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Palanca BJA, Conway CR, Zeffiro T, Gott BM, Nguyen T, Janski A, Jain N, Komen H, Burke BA, Zorumski CF, Nagele P. Persistent Brain Connectivity Changes in Healthy Volunteers Following Nitrous Oxide Inhalation. BIOLOGICAL PSYCHIATRY GLOBAL OPEN SCIENCE 2023; 3:698-704. [PMID: 37881568 PMCID: PMC10593877 DOI: 10.1016/j.bpsgos.2023.01.006] [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: 01/09/2022] [Revised: 01/15/2022] [Accepted: 01/23/2023] [Indexed: 02/05/2023] Open
Abstract
Background Nitrous oxide holds promise in the treatment of major depressive disorder. Its psychotropic effects and NMDA receptor antagonism have led to comparisons with ketamine. Despite longstanding use, persistent effects of nitrous oxide on the brain have not been characterized. Methods Sixteen healthy volunteers were recruited in a double-blind crossover study. In randomized order, individuals underwent a 1-hour inhalation of either 50% nitrous oxide/oxygen or air/oxygen mixtures. At least two 7.5-minute echo-planar resting-state functional magnetic resonance imaging scans were obtained before and at 2 and 24 hours after each inhalation (average 130 min/participant). Using the time series of preprocessed, motion artifact-scrubbed, and nuisance covariate-regressed imaging data, interregional signal correlations were measured and converted to T scores. Hierarchical clustering and linear mixed-effects models were employed. Results Nitrous oxide inhalation produced changes in global brain connectivity that persisted in the occipital cortex at 2 and 24 hours postinhalation (p < .05, false discovery rate-corrected). Analysis of resting-state networks demonstrated robust strengthening of connectivity between regions of the visual network and those of the dorsal attention network, across 2 and 24 hours after inhalation (p < .05, false discovery rate-corrected). Weaker changes in connectivity were found between the visual cortex and regions of the frontoparietal and default mode networks. Parallel analyses following air/oxygen inhalation yielded no significant changes in functional connectivity. Conclusions Nitrous oxide inhalation in healthy volunteers revealed persistent increases in global connectivity between regions of primary visual cortex and dorsal attention network. These findings suggest that nitrous oxide inhalation induces neurophysiological cortical changes that persist for at least 24 hours.
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Affiliation(s)
- Ben Julian A. Palanca
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri
- Division of Biology and Biomedical Sciences, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Center on Biological Rhythms and Sleep, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Charles R. Conway
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Thomas Zeffiro
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Britt M. Gott
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
- Neuroimaging Labs Research Center, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Thomas Nguyen
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Alvin Janski
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Nisha Jain
- Department of Anesthesia and Critical Care, University of Chicago Medicine, Chicago, Illinois
| | - Helga Komen
- Department of Anesthesiology, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Broc A. Burke
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Charles F. Zorumski
- Department of Psychiatry and Taylor Family Institute for Innovative Psychiatric Research, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Peter Nagele
- Department of Anesthesia and Critical Care, University of Chicago Medicine, Chicago, Illinois
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Timmermann L, Butz M, Gross J, Kircheis G, Häussinger D, Schnitzler A. Neural synchronization in hepatic encephalopathy. Metab Brain Dis 2005; 20:337-46. [PMID: 16382344 DOI: 10.1007/s11011-005-7916-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Hepatic encephalopathy (HE) is clinically characterized by a large variety of symptoms including motor symptoms, cognitive deficits, as well as changes in the level of alertness up to hepatic coma. A number of pathological processes affecting glial and neuronal function have been identified, including hyper-ammonia, changes within the excitatory and inhibitory transmitter systems, as well as osmolytic changes with consecutive cell swelling. One explanation how these pathological processes result in neurological deficits in HE is the concept of pathologically synchronized oscillations within and between relevant brain regions. A number of studies suggest that the cognitive deficits and the reduced level of alertness in patients with HE can be attributed to a significantly slowed and pathologically synchronized spontaneous oscillatory brain activity, depending on the grade of HE. Moreover, HE motor symptoms, like postural tremor called"mini asterixis," have recently been shown to be associated with abnormal thalamo-cortical and cortico-muscular synchronization. Indirect evidence exists from studies of processing and recognition of flicker stimuli that in HE slowing of oscillations also occurs in the visual system. Taken together, pathological synchronization of neuronal activity may turn out to be a promising pathophysiological concept for linking neuronal dysfunction to the diversity of clinical deficits in HE.
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Affiliation(s)
- Lars Timmermann
- Department of Neurology, University Hospital Düsseldorf, Heinrich-Heine University, Düsseldorf, Germany
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Rabat A, Hardouin J, Courtière A. Nitrous oxide impairs selective stages of working memory in rats. Neurosci Lett 2004; 364:22-6. [PMID: 15193748 DOI: 10.1016/j.neulet.2004.03.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2004] [Revised: 03/19/2004] [Accepted: 03/26/2004] [Indexed: 11/25/2022]
Abstract
Working memory impairment under narcosis has never been investigated. Furthermore, mechanisms by which narcosis disturbs working memory processes remain relatively unknown. The present work was aimed at answering to these two questions using a well-known normobaric narcotic gas, nitrous oxide (N2O), and a classical working memory task (a two-trial recognition memory task). Ten Long-Evans rats were tested in this behavioral task under nitrous oxide exposure. The results showed (i) a dose-related impairment of working memory, (ii) a selective effect of N2O on two out of three mnemonic processes: acquisition, and retention, and (iii) a compensatory effect of increasing the acquisition phase duration on these impairments. These results, as previously suggested for long-term memory, agree with the fact that nitrous oxide disrupts in a dose-related manner working memory by notably slowing down acquisition processes.
