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Kanade PP, Oyunbaatar NE, Kim J, Lee BK, Kim ES, Lee DW. Cardiotoxicity Assessment through a Polymer-Based Cantilever Platform: An Integrated Electro-Mechanical Screening Approach. Small 2024:e2311274. [PMID: 38511575 DOI: 10.1002/smll.202311274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 03/08/2024] [Indexed: 03/22/2024]
Abstract
Preclinical drug screening for cardiac toxicity has traditionally relied on observing changes in cardiomyocytes' electrical activity, primarily through invasive patch clamp techniques or non-invasive microelectrode arrays (MEA). However, relying solely on field potential duration (FPD) measurements for electrophysiological assessment can miss the full spectrum of drug-induced toxicity, as different drugs affect cardiomyocytes through various mechanisms. A more comprehensive approach, combining field potential and contractility measurements, is essential for accurate toxicity profiling, particularly for drugs targeting contractile proteins without affecting electrophysiology. However, previously proposed platform has significant limitations in terms of simultaneous measurement. The novel platform addresses these issues, offering enhanced, non-invasive evaluation of drug-induced cardiotoxicity. It features eight cantilevers with patterned strain sensors and MEA, enabling real-time monitoring of both cardiomyocyte contraction force and field potential. This system can detect minimum cardiac contraction force of ≈2 µN and field potential signals with 50 µm MEA diameter, using the same cardiomyocytes in measurements of two parameters. Testing with six drugs of varied mechanisms of action, the platform successfully identifies these mechanisms and accurately assesses toxicity profiles, including drugs not inhibiting potassium channels. This innovative approach presents a comprehensive, non-invasive method for cardiac function assessment, poised to revolutionize preclinical cardiotoxicity screening.
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Affiliation(s)
- Pooja P Kanade
- School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea
- Advanced Medical Device Research Center for Cardiovascular Disease, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Nomin-Erdene Oyunbaatar
- School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea
- Advanced Medical Device Research Center for Cardiovascular Disease, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Jongyun Kim
- School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea
- Advanced Medical Device Research Center for Cardiovascular Disease, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Bong-Kee Lee
- School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea
| | - Eung-Sam Kim
- Department of Biological Sciences, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Dong-Weon Lee
- School of Mechanical Engineering, Chonnam National University, Gwangju, 61186, South Korea
- Advanced Medical Device Research Center for Cardiovascular Disease, Chonnam National University, Gwangju, 61186, Republic of Korea
- Center for Next-Generation Sensor Research and Development, Chonnam National University, Gwangju, 61186, Republic of Korea
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Ernault AC, Al-Shama RFM, Li J, Devalla HD, de Groot JR, Coronel R, Vigmond E, Boukens BJ. Interpretation of field and LEAP potentials recorded from cardiomyocyte monolayers. Am J Physiol Heart Circ Physiol 2024; 326:H800-H811. [PMID: 38180452 DOI: 10.1152/ajpheart.00463.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 12/04/2023] [Accepted: 01/02/2024] [Indexed: 01/06/2024]
Abstract
Multielectrode arrays (MEAs) are the method of choice for electrophysiological characterization of cardiomyocyte monolayers. The field potentials recorded using an MEA are like extracellular electrograms recorded from the myocardium using conventional electrodes. Nevertheless, different criteria are used to interpret field potentials and extracellular electrograms, which hamper correct interpretation and translation to the patient. To validate the criteria for interpretation of field potentials, we used neonatal rat cardiomyocytes to generate monolayers. We recorded field potentials using an MEA and simultaneously recorded action potentials using sharp microelectrodes. In parallel, we recreated our experimental setting in silico and performed simulations. We show that the amplitude of the local RS complex of a field potential correlated with conduction velocity in silico but not in vitro. The peak time of the T wave in field potentials exhibited a strong correlation with APD90 while the steepest upslope correlated well with APD50. However, this relationship only holds when the T wave displayed a biphasic pattern. Next, we simulated local extracellular action potentials (LEAPs). The shape of the LEAP differed markedly from the shape of the local action potential, but the final duration of the LEAP coincided with APD90. Criteria for interpretation of extracellular electrograms should be applied to field potentials. This will provide a strong basis for the analysis of heterogeneity in conduction velocity and repolarization in cultured monolayers of cardiomyocytes. Finally, a LEAP is not a recording of the local action potential but is generated by intracellular current provided by neighboring cardiomyocytes and is superior to field potential duration in estimating APD90.NEW & NOTEWORTHY We present a physiological basis for the interpretation of multielectrode array-derived, extracellular, electrical signals.
