the hemodynamic changes and local field potential (LFP) in the brain, fiber-optic cannulae and custom-made microelectrodes were implanted in the frontal cortex of the skull. The NIRS and LFP signals were continuously monitored before, during and after isoflurane anesthesia. As isoflurane concentration is reduced, the level of oxyhemoglobin and total hemoglobin concentrations of the frontal cortex decreased gradually, while deoxyhemoglobin increased. The reflectance ratio between 730nm and 850nm and burst suppression ratio (BSR) correspond similarly with the change of oxyhemoglobin during the variation of isoflurane concentration. These results suggest that NIRS signals in addition to EEG may provide a possibility of developing a new anesthetic depth index.
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Affiliation(s)
- Dong-Hyuk Choi
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea; These authors contributed equally to this study
| | - Teo Jeon Shin
- Department of Pediatric Dentistry, School of Dentistry, Seoul National University, Seoul 03080, South Korea; These authors contributed equally to this study
| | - Seonghyun Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Jayyoung Bae
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Dongrae Cho
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Jinsil Ham
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Ji-Young Park
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Hyoung-Ihl Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea
| | - Seongwook Jeong
- Department of Anesthesiology and Pain Medicine, Chonnam National University Medical School, Gwangju 61469, South Korea
| | - Boreom Lee
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea;
| | - Jae Gwan Kim
- Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, South Korea;
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Tajima S, Yanagawa T, Fujii N, Toyoizumi T. Untangling Brain-Wide Dynamics in Consciousness by Cross-Embedding. PLoS Comput Biol 2015; 11:e1004537. [PMID: 26584045 PMCID: PMC4652869 DOI: 10.1371/journal.pcbi.1004537] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 09/07/2015] [Indexed: 12/15/2022] Open
Abstract
Brain-wide interactions generating complex neural dynamics are considered crucial for emergent cognitive functions. However, the irreducible nature of nonlinear and high-dimensional dynamical interactions challenges conventional reductionist approaches. We introduce a model-free method, based on embedding theorems in nonlinear state-space reconstruction, that permits a simultaneous characterization of complexity in local dynamics, directed interactions between brain areas, and how the complexity is produced by the interactions. We demonstrate this method in large-scale electrophysiological recordings from awake and anesthetized monkeys. The cross-embedding method captures structured interaction underlying cortex-wide dynamics that may be missed by conventional correlation-based analysis, demonstrating a critical role of time-series analysis in characterizing brain state. The method reveals a consciousness-related hierarchy of cortical areas, where dynamical complexity increases along with cross-area information flow. These findings demonstrate the advantages of the cross-embedding method in deciphering large-scale and heterogeneous neuronal systems, suggesting a crucial contribution by sensory-frontoparietal interactions to the emergence of complex brain dynamics during consciousness.
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Affiliation(s)
- Satohiro Tajima
- RIKEN Brain Science Institute, Hirosawa, Wako, Saitama, Japan
- Department of Neuroscience, University of Geneva, CMU, Genève, Switzerland
| | - Toru Yanagawa
- RIKEN Brain Science Institute, Hirosawa, Wako, Saitama, Japan
| | - Naotaka Fujii
- RIKEN Brain Science Institute, Hirosawa, Wako, Saitama, Japan
| | - Taro Toyoizumi
- RIKEN Brain Science Institute, Hirosawa, Wako, Saitama, Japan
- Department of Computational Intelligence and Systems Science, Tokyo Institute of Technology, Midori-ku, Yokohama, Kanagawa, Japan
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Vazey EM, Aston-Jones G. Designer receptor manipulations reveal a role of the locus coeruleus noradrenergic system in isoflurane general anesthesia. Proc Natl Acad Sci U S A 2014; 111:3859-64. [PMID: 24567395 PMCID: PMC3956184 DOI: 10.1073/pnas.1310025111] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mechanisms driving emergence from general anesthesia are not well understood. The noradrenergic brain nucleus locus coeruleus (LC) modulates arousal and may have effects on general anesthetic state. Using virally delivered designer receptors to specifically control LC norepinephrine (NE) neurons, we investigated the causal relationship between LC-NE activity and general anesthetic state under isoflurane. Selective activation of LC-NE neurons produced cortical electroencephalography (EEG) activation under continuous deep isoflurane anesthesia. Specifically, LC-NE activation reduced burst suppression in EEG and drove a rightward shift in peak EEG frequency with reduced δ EEG power and increased θ EEG power, measures of cortical arousal. LC-NE activation also accelerated behavioral emergence from deep isoflurane anesthesia; this was prevented with β or α1 noradrenergic antagonists. Moreover, these adrenoreceptor antagonists alone were sufficient to markedly potentiate anesthetic duration when delivered centrally or peripherally. Induction of anesthesia also was retarded by LC-NE activation. Our results demonstrate that the LC-NE system strongly modulates the anesthetic state, and that changes in LC-NE neurotransmission alone can affect the emergence from isoflurane general anesthesia. Taken together, these findings extend our understanding of mechanisms underlying general anesthesia and cortical arousal, and have significant implications for optimizing the clinical safety and management of general anesthesia.
