101
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Zhou X, Wang Y, Zhang C, Wang M, Zhang M, Yu L, Yan M. The Role of Dopaminergic VTA Neurons in General Anesthesia. PLoS One 2015; 10:e0138187. [PMID: 26398236 PMCID: PMC4580504 DOI: 10.1371/journal.pone.0138187] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 08/27/2015] [Indexed: 01/18/2023] Open
Abstract
Recent studies have demonstrated that the central dopaminergic system is implicated in the mechanism underlying general anesthesia. Here, we investigated whether dopaminergic ventral tegmental area (VTA) neurons participate in general anesthesia. Dopaminergic VTA neurons were selectively ablated from male Sprague Dawley rats via the bilateral infusion of 6-hydroxydopamine (6-OHDA) into the VTA. Two weeks after infusion, the number of dopaminergic neurons in the bilateral VTA was markedly reduced in the 6-OHDA-treated rats compared with the vehicle-treated rats. These bilateral VTA lesions significantly prolonged the recovery time for propofol but did not significantly alter its onset time or 50% effective dose (ED50) value. In addition, the anesthetic responses to isoflurane and ketamine were unaffected by the VTA lesions. Our findings suggested that dopaminergic VTA neurons might be involved in the emergence from propofol anesthesia.
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Affiliation(s)
- Xuelong Zhou
- Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Yin Wang
- Department of Anesthesiology, The Tai Zhou People’s Hospital, Taizhou, 225300, China
| | - Chenjing Zhang
- Department of Gastroenterology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Min Wang
- Jiangsu Key Laboratory of Anesthesiology, Xuzhou Medical College, Xuzhou, 221000, China
| | - Mei Zhang
- Jiangsu Key Laboratory of Anesthesiology, Xuzhou Medical College, Xuzhou, 221000, China
| | - LiNa Yu
- Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310000, China
| | - Min Yan
- Department of Anesthesiology, The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310000, China
- * E-mail:
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102
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Orzeł-Gryglewska J, Matulewicz P, Jurkowlaniec E. Brainstem system of hippocampal theta induction: The role of the ventral tegmental area. Synapse 2015; 69:553-75. [PMID: 26234671 DOI: 10.1002/syn.21843] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 07/03/2015] [Accepted: 07/22/2015] [Indexed: 12/13/2022]
Abstract
This article summarizes the results of studies concerning the influence of the ventral tegmental area (VTA) on the hippocampal theta rhythm. Temporary VTA inactivation resulted in transient loss of the hippocampal theta. Permanent destruction of the VTA caused a long-lasting depression of the power of the theta and it also had some influence on the frequency of the rhythm. Activation of glutamate (GLU) receptors or decrease of GABAergic tonus in the VTA led to enhancement of dopamine release and increased hippocampal theta power. High time and frequency cross-correlation was detected for the theta band between the VTA and hippocampus during paradoxical sleep and active waking. Thus, the VTA may belong to the broad network involved in theta rhythm regulation. This article also presents a model of brainstem-VTA-hippocampal interactions in the induction of the hippocampal theta rhythm. The projections from the VTA which enhance theta rhythm are incorporated into the main theta generation pathway, in which the septum acts as the central node. The neuronal activity that may be responsible for the ability of the VTA to regulate theta probably derives from the structures associated with rapid eye movement (sleep) (REM) sleep or with sensorimotor activity (i.e., mainly from the pedunculopontine and laterodorsal tegmental nuclei and also from the raphe).
