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Blanco-Hernández E, Balsamo G, Preston-Ferrer P, Burgalossi A. Sensory and behavioral modulation of thalamic head-direction cells. Nat Neurosci 2024; 27:28-33. [PMID: 38177338 DOI: 10.1038/s41593-023-01506-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 10/24/2023] [Indexed: 01/06/2024]
Abstract
Head-direction (HD) neurons are thought to exclusively encode directional heading. In awake mice, we found that sensory stimuli evoked robust short-latency responses in thalamic HD cells, but not in non-HD neurons. The activity of HD cells, but not that of non-HD neurons, was tightly correlated to brain-state fluctuations and dynamically modulated during social interactions. These data point to a new role for the thalamic compass in relaying sensory and behavioral-state information.
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Affiliation(s)
- Eduardo Blanco-Hernández
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany
| | - Giuseppe Balsamo
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany
- Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany
- Graduate Training Centre of Neuroscience, IMPRS, Tübingen, Germany
| | - Patricia Preston-Ferrer
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.
- Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany.
| | - Andrea Burgalossi
- Institute of Neurobiology, University of Tübingen, Tübingen, Germany.
- Werner-Reichardt Centre for Integrative Neuroscience, Tübingen, Germany.
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He J, Zhang H, Dang Y, Zhuang Y, Ge Q, Yang Y, Xu L, Xia X, Laureys S, Yu S, Zhang W. Electrophysiological characteristics of CM-pf in diagnosis and outcome of patients with disorders of consciousness. Brain Stimul 2023; 16:1522-1532. [PMID: 37778457 DOI: 10.1016/j.brs.2023.09.021] [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: 01/11/2023] [Revised: 09/07/2023] [Accepted: 09/20/2023] [Indexed: 10/03/2023] Open
Abstract
BACKGROUND Deep brain stimulation (DBS) in the centromedian-parafascicular complex (CM-pf) has been reported as a potential therapeutic option for disorders of consciousness (DoC). However, the lack of understanding of its electrophysiological characteristics limits the improvement of therapeutic effect. OBJECTIVE To investigate the CM-pf electrophysiological characteristics underlying disorders of consciousness (DoC) and its recovery. METHODS We collected the CM-pf electrophysiological signals from 23 DoC patients who underwent central thalamus DBS (CT-DBS) surgery. Five typical electrophysiological features were extracted, including neuronal firing properties, multiunit activity (MUA) properties, signal stability, spike-MUA synchronization strength (syncMUA), and the background noise level. Their correlations with the consciousness level, the outcome, and the primary clinical factors of DoC were analyzed. RESULTS 11 out of 23 patients (0/2 chronic coma, 5/13 unresponsive wakefulness syndrome/vegetative state (UWS/VS), 6/8 minimally conscious state minus (MCS-)) exhibited an improvement in the level of consciousness after CT-DBS. In CM-pf, significantly stronger gamma band syncMUA strength and alpha band normalized MUA power were found in MCS- patients. In addition, higher firing rates, stronger high-gamma band MUA power and alpha band normalized power, and more stable theta oscillation were correlated with better outcomes. Besides, we also identified electrophysiological properties that are correlated with clinical factors, including etiologies, age, and duration of DoC. CONCLUSION We provide comprehensive analyses of the electrophysiological characteristics of CM-pf in DoC patients. Our results support the 'mesocircuit' hypothesis, one proposed mechanism of DoC recovery, and reveal CM-pf electrophysiological features that are crucial for understanding the pathogenesis of DoC, predicting its recovery, and explaining the effect of clinical factors on DoC.