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Affiliation(s)
- Elena M. Vazey
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
| | - Gary Aston-Jones
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
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Kortelainen J, Väyrynen E, Jia X, Seppänen T, Thakor N. EEG-based detection of awakening from isoflurane anesthesia in rats. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2012:4279-82. [PMID: 23366873 DOI: 10.1109/embc.2012.6346912] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In animal studies, reliable measures for depth of anesthesia are frequently required. Previous findings suggest that the continuous depth of anesthesia indices developed for humans might not be adequate for rats whose EEG changes during anesthesia represent more of quick transitions between discrete states. In this paper, the automatic EEG-based detection of awakening from anesthesia was studied in rats. An algorithm based on Bayesian Information Criterion (BIC) is proposed for the assessment of the switch-like change in the signal characteristics occurring just before the awakening. The method was tested with EEGs recorded from ten rats recovering from isoflurane anesthesia. The algorithm was shown to be able to detect the sudden change in the EEG related to the moment of awakening with a precision comparable to careful visual inspection. Our findings suggest that monitoring such signal changes may offer an interesting alternative to the application of continuous depth of anesthesia indices when avoiding the awakening of the animal during e.g. a clinical experiment.
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Affiliation(s)
- Jukka Kortelainen
- Department of Computer Science and Engineering, BOX 4500, FIN-90014 University of Oulu, Finland.
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Electroencephalographic and hypnotic recoveries after brief and prolonged infusions of etomidate and optimized soft etomidate analogs. Anesthesiology 2013; 117:1037-43. [PMID: 22929726 DOI: 10.1097/aln.0b013e31826d3de2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
BACKGROUND Methoxycarbonyl etomidate is the prototypical soft etomidate analog. Because it has relatively low potency and is extremely rapidly metabolized, large quantities must be infused to maintain hypnosis. Consequently with prolonged infusion, metabolite reaches sufficient concentrations to delay recovery. Dimethyl-methoxycarbonyl metomidate (DMMM) and cyclopropyl-methoxycarbonyl metomidate (CPMM) are methoxycarbonyl etomidate analogs with higher potencies and slower clearance. Because of these properties, we hypothesized that dosing would be lower and electroencephalographic and hypnotic recoveries would be faster - and less context-sensitive - with DMMM or CPMM versus methoxycarbonyl etomidate or etomidate. METHODS Etomidate, DMMM, and CPMM where infused into rats (n = 6 per group) for either 5 min or 120 min. After infusion termination, electroencephalographic and hypnotic recovery times were measured. The immobilizing ED50 infusion rates were determined using a tail clamp assay. RESULTS Upon terminating 5-min infusions, electroencephalographic and hypnotic recovery times were not different among hypnotics. However, upon terminating 120-min infusions, recovery times varied significantly with respective values (mean ± SD) 48 ± 13 min and 31 ± 6.5 min (etomidate), 17 ± 7.0 min and 14 ± 3.4 min (DMMM), and 4.5 ± 1.1 min and 4.2 ± 1.6 min (CPMM). The immobilizing ED50 infusion rates were (mean ± SD) 0.19 ± 0.03 mg · kg · min (etomidate), 0.60 ± 0.12 mg · kg · min (DMMM), and 0.89 ± 0.18 mg · kg · min (CPMM). CONCLUSIONS Electroencephalographic and hypnotic recoveries following prolonged infusions of DMMM and CPMM are faster than those following methoxycarbonyl etomidate or etomidate. In the case of CPMM infusion, recovery times are 4 min and context-insensitive.