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Affiliation(s)
| | - Paweł Matulewicz
- Department of Animal and Human Physiology, University of Gdańsk, Gdańsk, 80-308, Poland
| | - Edyta Jurkowlaniec
- Department of Animal and Human Physiology, University of Gdańsk, Gdańsk, 80-308, Poland
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103
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Dextroamphetamine (but Not Atomoxetine) Induces Reanimation from General Anesthesia: Implications for the Roles of Dopamine and Norepinephrine in Active Emergence. PLoS One 2015; 10:e0131914. [PMID: 26148114 PMCID: PMC4492624 DOI: 10.1371/journal.pone.0131914] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/08/2015] [Indexed: 11/23/2022] Open
Abstract
Methylphenidate induces reanimation (active emergence) from general anesthesia in rodents, and recent evidence suggests that dopaminergic neurotransmission is important in producing this effect. Dextroamphetamine causes the direct release of dopamine and norepinephrine, whereas atomoxetine is a selective reuptake inhibitor for norepinephrine. Like methylphenidate, both drugs are prescribed to treat Attention Deficit Hyperactivity Disorder. In this study, we tested the efficacy of dextroamphetamine and atomoxetine for inducing reanimation from general anesthesia in rats. Emergence from general anesthesia was defined by return of righting. During continuous sevoflurane anesthesia, dextroamphetamine dose-dependently induced behavioral arousal and restored righting, but atomoxetine did not (n = 6 each). When the D1 dopamine receptor antagonist SCH-23390 was administered prior to dextroamphetamine under the same conditions, righting was not restored (n = 6). After a single dose of propofol (8 mg/kg IV), the mean emergence times for rats that received normal saline (vehicle) and dextroamphetamine (1 mg/kg IV) were 641 sec and 404 sec, respectively (n = 8 each). The difference was statistically significant. Although atomoxetine reduced mean emergence time to 566 sec (n = 8), this decrease was not statistically significant. Spectral analysis of electroencephalogram recordings revealed that dextroamphetamine and atomoxetine both induced a shift in peak power from δ (0.1–4 Hz) to θ (4–8 Hz) during continuous sevoflurane general anesthesia, which was not observed when animals were pre-treated with SCH-23390. In summary, dextroamphetamine induces reanimation from general anesthesia in rodents, but atomoxetine does not induce an arousal response under the same experimental conditions. This supports the hypothesis that dopaminergic stimulation during general anesthesia produces a robust behavioral arousal response. In contrast, selective noradrenergic stimulation causes significant neurophysiological changes, but does not promote behavioral arousal during general anesthesia. We hypothesize that dextroamphetamine is more likely than atomoxetine to be clinically useful for restoring consciousness in anesthetized patients, mainly due to its stimulation of dopaminergic neurotransmission.
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104
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The 9th International Symposium on Memory and Awareness in Anesthesia (MAA9). Br J Anaesth 2015. [DOI: 10.1093/bja/aev204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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105
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Pillay S, Liu X, Baracskay P, Hudetz AG. Brainstem stimulation increases functional connectivity of basal forebrain-paralimbic network in isoflurane-anesthetized rats. Brain Connect 2015; 4:523-34. [PMID: 25090190 DOI: 10.1089/brain.2014.0254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Brain states and cognitive-behavioral functions are precisely controlled by subcortical neuromodulatory networks. Manipulating key components of the ascending arousal system (AAS), via deep-brain stimulation, may help facilitate global arousal in anesthetized animals. Here we test the hypothesis that electrical stimulation of the oral part of the pontine reticular nucleus (PnO) under light isoflurane anesthesia, associated with loss of consciousness, leads to cortical desynchronization and specific changes in blood-oxygenation-level-dependent (BOLD) functional connectivity (FC) of the brain. BOLD signals were acquired simultaneously with frontal epidural electroencephalogram before and after PnO stimulation. Whole-brain FC was mapped using correlation analysis with seeds in major centers of the AAS. PnO stimulation produced cortical desynchronization, a decrease in δ- and θ-band power, and an increase in approximate entropy. Significant increases in FC after PnO stimulation occurred between the left nucleus Basalis of Meynert (NBM) as seed and numerous regions of the paralimbic network. Smaller increases in FC were present between the central medial thalamic nucleus and retrosplenium seeds and the left caudate putamen and NBM. The results suggest that, during light anesthesia, PnO stimulation preferentially modulates basal forebrain-paralimbic networks. We speculate that this may be a reflection of disconnected awareness.