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Affiliation(s)
- Auriane C Ernault
- Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Rushd F M Al-Shama
- Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Jiuru Li
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Harsha D Devalla
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Joris R de Groot
- Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Ruben Coronel
- Heart Center, Department of Clinical and Experimental Cardiology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Edward Vigmond
- IHU Liryc, Fondation Bordeaux Université, Bordeaux, France
- University of Bordeaux, Talence, France
| | - Bastiaan J Boukens
- Department of Medical Biology, Amsterdam Cardiovascular Sciences, Amsterdam University Medical Centers, Amsterdam, The Netherlands
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
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Ross AJ, Krumova I, Tunc B, Wu Q, Wu C, Camelliti P. A novel method to extend viability and functionality of living heart slices. Front Cardiovasc Med 2023; 10:1244630. [PMID: 37881724 PMCID: PMC10597746 DOI: 10.3389/fcvm.2023.1244630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 08/09/2023] [Indexed: 10/27/2023] Open
Abstract
Living heart slices have recently emerged as a powerful experimental model for fundamental cardiac research. By retaining the structure and function of the native myocardium while maintaining the simplicity of cell culture models, heart slices can be easily employed in electrophysiological, pharmacological, biochemical, and structural investigations. One single heart yields many slices (>20 slices for rodents, >100 slices for porcine or human hearts), however due to the low throughput of most assays and rapid slice degeneration within 24 h of preparation, many slices remain unused and are discarded at the end of the preparation day. Here we present a novel method to extend viability and functionality of living heart slices, enabling their use in experiments over several consecutive days following preparation. By combining hypothermic conditions with inhibition of myosin II ATPase using 2,3-butanedione monoxime (BDM), slices prepared from the left ventricle of porcine hearts remain viable and exhibit preserved contractile function and morphology for up to 6 days. Electrophysiological function was also confirmed over the 6 days by extracellular field potentials recordings. This simple method not only maximizes the use of slices prepared from one single heart, thus reducing the number of animals required, but also increases data reproducibility by allowing multiple electrophysiological, pharmacological, biochemical, and structural studies to be performed from the same heart.
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Affiliation(s)
- Abigail J. Ross
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - Iva Krumova
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - Berfin Tunc
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - Qin Wu
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
- School of Medicine, Jiangsu Vocational College of Medicine, Yancheng, China
| | - Changhao Wu
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - Patrizia Camelliti
- School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
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Bousseyrol E, Didienne S, Takillah S, Prevost-Solié C, Come M, Ahmed Yahia T, Mondoloni S, Vicq E, Tricoire L, Mourot A, Naudé J, Faure P. Dopaminergic and prefrontal dynamics co-determine mouse decisions in a spatial gambling task. Cell Rep 2023; 42:112523. [PMID: 37200189 DOI: 10.1016/j.celrep.2023.112523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/28/2023] [Accepted: 05/02/2023] [Indexed: 05/20/2023] Open
Abstract
The neural mechanisms by which animals initiate goal-directed actions, choose between options, or explore opportunities remain unknown. Here, we develop a spatial gambling task in which mice, to obtain intracranial self-stimulation rewards, self-determine the initiation, direction, vigor, and pace of their actions based on their knowledge of the outcomes. Using electrophysiological recordings, pharmacology, and optogenetics, we identify a sequence of oscillations and firings in the ventral tegmental area (VTA), orbitofrontal cortex (OFC), and prefrontal cortex (PFC) that co-encodes and co-determines self-initiation and choices. This sequence appeared with learning as an uncued realignment of spontaneous dynamics. Interactions between the structures varied with the reward context, particularly the uncertainty associated with the different options. We suggest that self-generated choices arise from a distributed circuit based on an OFC-VTA core determining whether to wait for or initiate actions, while the PFC is specifically engaged by reward uncertainty in action selection and pace.
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Affiliation(s)
- Elise Bousseyrol
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Steve Didienne
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Samir Takillah
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Clement Prevost-Solié
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Maxime Come
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Tarek Ahmed Yahia
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Sarah Mondoloni
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Eléonore Vicq
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Ludovic Tricoire
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
| | - Alexandre Mourot
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France
| | - Jérémie Naudé
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; CNRS, Université de Montpellier, INSERM - Institut de Génomique Fonctionnelle, 34094 Montpellier, France.
| | - Philippe Faure
- Sorbonne Université, INSERM, CNRS, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France; Brain Plasticity Laboratory, CNRS, ESPCI Paris, PSL Research University, 75005 Paris, France.