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Kortelainen J, Jia X, Seppänen T, Thakor N. Increased electroencephalographic gamma activity reveals awakening from isoflurane anaesthesia in rats. Br J Anaesth 2012; 109:782-9. [PMID: 22907339 DOI: 10.1093/bja/aes265] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Animal studies often require reliable measures for anaesthetic drug effects. Lately, EEG-based depth of anaesthesia estimation has been widely applied to rat models. This study investigated the reliability of different EEG spectral properties in revealing awakening from isoflurane anaesthesia in rats. METHODS Adult Wistar rats with previously implanted frontal epidural electrodes were anaesthetized using isoflurane. The anaesthesia was slowly lightened until awakening, as observed by the first spontaneous movement, after which anaesthesia was induced again by increasing the isoflurane concentration. EEG was recorded during the recovery and induction periods, and the spectrograms and 23 quantitative spectral parameters used in the depth of anaesthesia estimation were calculated from the signals. RESULTS The awakening was accompanied by a decrease in EEG activity at frequencies below 25 Hz, while the activity at higher frequencies (25-150 Hz) was increased. Whereas the behaviour of parameters used to measure activity in the lower frequencies was subject to variability between animals, the increase in higher frequency activity was more consistent, resulting in a statistically significant change in the relative gamma power parameters at the moment of awakening. CONCLUSIONS The increase in frontal relative gamma activity, especially in the 50-150 Hz frequency band, seems to be the most reliable EEG indicator for the awakening of a rat from isoflurane anaesthesia. A number of other spectral measures can also be used to detect this event. However, the role of gamma frequencies in the performance of these parameters is crucial.
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Affiliation(s)
- J Kortelainen
- Department of Computer Science and Engineering, University of Oulu, Oulu, Finland.
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Chemali JJ, Wong KFK, Solt K, Brown EN. A state-space model of the burst suppression ratio. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2012; 2011:1431-4. [PMID: 22254587 DOI: 10.1109/iembs.2011.6090354] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Burst suppression is an electroencephalogram pattern observed in states of severely reduced brain activity, such as general anesthesia, hypothermia and anoxic brain injuries. The burst suppression ratio (BSR), defined as the fraction of EEG spent in suppression per epoch, is the standard quantitative measure used to characterize burst suppression. We present a state space model to compute a dynamic estimate of the BSR as the instantaneous probability of suppression. We estimate the model using an approximate EM algorithm and illustrate its application in the analysis of rodent burst suppression recordings under general anesthesia. Our approach removes the need to artificially average the ratio over long epochs and allows us to make formal statistical comparisons of burst activity at different time points. Our state-space model suggests a more principled way to analyze this key EEG feature that may offer more informative assessments of its associated brain state.