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Affiliation(s)
- Siveshigan Pillay
- 1 Department of Anesthesiology, Medical College of Wisconsin , Milwaukee, Wisconsin
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106
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Akeju O, Loggia ML, Catana C, Pavone KJ, Vazquez R, Rhee J, Contreras Ramirez V, Chonde DB, Izquierdo-Garcia D, Arabasz G, Hsu S, Habeeb K, Hooker JM, Napadow V, Brown EN, Purdon PL. Disruption of thalamic functional connectivity is a neural correlate of dexmedetomidine-induced unconsciousness. eLife 2014; 3:e04499. [PMID: 25432022 PMCID: PMC4280551 DOI: 10.7554/elife.04499] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 11/26/2014] [Indexed: 12/17/2022] Open
Abstract
Understanding the neural basis of consciousness is fundamental to neuroscience research. Disruptions in cortico-cortical connectivity have been suggested as a primary mechanism of unconsciousness. By using a novel combination of positron emission tomography and functional magnetic resonance imaging, we studied anesthesia-induced unconsciousness and recovery using the α2-agonist dexmedetomidine. During unconsciousness, cerebral metabolic rate of glucose and cerebral blood flow were preferentially decreased in the thalamus, the Default Mode Network (DMN), and the bilateral Frontoparietal Networks (FPNs). Cortico-cortical functional connectivity within the DMN and FPNs was preserved. However, DMN thalamo-cortical functional connectivity was disrupted. Recovery from this state was associated with sustained reduction in cerebral blood flow and restored DMN thalamo-cortical functional connectivity. We report that loss of thalamo-cortical functional connectivity is sufficient to produce unconsciousness. DOI:http://dx.doi.org/10.7554/eLife.04499.001 Although we are all familiar with the experience of being conscious, explaining precisely what consciousness is and how it arises from activity in the brain remains extremely challenging. Indeed, explaining consciousness is so challenging that it is sometimes referred to as ‘the hard question’ of neuroscience. One way to obtain insights into the neural basis of consciousness is to compare patterns of activity in the brains of conscious subjects with patterns of brain activity in the same subjects under anesthesia. The results of some experiments of this kind suggest that loss of consciousness occurs when the communication between specific regions within the outer layer of the brain, the cortex, is disrupted. However, other studies seem to contradict these findings by showing that this communication can sometimes remain intact in unconscious subjects. Akeju, Loggia et al. have now resolved this issue by using brain imaging to examine the changes that occur as healthy volunteers enter and emerge from a light form of anesthesia roughly equivalent to non-REM sleep. An imaging technique called PET revealed that the loss of consciousness in the subjects was accompanied by reduced activity in a structure deep within the brain called the thalamus. Reduced activity was also seen in areas of cortex at the front and back of the brain. A technique called fMRI showed in turn that communication between the cortex and the thalamus was disrupted as subjects drifted into unconsciousness, whereas communication between cortical regions was spared. As subjects awakened from the anesthesia, communication between the thalamus and the cortex was restored. These results suggest that changes within distinct brain regions give rise to different depths of unconsciousness. Loss of communication between the thalamus and the cortex generates the unconsciousness of sleep or light anesthesia, while the additional loss of communication between cortical regions generates the unconsciousness of general anesthesia or coma. In addition to explaining the mixed results seen in previous experiments, this distinction could lead to advances in the diagnosis of patients with disorders of consciousness, and even to the development of therapies that target the thalamus and its connections with cortex. DOI:http://dx.doi.org/10.7554/eLife.04499.002
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Affiliation(s)
- Oluwaseun Akeju
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Marco L Loggia
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Ciprian Catana
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Kara J Pavone
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Rafael Vazquez
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - James Rhee
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Violeta Contreras Ramirez
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Daniel B Chonde
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - David Izquierdo-Garcia
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Grae Arabasz
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Shirley Hsu
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Kathleen Habeeb
- Clinical Research Center, Massachusetts General Hospital, Boston, United States
| | - Jacob M Hooker
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Vitaly Napadow
- MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Charlestown, United States
| | - Emery N Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
| | - Patrick L Purdon
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, United States
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107
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Raz A, Grady SM, Krause BM, Uhlrich DJ, Manning KA, Banks MI. Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex. Front Syst Neurosci 2014; 8:191. [PMID: 25339873 PMCID: PMC4188029 DOI: 10.3389/fnsys.2014.00191] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 09/18/2014] [Indexed: 12/31/2022] Open
Abstract
The mechanism of loss of consciousness (LOC) under anesthesia is unknown. Because consciousness depends on activity in the cortico-thalamic network, anesthetic actions on this network are likely critical for LOC. Competing theories stress the importance of anesthetic actions on bottom-up “core” thalamo-cortical (TC) vs. top-down cortico-cortical (CC) and matrix TC connections. We tested these models using laminar recordings in rat auditory cortex in vivo and murine brain slices. We selectively activated bottom-up vs. top-down afferent pathways using sensory stimuli in vivo and electrical stimulation in brain slices, and compared effects of isoflurane on responses evoked via the two pathways. Auditory stimuli in vivo and core TC afferent stimulation in brain slices evoked short latency current sinks in middle layers, consistent with activation of core TC afferents. By contrast, visual stimuli in vivo and stimulation of CC and matrix TC afferents in brain slices evoked responses mainly in superficial and deep layers, consistent with projection patterns of top-down afferents that carry visual information to auditory cortex. Responses to auditory stimuli in vivo and core TC afferents in brain slices were significantly less affected by isoflurane compared to responses triggered by visual stimuli in vivo and CC/matrix TC afferents in slices. At a just-hypnotic dose in vivo, auditory responses were enhanced by isoflurane, whereas visual responses were dramatically reduced. At a comparable concentration in slices, isoflurane suppressed both core TC and CC/matrix TC responses, but the effect on the latter responses was far greater than on core TC responses, indicating that at least part of the differential effects observed in vivo were due to local actions of isoflurane in auditory cortex. These data support a model in which disruption of top-down connectivity contributes to anesthesia-induced LOC, and have implications for understanding the neural basis of consciousness.