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5
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Voutsinas C, Frommelt LS, Volani C, Rossini A, Oberzaucher J. A Novel Algorithmic Approach to the Analysis of Multi-Electrode Array Signals of hiPSC-Derived Cardiomyocytes. Stud Health Technol Inform 2023; 301:48-53. [PMID: 37172151 DOI: 10.3233/shti230010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
In order to perform in vitro cardiotoxicity screening of pharmacological substances, multi-electrode array systems are increasingly used to measure the extracellular field potentials of cell layers of human induced pluripotent stem cell cardiomyocytes. The analysis of the field potentials is usually performed using complex analysis software provided by the hardware manufacturers. In the case of the Cardiac Analysis Tool software from Axion Biosystems, inconsistencies were found in the results, which can significantly influence the cardiotoxicity screening results. In order to obtain more reliable results, a new algorithm was developed and implemented in an easy-to-use software tool, the INCardio Data Analysis Tool, which, due to its high degree of automation, can also be used by inexperienced users. The validation reveals differences in the results of the two tools both in depolarization spike amplitudes and in the time course of the field potential durations. The manual analysis of all signals affected by deviations shows that the results of the newly developed Data Analysis Tool are correct in all cases and can therefore be classified as more accurate and reliable than the reference analysis software.
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Wang L, Nguyen T, Rosa-Garrido M, Zhou Y, Cleveland DC, Zhang J. Comparative analysis of the cardiomyocyte differentiation potential of induced pluripotent stem cells reprogrammed from human atrial or ventricular fibroblasts. Front Bioeng Biotechnol 2023; 11:1108340. [PMID: 36845191 PMCID: PMC9950567 DOI: 10.3389/fbioe.2023.1108340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
Background: We had shown that cardiomyocytes (CMs) were more efficiently differentiated from human induced pluripotent stem cells (hiPSCs) when the hiPSCs were reprogrammed from cardiac fibroblasts rather than dermal fibroblasts or blood mononuclear cells. Here, we continued to investigate the relationship between somatic-cell lineage and hiPSC-CM production by comparing the yield and functional properties of CMs differentiated from iPSCs reprogrammed from human atrial or ventricular cardiac fibroblasts (AiPSC or ViPSC, respectively). Methods: Atrial and ventricular heart tissues were obtained from the same patient, reprogrammed into AiPSCs or ViPSCs, and then differentiated into CMs (AiPSC-CMs or ViPSC-CMs, respectively) via established protocols. Results: The time-course of expression for pluripotency genes (OCT4, NANOG, and SOX2), the early mesodermal marker Brachyury, the cardiac mesodermal markers MESP1 and Gata4, and the cardiovascular progenitor-cell transcription factor NKX2.5 were broadly similar in AiPSC-CMs and ViPSC-CMs during the differentiation protocol. Flow-cytometry analyses of cardiac troponin T expression also indicated that purity of the two differentiated hiPSC-CM populations (AiPSC-CMs: 88.23% ± 4.69%, ViPSC-CMs: 90.25% ± 4.99%) was equivalent. While the field-potential durations were significantly longer in ViPSC-CMs than in AiPSC-CMs, measurements of action potential duration, beat period, spike amplitude, conduction velocity, and peak calcium-transient amplitude did not differ significantly between the two hiPSC-CM populations. Yet, our cardiac-origin iPSC-CM showed higher ADP and conduction velocity than previously reported iPSC-CM derived from non-cardiac tissues. Transcriptomic data comparing iPSC and iPSC-CMs showed similar gene expression profiles between AiPSC-CMs and ViPSC-CMs with significant differences when compared to iPSC-CM derived from other tissues. This analysis also pointed to several genes involved in electrophysiology processes responsible for the physiological differences observed between cardiac and non-cardiac-derived cardiomyocytes. Conclusion: AiPSC and ViPSC were differentiated into CMs with equal efficiency. Detected differences in electrophysiological properties, calcium handling activity, and transcription profiles between cardiac and non-cardiac derived cardiomyocytes demonstrated that 1) tissue of origin matters to generate a better-featured iPSC-CMs, 2) the sublocation within the cardiac tissue has marginal effects on the differentiation process.