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Affiliation(s)
- Jianghong He
- Neurosurgery Center, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, China; Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Haoran Zhang
- Laboratory of Brain Atlas and Brain-inspired Intelligence, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, China; School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuanyuan Dang
- Department of Neurosurgery, The First Medical Center of Chinese PLA General Hospital, Beijing, 100853, China
| | - Yutong Zhuang
- Department of Neurosurgery, The Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Qianqian Ge
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Yi Yang
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Long Xu
- Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
| | - Xiaoyu Xia
- Department of Neurosurgery, The Seventh Medical Center of PLA General Hospital, Beijing, 100700, China
| | - Steven Laureys
- CERVO Brain Research Centre, Laval University, Canada; Coma Science Group, GIGA Consciousness Research Unit, Liège University Hospital, Belgium; International Consciousness Science Institute, Hangzhou Normal University, Hangzhou, Zhejiang, China
| | - Shan Yu
- Laboratory of Brain Atlas and Brain-inspired Intelligence, Institute of Automation, Chinese Academy of Sciences, Beijing, 100190, China; School of Future Technology, University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Wangming Zhang
- Neurosurgery Center, The National Key Clinical Specialty, The Engineering Technology Research Center of Education Ministry of China on Diagnosis and Treatment of Cerebrovascular Disease, Guangdong Provincial Key Laboratory on Brain Function Repair and Regeneration, The Neurosurgery Institute of Guangdong Province, Zhujiang Hospital, Southern Medical University, China.
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Effects of ketamine on voltage-gated sodium channels in the barrel cortex and the ventral posteromedial nucleus slices of rats. Neuroreport 2020; 30:1197-1204. [PMID: 31568204 PMCID: PMC6855387 DOI: 10.1097/wnr.0000000000001344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Ketamine is commonly used as a dissociative anesthetic with unique actions in the central nervous system. Previous studies have found that the thalamocortical systems play an important role in general anesthetics induced unconsciousness. Whether the voltage-gated sodium channels in the thalamocortical systems are the target of ketamine remain unclear. The present study used a whole-cell patch-clamp technique to observe the effects of ketamine on voltage-gated Na channels in thalamocortical pyramidal neurons. We found that IC50 of ketamine on Na currents in the primary somatosensory barrel cortex pyramidal neurons and the thalamus ventral posteromedial nucleus pyramidal neurons was 686.72 ± 39.92 and 842.65 ± 87.28 μM, respectively. Ketamine accelerated the Na channels inactivation and slowed inactivation of Na channels after recovery but did not affect the activation. We demonstrated the detailed suppression process of neural voltage-gated Na channels by ketamine on thalamocortical slice. This may provide a new insight into the mechanical explanation for the ketamine anesthesia.
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Malekmohammadi M, Price CM, Hudson AE, DiCesare JAT, Pouratian N. Propofol-induced loss of consciousness is associated with a decrease in thalamocortical connectivity in humans. Brain 2020; 142:2288-2302. [PMID: 31236577 DOI: 10.1093/brain/awz169] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 03/25/2019] [Accepted: 04/18/2019] [Indexed: 11/14/2022] Open
Abstract
Although the molecular effects of many anaesthetics have been well characterized, a network-level explanation for how these changes lead to loss of consciousness remains unclear. Studies using electroencephalography have characterized changes in neural oscillations in the cortex at specific frequency bands during propofol-induced anaesthesia and modelling work suggests these changes result from changes in thalamocortical functional connectivity. However, it is unclear if the neurophysiological changes seen at the cortex are due to enhanced or disrupted thalamocortical communication. Direct recordings from these sites during anaesthesia that could be used to confirm such models are rare. We recorded local field potentials from the ventral intermediate nucleus of the thalamus and electrocorticography signals from the ipsilateral sensorimotor cortex in 10 patients undergoing deep brain stimulation surgery. Signals were acquired during induction of propofol anaesthesia while subjects were resting. After confirming direct structural connectivity between the thalamus and the cortical recording site, we investigated propofol-associated changes in thalamic and cortical local power as well as thalamocortical functional connectivity, as measured with coherence, debiased weighted phase lag index, and phase amplitude coupling. Propofol anaesthesia resulted in local power increases at α frequencies (8-12 Hz) across both thalamic and cortical areas. At sensorimotor cortices, there was a broadband power increase (12-100 Hz), while the power of this same broad frequency band was suppressed within the thalamus. Despite the increase in local α power both within the thalamus and cortex, thalamocortical coherence and debiased weighted phase lag index in the α/low β frequencies (8-16 Hz, which was present in the awake state) significantly decreased with propofol administration (P < 0.05, two group test of coherence). Likewise, propofol administration resulted in decreased phase amplitude coupling between the phase of α/low β in the thalamus and the amplitude of broadband gamma (50-200 Hz) in the cortex (P = 0.031, Wilcoxon signed-rank test). We also report phase amplitude coupling between the phase of slow wave oscillations (0.1-1 Hz) and amplitude of broadband frequencies (8-200 Hz) within the cortex and across thalamocortical connections, during anaesthesia, both following a peak-max pattern. While confirming α-power increases with propofol administration both in thalamus and cortex, we observed decreased thalamocortical connectivity, contradicting models that suggest increasing cortical low frequency power is necessarily related to increased thalamocortical coherence but in support of the theory that propofol-induced loss of consciousness is associated with disrupted thalamocortical communication.