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Affiliation(s)
- Aeyal Raz
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Anesthesiology, Rabin Medical Center, Petah-Tikva, Israel, Affiliated with Sackler School of Medicine, Tel Aviv University Tel Aviv, Israel
| | - Sean M Grady
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA
| | - Bryan M Krause
- Neuroscience Training Program, University of Wisconsin Madison, WI, USA
| | - Daniel J Uhlrich
- Department of Neuroscience, University of Wisconsin Madison, WI, USA
| | - Karen A Manning
- Department of Neuroscience, University of Wisconsin Madison, WI, USA
| | - Matthew I Banks
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin Madison, WI, USA ; Department of Neuroscience, University of Wisconsin Madison, WI, USA
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108
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Neuromodulation of the conscious state following severe brain injuries. Curr Opin Neurobiol 2014; 29:172-7. [PMID: 25285395 DOI: 10.1016/j.conb.2014.09.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/16/2014] [Accepted: 09/22/2014] [Indexed: 11/22/2022]
Abstract
Disorders of consciousness (DOC) following severe structural brain injuries globally affect the conscious state and the expression of goal-directed behaviors. In some subjects, neuromodulation with medications or electrical stimulation can markedly improve the impaired conscious state present in DOC. We briefly review recent studies and provide an organizing framework for considering the apparently widely disparate collection of medications and approaches that may modulate the conscious state in subjects with DOC. We focus on neuromodulation of the anterior forebrain mesocircuit in DOC and briefly compare mechanisms supporting recovery from structural brain injuries to those underlying facilitated emergence from unconsciousness produced by anesthesia. We derive some general principles for approaching the problem of restoration of consciousness after severe structural brain injuries, and suggest directions for future research.
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109
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Chander D, García PS, MacColl JN, Illing S, Sleigh JW. Electroencephalographic variation during end maintenance and emergence from surgical anesthesia. PLoS One 2014; 9:e106291. [PMID: 25264892 PMCID: PMC4180055 DOI: 10.1371/journal.pone.0106291] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 07/29/2014] [Indexed: 12/16/2022] Open
Abstract
The re-establishment of conscious awareness after discontinuing general anesthesia has often been assumed to be the inverse of loss of consciousness. This is despite the obvious asymmetry in the initiation and termination of natural sleep. In order to characterize the restoration of consciousness after surgery, we recorded frontal electroencephalograph (EEG) from 100 patients in the operating room during maintenance and emergence from general anesthesia. We have defined, for the first time, 4 steady-state patterns of anesthetic maintenance based on the relative EEG power in the slow-wave (<14 Hz) frequency bands that dominate sleep and anesthesia. Unlike single-drug experiments performed in healthy volunteers, we found that surgical patients exhibited greater electroencephalographic heterogeneity while re-establishing conscious awareness after drug discontinuation. Moreover, these emergence patterns could be broadly grouped according to the duration and rapidity of transitions amongst these slow-wave dominated brain states that precede awakening. Most patients progressed gradually from a pattern characterized by strong peaks of delta (0.5-4 Hz) and alpha/spindle (8-14 Hz) power ('Slow-Wave Anesthesia') to a state marked by low delta-spindle power ('Non Slow-Wave Anesthesia') before awakening. However, 31% of patients transitioned abruptly from Slow-Wave Anesthesia to waking; they were also more likely to express pain in the post-operative period. Our results, based on sleep-staging classification, provide the first systematized nomenclature for tracking brain states under general anesthesia from maintenance to emergence, and suggest that these transitions may correlate with post-operative outcomes such as pain.
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Affiliation(s)
- Divya Chander
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California, United States of America
| | - Paul S. García
- Department of Anesthesiology, Atlanta VA Medical Center/Emory University, Atlanta, Georgia, United States of America
| | - Jono N. MacColl
- Department of Anaesthesia, Waikato Clinical School, University of Auckland, Hamilton, New Zealand
| | - Sam Illing
- Department of Anaesthesia, Waikato Clinical School, University of Auckland, Hamilton, New Zealand
| | - Jamie W. Sleigh
- Department of Anaesthesia, Waikato Clinical School, University of Auckland, Hamilton, New Zealand
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