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Affiliation(s)
- Lu Wang
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Thanh Nguyen
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Manuel Rosa-Garrido
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Yang Zhou
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
| | - David C. Cleveland
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, United States
- Children’s Hospital of Alabama, Birmingham, AL, United States
| | - Jianyi Zhang
- Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL, United States
- Department of Medicine, Division of Cardiovascular Disease, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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Hwang M, Lee SJ, Lim CH, Shim EB, Lee HA. The three-dimensionality of the hiPSC-CM spheroid contributes to the variability of the field potential. Front Physiol 2023; 14:1123190. [PMID: 37025386 PMCID: PMC10070703 DOI: 10.3389/fphys.2023.1123190] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 03/10/2023] [Indexed: 04/08/2023] Open
Abstract
Background: Field potential (FP) signals from human induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) spheroid which are used for drug safety tests in the preclinical stage are different from action potential (AP) signals and require working knowledge of the multi-electrode array (MEA) system. In this study, we developed in silico three-dimensional (3-D) models of hiPSC-CM spheroids for the simulation of field potential measurement. We compared our model simulation results against in vitro experimental data under the effect of drugs E-4031 and nifedipine. Methods: In silico 3-D models of hiPSC-CM spheroids were constructed in spherical and discoidal shapes. Tetrahedral meshes were generated inside the models, and the propagation of the action potential in the model was obtained by numerically solving the monodomain reaction-diffusion equation. An electrical model of electrode was constructed and FPs were calculated using the extracellular potentials from the AP propagations. The effects of drugs were simulated by matching the simulation results with in vitro experimental data. Results: The simulated FPs from the 3-D models of hiPSC-CM spheroids exhibited highly variable shapes depending on the stimulation and measurement locations. The values of the IC50 of E-4031 and nifedipine calculated by matching the simulated FP durations with in vitro experimental data were in line with the experimentally measured ones reported in the literature. Conclusion: The 3-D in silico models of hiPSC-CM spheroids generated highly variable FPs similar to those observed in in vitro experiments. The in silico model has the potential to complement the interpretation of the FP signals obtained from in vitro experiments.
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Affiliation(s)
| | - Su-Jin Lee
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon, Republic of Korea
| | | | - Eun Bo Shim
- AI Medic, Inc., Seoul, Republic of Korea
- Department of Mechanical and Biomedical Engineering, Kangwon National University, Chuncheon, Republic of Korea
- *Correspondence: Eun Bo Shim, ; Hyang-Ae Lee,
| | - Hyang-Ae Lee
- Department of Predictive Toxicology, Korea Institute of Toxicology, Daejeon, Republic of Korea
- *Correspondence: Eun Bo Shim, ; Hyang-Ae Lee,
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8
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Pan D, Li B, Wang S. Establishment and validation of a torsade de pointes prediction model based on human iPSC‑derived cardiomyocytes. Exp Ther Med 2022; 25:61. [PMID: 36588805 PMCID: PMC9780517 DOI: 10.3892/etm.2022.11760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 09/26/2022] [Indexed: 12/14/2022] Open
Abstract
Drug-induced cardiotoxicity is one of the main causes of drug failure, which leads to subsequent withdrawal from pharmaceutical development. Therefore, identifying the potential toxic candidate in the early stages of drug development is important. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are a useful tool for assessing candidate compounds for arrhythmias. However, a suitable model using hiPSC-CMs to predict the risk of torsade de pointes (TdP) has not been fully established. The present study aimed to establish a predictive TdP model based on hiPSC-CMs. In the current study, 28 compounds recommended by the Comprehensive in vitro Proarrhythmia Assay (CiPA) were used as training set and models were established in different risk groups, high- and intermediate-risk versus low-risk groups. Subsequently, six endpoints of electrophysiological responses were used as potential model predictors. Accuracy, sensitivity and area under the curve (AUC) were used as evaluation indices of the models and seven compounds with known TdP risk were used to verify model differentiation and calibration. The results showed that among the seven models, the AUC of logistic regression and AdaBoost model was higher and had little difference in both training and test sets, which indicated that the discriminative ability and model stability was good and excellent, respectively. Therefore, these two models were taken as submodels, similar weight was configured and a new TdP risk prediction model was constructed using a soft voting strategy. The classification accuracy, sensitivity and AUC of the new model were 0.93, 0.95 and 0.92 on the training set, respectively and all 1.00 on the test set, which indicated good discrimination ability on both training and test sets. The risk threshold was defined as 0.50 and the consistency between the predicted and observed results were 92.8 and 100% on the training and test sets, respectively. Overall, the present study established a risk prediction model for TdP based on hiPSC-CMs which could be an effective predictive tool for compound-induced arrhythmias.