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Affiliation(s)
| | - Collin M Price
- Department of Neurosurgery, University of California, Los Angeles, CA, USA
| | - Andrew E Hudson
- Department of Anaesthesiology, University of California, Los Angeles, CA, USA
| | | | - Nader Pouratian
- Department of Neurosurgery, University of California, Los Angeles, CA, USA
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Zhang Y, Liu C, Zhang L, Zhou W, Yu S, Yi R, Luo D, Fu X. Effects of Propofol on Electrical Synaptic Strength in Coupling Reticular Thalamic GABAergic Parvalbumin-Expressing Neurons. Front Neurosci 2020; 14:364. [PMID: 32410945 PMCID: PMC7198707 DOI: 10.3389/fnins.2020.00364] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 03/25/2020] [Indexed: 12/17/2022] Open
Abstract
Electrical synapses between neurons exhibit a high degree of plasticity, which makes critical contributions to neuronal communication. The GABAergic parvalbumin-expressing (PV+) neurons in the thalamic reticular nucleus (TRN) interact with each other through electrical and chemical synapses. Plasticity of electrical synaptic transmission in TRN plays a key role in regulating thalamocortical and corticothalamic circuits and even the formation of consciousness. We here examined the effects of propofol, a commonly used general anesthetic agent, on the strength of electrical synapses between TRN PV+ neurons by fluorescence-guided patch-clamp recording and pharmacological methods. Results show that 100 μM propofol reduced the electrical synaptic strength between TRN PV+ neurons. Notably, the propofol-induced depression of electrical synaptic strength between TRN PV+ neurons was diminished by saclofen (10 μM, antagonist of GABAB receptors), but not blocked by gabazine (10 μM, antagonist of GABAA receptors). Application of baclofen (10 μM, agonist of GABAB receptors), similar to propofol, also reduced the electrical synaptic strength between TRN PV+ neurons. Moreover, the propofol-induced depression of electrical synaptic strength between TRN PV+ neurons was abolished by 9-CPA (100 μM, specific adenylyl cyclase inhibitor), and by KT5720 (1 μM, selective inhibitor of PKA). Our findings indicate that propofol acts on metabotropic GABAB receptors, resulting in a depression of electrical synaptic transmission of coupled TRN PV+ neurons, which is mediated by the adenylyl cyclase-cAMP-PKA signaling pathway. Our findings also imply that propofol may change the thalamocortical communication via inducing depression of electrical synaptic strength in the TRN.