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Affiliation(s)
- Arnaud Rabat
- Laboratoire de Physiopathologie du comportement, INSERM Unité 588, Institut François Magendie, 1 rue Camille Saint Saëns, 33077 Bordeaux Cedex, France
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Lichtor JL, Lane BS, Zimmerman MB. Residual sleepiness after N2O sedation: a randomized control trial [ISRCTN88442975]. BMC Anesthesiol 2004; 4:5. [PMID: 15140266 PMCID: PMC419701 DOI: 10.1186/1471-2253-4-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2003] [Accepted: 05/12/2004] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND: Nitrous oxide (N2O) provides sedation for procedures that result in constant low-intensity pain. How long do individuals remain sleepy after receiving N2O? We hypothesized that drug effects would be apparent for an hour or more. METHODS: This was a randomized, double blind controlled study. On three separate occasions, volunteers (N = 12) received 100% oxygen or 20% or 40% N2O for 30 min. Dependent measures included the multiple sleep latency test (MSLT), a Drug Effects/Liking questionnaire, visual analogue scales, and five psychomotor tests. Repeated measures analysis of variance was performed with drug and time as factors. RESULTS: During inhalation, drug effects were apparent based on the questionnaire, visual analogue scales, and psychomotor tests. Three hours after inhaling 100% oxygen or 20% N2O, subjects were sleepier than if they breathed 40% N2O. No other drug effects were apparent 1 hour after inhalation ceased. Patients did not demonstrate increased sleepiness after N2O inhalation. CONCLUSION: We found no evidence for increased sleepiness greater than 1 hour after N2O inhalation. Our study suggests that long-term effects of N2O are not significant.
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Affiliation(s)
- J Lance Lichtor
- University of Iowa, Department of Anesthesia, 200 Hawkins Drive, 6 JCP, Iowa City, IA 52242-1079
| | - Bradford S Lane
- University of Chicago, Department of Anesthesia and Critical Care, 5841 S. Maryland Ave, Chicago, IL 60637
| | - M Bridget Zimmerman
- University of Iowa, Department of Biostatistics, 200 Hawkins Drive, C22-E GH, Iowa City, IA 52242
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Bedi A, McCarroll C, Murray JM, Stevenson MA, Fee JPH. The effects of subanaesthetic concentrations of xenon in volunteers. Anaesthesia 2002; 57:233-41. [PMID: 11879212 DOI: 10.1046/j.0003-2409.2001.02455.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study reports the subjective, psychomotor and physiological properties of subanaesthetic concentrations of xenon. Ten healthy male volunteers received either xenon or nitrous oxide in a randomised crossover study design. The subjects breathed either xenon (Xe) or nitrous oxide (N2O) from a closed circuit breathing system, according to a randomised, double-blind protocol. The concentration of xenon required to produce sedation, ranged between 27 and 45% (median 35%). All subjects completed the xenon protocol. Subjects were tested using the Critical Flicker Fusion test and derived electroencephalogram parameters, however, neither test was found to reliably predict sedation. The respiratory rate decreased markedly during sedation with xenon. The subjects did not experience any airway irritability (coughing, breath-holding or laryngospasm) during administration of either gas. One subject required anti-emetic treatment in the N2O group compared to none in the Xe group. Eight subjects reported that they found sedation with xenon pleasant and preferable to nitrous oxide. Xenon sedation was well tolerated and was not associated with any adverse physiological effects, however, it was reported to be subjectively dissimilar to nitrous oxide.
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Affiliation(s)
- A Bedi
- The Department of Anaesthetics and Intensive Care Medicine, The Queen's University of Belfast, Northern Ireland.
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Maier S, Heinrichs W. Nitrous oxide in abdominal surgery. Best Pract Res Clin Anaesthesiol 2001. [DOI: 10.1053/bean.2001.0173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lotze M, Treutwein B, Roenneberg T. Daily rhythm of vigilance assessed by temporal resolution of the visual system. Vision Res 2001; 40:3467-73. [PMID: 11115673 DOI: 10.1016/s0042-6989(00)00175-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To assess the daily distribution of temporal resolution in visual detection, binocular double-pulse resolution (DPR) was measured over a 24 h period in six healthy subjects. DPR showed a significant daily variation with an amplitude for the foveal stimulus of up to 60%. Like in other vigilance-dependent daily rhythms, optimal performance occurred around midday. The DPR measurements described here are an excellent method for assessment of vigilance and mental alertness (e.g. in pharmacological studies). They show strong time-of-day differences, are highly reliable across successive measurements, and can be fully automated.
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Affiliation(s)
- M Lotze
- Institut für Medizinische Psychologie und Verhaltensneurobiologie, Eberhard-Karls-Universität Tübingen, Gartenstrasse 29 D-72074 Tübingen, Germany
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