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Affiliation(s)
- Dongsheng Pan
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, P.R. China,National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing 100176, P.R. China
| | - Bo Li
- Graduate School of Peking Union Medical College, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, P.R. China,National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing 100176, P.R. China
| | - Sanlong Wang
- National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing 100176, P.R. China,Correspondence to: Professor Sanlong Wang, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, A8 Hongda Middle Street, Beijing Economic-Technological Development Area, Beijing 100176, P.R. China
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9
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Ikeda K, Kataoka M, Tanaka NK. Nonsynaptic Transmission Mediates Light Context-Dependent Odor Responses in Drosophila melanogaster. J Neurosci 2022; 42:8621-8628. [PMID: 36180227 PMCID: PMC9671575 DOI: 10.1523/jneurosci.1106-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/21/2022] Open
Abstract
Recent connectome analyses of the entire synaptic circuit in the nervous system have provided tremendous insights into how neural processing occurs through the synaptic relay of neural information. Conversely, the extent to which ephaptic transmission which does not depend on the synapses contributes to the relay of neural information, especially beyond a distance between adjacent neurons and to neural processing remains unclear. We show that ephaptic transmission mediated by extracellular potential changes in female Drosophila melanogaster can reach >200 µm, equivalent to the depth of its brain. Furthermore, ephaptic transmission driven by retinal photoreceptor cells mediates light-evoked firing rate increases in olfactory sensory neurons. These results indicate that ephaptic transmission contributes to sensory responses that can change momentarily in a context-dependent manner.SIGNIFICANCE STATEMENT Although extracellular field potential activities are commonly observed in many nervous systems, this activity has been generally considered as a side effect of synchronized spiking of neurons. This study, however, shows that field potential changes in retinae evoked by a sensory stimulus can control the excitability of distant neurons in vivo and mediates multimodal sensory integration in Drosophila melanogaster As such ephaptic transmission is more effective at a short distance, the ephaptic transmission from the retinae may contribute significantly to firing rate changes in downstream neurons of the photoreceptor cells in the optic lobe.
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Affiliation(s)
- Kazuaki Ikeda
- Division of Biology, Department of Biological Sciences, School of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Graduate School of Life Sciences, Hokkaido University, Sapporo, 060-0810, Japan
| | - Masaki Kataoka
- Division of Biology, Department of Biological Sciences, School of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Graduate School of Life Sciences, Hokkaido University, Sapporo, 060-0810, Japan
| | - Nobuaki K Tanaka
- Division of Biology, Department of Biological Sciences, School of Science, Hokkaido University, Sapporo, 060-0810, Japan
- Graduate School of Life Sciences, Hokkaido University, Sapporo, 060-0810, Japan
- Faculty of Science, Hokkaido University, Sapporo, 060-0810, Japan
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10
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Postnikova TY, Diespirov GP, Amakhin DV, Vylekzhanina EN, Soboleva EB, Zaitsev AV. Impairments of Long-Term Synaptic Plasticity in the Hippocampus of Young Rats during the Latent Phase of the Lithium-Pilocarpine Model of Temporal Lobe Epilepsy. Int J Mol Sci 2021; 22:ijms222413355. [PMID: 34948152 PMCID: PMC8705146 DOI: 10.3390/ijms222413355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/06/2021] [Accepted: 12/10/2021] [Indexed: 12/14/2022] Open
Abstract
Status epilepticus (SE) causes persistent abnormalities in the functioning of neuronal networks, often resulting in worsening epileptic seizures. Many details of cellular and molecular mechanisms of seizure-induced changes are still unknown. The lithium–pilocarpine model of epilepsy in rats reproduces many features of human temporal lobe epilepsy. In this work, using the lithium–pilocarpine model in three-week-old rats, we examined the morphological and electrophysiological changes in the hippocampus within a week following pilocarpine-induced seizures. We found that almost a third of the neurons in the hippocampus and dentate gyrus died on the first day, but this was not accompanied by impaired synaptic plasticity at that time. A diminished long-term potentiation (LTP) was observed following three days, and the negative effect of SE on plasticity increased one week later, being accompanied by astrogliosis. The attenuation of LTP was caused by the weakening of N-methyl-D-aspartate receptor (NMDAR)-dependent signaling. NMDAR-current was more than two-fold weaker during high-frequency stimulation in the post-SE rats than in the control group. Application of glial transmitter D-serine, a coagonist of NMDARs, allows the enhancement of the NMDAR-dependent current and the restoration of LTP. These results suggest that the disorder of neuron–astrocyte interactions plays a critical role in the impairment of synaptic plasticity.