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Affiliation(s)
- Yu Zhang
- Department of Anesthesiology, Affiliated Hospital of Zunyi Medical University, Guizhou, China.,Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Chengxi Liu
- Guizhou Key Laboratory of Brain Science, Zunyi Medical University, Guizhou, China
| | - Lin Zhang
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Wenjing Zhou
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Shouyang Yu
- Guizhou Key Laboratory of Brain Science, Zunyi Medical University, Guizhou, China
| | - Rulan Yi
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Dan Luo
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical University, Guizhou, China
| | - Xiaoyun Fu
- Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical University, Guizhou, China
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Abstract
PURPOSE The reliability of somatosensory evoked potentials (SSEPs) in predicting outcome in comatose survivors of cardiac arrest treated with therapeutic hypothermia (TH) has been questioned. We investigated whether the absence of cortical (N20) responses was a reliable predictor of a nonawakening in the setting of TH. METHODS A retrospective review was conducted in cardiac arrest survivors treated with TH admitted to a single tertiary care hospital from April, 2010 to March, 2013 who underwent SSEP testing at various time points after cardiac arrest. N20 responses were categorized as normal, present but abnormal, bilaterally absent, or inadequate for interpretation. Neurologic outcome was assessed at discharge by the Cerebral Performance Category Scale (CPC). RESULTS Ninety-three SSEP studies were performed in 73 patients. Fourteen patients had absent N20 responses; all had poor outcome (CPC 4-5). Eleven patients had absent N20 s during hypothermia, three of whom had follow-up SSEPs after rewarming and cortical responses remained absent. Fifty-seven patients had N20 peaks identified and had variable outcomes. Evaluation of 1 or more N20 peaks was limited or inadequate in 11.4% of SSEPs performed during the cooling because of artifact. CONCLUSIONS Somatosensory evoked potentials remain a reliable prognostic indicator in patients undergoing TH. The limited sample size of patients who had SSEP performed during TH and repeated after normothermia added to the effect of self-fulfilling prophecy limit the interpretation of the reliability of this testing when performed during cooling. Further prospective, multicenter, large scale studies correlating cortical responses in SSEPs during and after TH are warranted. Technical challenges are commonplace during TH and caution is advised in the interpretation of suboptimal recordings.
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Soplata AE, McCarthy MM, Sherfey J, Lee S, Purdon PL, Brown EN, Kopell N. Thalamocortical control of propofol phase-amplitude coupling. PLoS Comput Biol 2017; 13:e1005879. [PMID: 29227992 PMCID: PMC5739502 DOI: 10.1371/journal.pcbi.1005879] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 12/21/2017] [Accepted: 10/02/2017] [Indexed: 11/18/2022] Open
Abstract
The anesthetic propofol elicits many different spectral properties on the EEG, including alpha oscillations (8-12 Hz), Slow Wave Oscillations (SWO, 0.1-1.5 Hz), and dose-dependent phase-amplitude coupling (PAC) between alpha and SWO. Propofol is known to increase GABAA inhibition and decrease H-current strength, but how it generates these rhythms and their interactions is still unknown. To investigate both generation of the alpha rhythm and its PAC to SWO, we simulate a Hodgkin-Huxley network model of a hyperpolarized thalamus and corticothalamic inputs. We find, for the first time, that the model thalamic network is capable of independently generating the sustained alpha seen in propofol, which may then be relayed to cortex and expressed on the EEG. This dose-dependent sustained alpha critically relies on propofol GABAA potentiation to alter the intrinsic spindling mechanisms of the thalamus. Furthermore, the H-current conductance and background excitation of these thalamic cells must be within specific ranges to exhibit any intrinsic oscillations, including sustained alpha. We also find that, under corticothalamic SWO UP and DOWN states, thalamocortical output can exhibit maximum alpha power at either the peak or trough of this SWO; this implies the thalamus may be the source of propofol-induced PAC. Hyperpolarization level is the main determinant of whether the thalamus exhibits trough-max PAC, which is associated with lower propofol dose, or peak-max PAC, associated with higher dose. These findings suggest: the thalamus generates a novel rhythm under GABAA potentiation such as under propofol, its hyperpolarization may determine whether a patient experiences trough-max or peak-max PAC, and the thalamus is a critical component of propofol-induced cortical spectral phenomena. Changes to the thalamus may be a critical part of how propofol accomplishes its effects, including unconsciousness.