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Surrogate data modeling the relationship between high frequency amplitudes and Higuchi fractal dimension of EEG signals in anesthetized rats. J Theor Biol 2011; 289:160-6. [DOI: 10.1016/j.jtbi.2011.08.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 08/25/2011] [Accepted: 08/29/2011] [Indexed: 11/17/2022]
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13
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Effects of isoflurane upon minimum alveolar concentration and cerebral cortex depression in pigs and goats: An interspecies comparison. Vet J 2011; 187:217-20. [DOI: 10.1016/j.tvjl.2009.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 11/12/2009] [Accepted: 11/17/2009] [Indexed: 11/21/2022]
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van Rijn CM, Krijnen H, Menting-Hermeling S, Coenen AML. Decapitation in rats: latency to unconsciousness and the 'wave of death'. PLoS One 2011; 6:e16514. [PMID: 21304584 PMCID: PMC3029360 DOI: 10.1371/journal.pone.0016514] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 01/04/2011] [Indexed: 11/22/2022] Open
Abstract
The question whether decapitation is a humane method of euthanasia in awake animals is being debated. To gather arguments in this debate, obsolete rats were decapitated while recording the EEG, both of awake rats and of anesthetized rats. Following decapitation a fast and global loss of power of the EEG was observed; the power in the 13–100 Hz frequency band, expressing cognitive activity, decreased according to an exponential decay function to half the initial value within 4 seconds. Whereas the pre-decapitation EEG of the anesthetized animals showed a burst suppression pattern quite different from the awake animals, the power in the postdecapitation EEG did not differ between the two groups. This might indicate that either the power of the EEG does not correlate well with consciousness or that consciousness is briefly regained in the anesthetized group after decapitation. Remarkably, after 50 seconds (awake group) or 80 seconds (anesthetized group) following decapitation, a high amplitude slow wave was observed. The EEG before this wave had more power than the signal after the wave. This wave might be due to a simultaneous massive loss of membrane potentials of the neurons. Still functioning ion channels, which keep the membrane potential intact before the wave, might explain the observed power difference. Two conclusions were drawn from this experiment. It is likely that consciousness vanishes within seconds after decapitation, implying that decapitation is a quick and not an inhumane method of euthanasia. It seems that the massive wave which can be recorded approximately one minute after decapitation reflects the ultimate border between life and death. This observation might have implications in the discussions on the appropriate time for organ donation.
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Affiliation(s)
- Clementina M van Rijn
- Department of Biological Psychology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
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15
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The effects of EEG suppression and anesthetics on stimulus thresholds in functional cortical motor mapping. Clin Neurophysiol 2010; 121:784-92. [DOI: 10.1016/j.clinph.2010.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 12/13/2009] [Accepted: 01/03/2010] [Indexed: 11/19/2022]
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Lee U, Mashour GA, Kim S, Noh GJ, Choi BM. Propofol induction reduces the capacity for neural information integration: implications for the mechanism of consciousness and general anesthesia. Conscious Cogn 2008; 18:56-64. [PMID: 19054696 DOI: 10.1016/j.concog.2008.10.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/05/2008] [Accepted: 10/12/2008] [Indexed: 10/21/2022]
Abstract
The cognitive unbinding paradigm suggests that the synthesis of neural information is attenuated by general anesthesia. Here, we analyzed the functional organization of brain activities in the conscious and anesthetized states, based on functional segregation and integration. Electroencephalography (EEG) recordings were obtained from 14 subjects undergoing induction of general anesthesia with propofol. We quantified changes in mean information integration capacity in each band of the EEG. After induction with propofol, mean information integration capacity was reduced most prominently in the gamma band of the EEG (p=.0001). Furthermore, we demonstrate that loss of consciousness is reflected by the breakdown of the spatiotemporal organization of gamma waves. We conclude that induction of general anesthesia with propofol reduces the capacity for information integration in the brain. These data directly support the information integration theory of consciousness and the cognitive unbinding paradigm of general anesthesia.
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Affiliation(s)
- UnCheol Lee
- Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, MI 48109-0048, USA
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Inverse zombies, anesthesia awareness, and the hard problem of unconsciousness. Conscious Cogn 2008; 17:1163-8. [DOI: 10.1016/j.concog.2008.06.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 06/01/2008] [Accepted: 06/05/2008] [Indexed: 11/19/2022]
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Sommers MG, Nguyen NK, Veening JG, Vissers KC, Ritskes-Hoitinga M, van Egmond J. Suppression of Noxious-Induced C-Fos Expression in the Rat Lumbar Spinal Cord by Isoflurane Alone or Combined with Fentanyl. Anesth Analg 2008; 106:1303-8, table of contents. [DOI: 10.1213/ane.0b013e3181678831] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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