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Abstract
Pannexin1 (Panx1) is an ATP release channel expressed in neurons and astrocytes that plays important roles in CNS physiology and pathology. Evidence for the involvement of Panx1 in seizures includes the reduction of epileptiform activity and ictal discharges following Panx1 channel blockade or deletion. However, very little is known about the relative contribution of astrocyte and neuronal Panx1 channels to hyperexcitability. To this end, mice with global and cell type specific deletion of Panx1 were used in one in vivo and two in vitro seizure models. In the low-Mg2+ in vitro model, global deletion but not cell-type specific deletion of Panx1 reduced the frequency of epileptiform discharges. This reduced frequency of discharges did not impact the overall power spectra obtained from local field potentials. In the in vitro KA model, in contrast, global or cell type specific deletion of Panx1 did not affect the frequency of discharges, but reduced the overall power spectra. EEG recordings following KA-injection in vivo revealed that although global deletion of Panx1 did not affect the onset of status epilepticus (SE), SE onset was delayed in mice lacking neuronal Panx1 and accelerated in mice lacking astrocyte Panx1. EEG power spectral analysis disclosed a Panx1-dependent cortical region effect; while in the occipital region, overall spectral power was reduced in all three Panx1 genotypes; in the frontal cortex, the overall power was not affected by deletion of Panx1. Together, our results show that the contribution of Panx1 to ictal activity is model, cell-type and brain region dependent.
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Affiliation(s)
- Price Obot
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States
| | - Libor Velíšek
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States.,Department of Neurology, New York Medical College, Valhalla, New York, United States.,Department of Pediatrics, New York Medical College, Valhalla, New York, United States
| | - Jana Velíšková
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States.,Department of Neurology, New York Medical College, Valhalla, New York, United States.,Department of Obstetrics & Gynecology, New York Medical College, Valhalla, New York, United States
| | - Eliana Scemes
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States
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12
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Visone R, Ugolini GS, Cruz-Moreira D, Marzorati S, Piazza S, Pesenti E, Redaelli A, Moretti M, Occhetta P, Rasponi M. Micro-electrode channel guide (µECG) technology: an online method for continuous electrical recording in a human beating heart-on-chip. Biofabrication 2021; 13. [PMID: 33561845 DOI: 10.1088/1758-5090/abe4c4] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 02/09/2021] [Indexed: 12/19/2022]
Abstract
Cardiac toxicity still represents a common adverse outcome causing drug attrition and post-marketing withdrawal. The development of relevant in vitro models resembling the human heart recently opened the path towards a more accurate detection of drug-induced human cardiac toxicity early in the drug development process. Organs-on-chip (OoC) have been proposed as promising tools to recapitulate in vitro the key aspects of the in vivo cardiac physiology and to provide a means to directly analyze functional readouts. In this scenario, a new device capable of continuous monitoring of electrophysiological signals from functional in vitro human hearts-on-chip is here presented. The development of cardiac microtissues was achieved through a recently published method to control the mechanical environment, while the introduction of a technology consisting in micro-electrode coaxial guides (µECG) allowed to conduct direct and non-destructive electrophysiology studies. The generated human cardiac microtissues exhibited synchronous spontaneous beating, as demonstrated by multi-point and continuous acquisition of cardiac field potential, and expression of relevant genes encoding for cardiac ion-channels. A proof-of-concept pharmacological validation on 3 drugs proved the proposed model to potentially be a powerful tool to evaluate functional cardiac toxicity.