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Affiliation(s)
- Austin E. Soplata
- Graduate Program for Neuroscience, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
| | - Michelle M. McCarthy
- Department of Mathematics & Statistics, Boston University, Boston, Massachusetts, United States of America
| | - Jason Sherfey
- Department of Psychological and Brain Sciences, Boston University, Boston, Massachusetts, United States of America
| | - Shane Lee
- Department of Neuroscience, Brown University, Providence, Rhode Island, United States of America
| | - Patrick L. Purdon
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Emery N. Brown
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Nancy Kopell
- Department of Mathematics & Statistics, Boston University, Boston, Massachusetts, United States of America
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Fu B, Liu C, Zhang Y, Fu X, Zhang L, Yu T. Ketamine attenuates the glutamatergic neurotransmission in the ventral posteromedial nucleus slices of rats. BMC Anesthesiol 2017; 17:111. [PMID: 28835217 PMCID: PMC5569565 DOI: 10.1186/s12871-017-0404-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 08/16/2017] [Indexed: 01/15/2023] Open
Abstract
Background Ketamine is a frequently used intravenous anesthetic, which can reversibly induce loss of consciousness (LOC). Previous studies have demonstrated that thalamocortical system is critical for information transmission and integration in the brain. The ventral posteromedial nucleus (VPM) is a critical component of thalamocortical system. Glutamate is an important excitatory neurotransmitter in the brain and may be involved in ketamine-induced LOC. Methods The study used whole-cell patch-clamp to observe the effect of ketamine (30 μM–1000 μM) on glutamatergic neurotransmission in VPM slices. Results Ketamine significantly decreased the amplitude of glutamatergic spontaneous excitatory postsynaptic currents (sEPSCs), but only higher concentration of ketamine (300 μM and 1000 μM) suppressed the frequency of sEPSCs. Ketamine (100 μM–1000 μM) also decreased the amplitude of glutamatergic miniature excitatory postsynaptic currents (mEPSCs), without altering the frequency. Conclusions In VPM neurons, ketamine attenuates the glutamatergic neurotransmission mainly through postsynaptic mechanism and action potential may be involved in the process. Electronic supplementary material The online version of this article (doi:10.1186/s12871-017-0404-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bao Fu
- Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Chengxi Liu
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, Zunyi, Guizhou, 201, China
| | - Yajun Zhang
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, Zunyi, Guizhou, 201, China
| | - Xiaoyun Fu
- Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Lin Zhang
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, Zunyi, Guizhou, 201, China
| | - Tian Yu
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian Road, Zunyi, Guizhou, 201, China.
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Wang X, Gkogkidis CA, Iljina O, Fiederer LDJ, Henle C, Mader I, Kaminsky J, Stieglitz T, Gierthmuehlen M, Ball T. Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries. J Neural Eng 2017; 14:056004. [DOI: 10.1088/1741-2552/aa785e] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Wright NC, Wessel R. Network activity influences the subthreshold and spiking visual responses of pyramidal neurons in the three-layer turtle cortex. J Neurophysiol 2017; 118:2142-2155. [PMID: 28747466 DOI: 10.1152/jn.00340.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 07/17/2017] [Accepted: 07/20/2017] [Indexed: 11/22/2022] Open
Abstract
A primary goal of systems neuroscience is to understand cortical function, typically by studying spontaneous and stimulus-modulated cortical activity. Mounting evidence suggests a strong and complex relationship exists between the ongoing and stimulus-modulated cortical state. To date, most work in this area has been based on spiking in populations of neurons. While advantageous in many respects, this approach is limited in scope: it records the activity of a minority of neurons and gives no direct indication of the underlying subthreshold dynamics. Membrane potential recordings can fill these gaps in our understanding, but stable recordings are difficult to obtain in vivo. Here, we recorded subthreshold cortical visual responses in the ex vivo turtle eye-attached whole brain preparation, which is ideally suited for such a study. We found that, in the absence of visual stimulation, the network was "synchronous"; neurons displayed network-mediated transitions between hyperpolarized (Down) and depolarized (Up) membrane potential states. The prevalence of these slow-wave transitions varied across turtles and recording sessions. Visual stimulation evoked similar Up states, which were on average larger and less reliable when the ongoing state was more synchronous. Responses were muted when immediately preceded by large, spontaneous Up states. Evoked spiking was sparse, highly variable across trials, and mediated by concerted synaptic inputs that were, in general, only very weakly correlated with inputs to nearby neurons. Together, these results highlight the multiplexed influence of the cortical network on the spontaneous and sensory-evoked activity of individual cortical neurons.NEW & NOTEWORTHY Most studies of cortical activity focus on spikes. Subthreshold membrane potential recordings can provide complementary insight, but stable recordings are difficult to obtain in vivo. Here, we recorded the membrane potentials of cortical neurons during ongoing and visually evoked activity. We observed a strong relationship between network and single-neuron evoked activity spanning multiple temporal scales. The membrane potential perspective of cortical dynamics thus highlights the influence of intrinsic network properties on visual processing.
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Affiliation(s)
- Nathaniel C Wright
- Department of Physics, Washington University in St. Louis, St. Louis, Missouri
| | - Ralf Wessel
- Department of Physics, Washington University in St. Louis, St. Louis, Missouri
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Fu B, Wang Y, Yang H, Yu T. Effects of Etomidate on GABAergic and Glutamatergic Transmission in Rat Thalamocortical Slices. Neurochem Res 2016; 41:3181-3191. [PMID: 27561291 DOI: 10.1007/s11064-016-2042-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 08/10/2016] [Accepted: 08/22/2016] [Indexed: 12/14/2022]
Abstract
Although accumulative evidence indicates that the thalamocortical system is an important target for general anesthetics, the underlying mechanisms of anesthetic action on thalamocortical neurotransmission are not fully understood. The aim of the study is to explore the action of etomidate on glutamatergic and GABAergic transmission in rat thalamocortical slices by using whole cell patch-clamp recording. We found that etomidate mainly prolonged the decay time of spontaneous GABAergic inhibitory postsynaptic currents (sIPSCs), without changing the frequency. Furthermore, etomidate not only prolonged the decay time of miniature inhibitory postsynaptic currents (mIPSCs) but also increased the amplitude. On the other hand, etomidate significantly decreased the frequency of spontaneous glutamatergic excitatory postsynaptic currents (sEPSCs), without altering the amplitude or decay time in the absence of bicuculline. When GABAA receptors were blocked using bicuculline, the effects of etomidate on sEPSCs were mostly eliminated. These results suggest that etomidate enhances GABAergic transmission mainly through postsynaptic mechanism in thalamocortical neuronal network. Etomidate attenuates glutamatergic transmission predominantly through presynaptic action and requires presynaptic GABAA receptors involvement.
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Affiliation(s)
- Bao Fu
- Department of Critical Care Medicine, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Yuan Wang
- Department of Anesthesiology, Affiliated Hospital of Zunyi Medical College, Zunyi, Guizhou, China
| | - Hao Yang
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian road 149, Zunyi, 563000, Guizhou, China
| | - Tian Yu
- Guizhou Key Laboratory of Anesthesia and Organ Protection, Zunyi Medical College, Dalian road 149, Zunyi, 563000, Guizhou, China.
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Effects of Ketamine on Neuronal Spontaneous Excitatory Postsynaptic Currents and Miniature Excitatory Postsynaptic Currents in the Somatosensory Cortex of Rats. IRANIAN JOURNAL OF MEDICAL SCIENCES 2016; 41:275-82. [PMID: 27365548 PMCID: PMC4912645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Ketamine is a commonly used intravenous anesthetic which produces dissociation anesthesia, analgesia, and amnesia. The mechanism of ketamine-induced synaptic inhibition in high-level cortical areas is still unknown. We aimed to elucidate the effects of different concentrations of ketamine on the glutamatergic synaptic transmission of the neurons in the primary somatosensory cortex by using the whole-cell patch-clamp method. METHODS Sprague-Dawley rats (11-19 postnatal days, n=36) were used to obtain brain slices (300 μM). Spontaneous excitatory postsynaptic currents (data from 40 neurons) were recorded at a command potential of -70 mV in the presence of bicuculline (a competitive antagonist of GABAA receptors, 30 μM) and strychnine (glycine receptor antagonist, 30 μM). Miniature excitatory postsynaptic currents (data from 40 neurons) were also recorded when 1 μM of tetrodotoxin was added into the artificial cerebrospinal fluid. We used GraphPad Prism5for statistical analysis. Significant differences in the mean amplitude and frequency were tested using the Student paired 2-tailed t test. Values of P<0.05 were considered significant. RESULTS Different concentrations of ketamine inhibited the frequency and amplitude of the spontaneous excitatory postsynaptic currents as well as the amplitude of the miniature excitatory postsynaptic currents in a concentration-dependent manner, but they exerted no significant effect on the frequency of the miniature excitatory postsynaptic currents. CONCLUSION Ketamine inhibited the excitatory synaptic transmission of the neurons in the primary somatosensory cortex. The inhibition may have been mediated by a reduction in the sensitivity of the postsynaptic glutamatergic receptors.
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