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Affiliation(s)
- Roberta Visone
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
| | - Giovanni Stefano Ugolini
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
| | - Daniela Cruz-Moreira
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
| | - Simona Marzorati
- Translational Medicine, Accelera Srl, via Pasteur, Nerviano, Nerviano, MI, 20100, ITALY
| | - Stefano Piazza
- BiomimX Srl, Via Giovanni Durando 38/A, Milan, 20158, ITALY
| | | | - Alberto Redaelli
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
| | - Matteo Moretti
- Cell and Tissue Engineering Lab, IRCCS Galeazzi Orthopaedic Institute, via R Galeazzi 4, Milan, 20161, ITALY
| | - Paola Occhetta
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
| | - Marco Rasponi
- Politecnico di Milano Dipartimento di Elettronica Informazione e Bioingegneria, Via Ponzio 34/5, Milano, Lombardia, 20133, ITALY
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13
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Torres D, Makarova J, Ortuño T, Benito N, Makarov VA, Herreras O. Local and Volume-Conducted Contributions to Cortical Field Potentials. Cereb Cortex 2020; 29:5234-5254. [PMID: 30941394 DOI: 10.1093/cercor/bhz061] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/14/2019] [Accepted: 02/28/2019] [Indexed: 12/20/2022] Open
Abstract
Brain field potentials (FPs) can reach far from their sources, making difficult to know which waves come from where. We show that modern algorithms efficiently segregate the local and remote contributions to cortical FPs by recovering the generator-specific spatial voltage profiles. We investigated experimentally and numerically the local and remote origin of FPs in different cortical areas in anesthetized rats. All cortices examined show significant state, layer, and region dependent contribution of remote activity, while the voltage profiles help identify their subcortical or remote cortical origin. Co-activation of different cortical modules can be discriminated by the distinctive spatial features of the corresponding profiles. All frequency bands contain remote activity, thus influencing the FP time course, in cases drastically. The reach of different FP patterns is boosted by spatial coherence and curved geometry of the sources. For instance, slow cortical oscillations reached the entire brain, while hippocampal theta reached only some portions of the cortex. In anterior cortices, most alpha oscillations have a remote origin, while in the visual cortex the remote theta and gamma even surpass the local contribution. The quantitative approach to local and distant FP contributions helps to refine functional connectivity among cortical regions, and their relation to behavior.
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Affiliation(s)
- Daniel Torres
- Department of Translational Neuroscience, Cajal Institute - CSIC, Av. Dr. Arce 37, Madrid, Spain
| | - Julia Makarova
- Department of Translational Neuroscience, Cajal Institute - CSIC, Av. Dr. Arce 37, Madrid, Spain
| | - Tania Ortuño
- Department of Translational Neuroscience, Cajal Institute - CSIC, Av. Dr. Arce 37, Madrid, Spain
| | - Nuria Benito
- Department of Translational Neuroscience, Cajal Institute - CSIC, Av. Dr. Arce 37, Madrid, Spain
| | - Valeri A Makarov
- Instituto de Matemática Interdisciplinar, Faculty of Mathematics, Universidad, Complutense de Madrid, Madrid, Spain.,N.I. Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Oscar Herreras
- Department of Translational Neuroscience, Cajal Institute - CSIC, Av. Dr. Arce 37, Madrid, Spain
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14
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Izumi-Nakaseko H, Chiba K, Hagiwara-Nagasawa M, Satsuka A, Goto A, Nunoi Y, Kambayashi R, Matsumoto A, Takei Y, Kanda Y, Naito AT, Sugiyama A. Optimizing the Direction and Order of the Motion Unveiled the Ability of Conventional Monolayers of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes to Show Frequency-Dependent Enhancement of Contraction and Relaxation Motion. Front Cell Dev Biol 2020; 8:542562. [PMID: 33015053 PMCID: PMC7511828 DOI: 10.3389/fcell.2020.542562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 08/19/2020] [Indexed: 11/13/2022] Open
Abstract
Contractility of the human heart increases as its beating rate is elevated, so-called positive force-frequency relationship; however, human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been reported to exert a negative force-frequency relationship. We tested the hypothesis that the regulation of motion directions by electrical pacing and/or oxygen supply may improve the electro-mechanical properties of hiPSC-CMs monolayers. To better evaluate the spatial and temporal relationship between electrical excitation and contractile motion, we simultaneously observed the field potential and motion vector of hiPSC-CMs sheets. Under spontaneous contraction, although an electrical excitation originating from a region propagated unidirectionally over the cell sheet, contraction wave started from multiple sites, and relaxation wave was initiated from a geometric center of hiPSC-CMs sheet. During electrical pacing, contraction and relaxation waves were propagated from the stimulated site. Interestingly, the maximum contraction speed was more increased when the hiPSC-CMs sheet was stimulated at an area relaxation initiated under spontaneous condition. Furthermore, motion vector analysis demonstrated that "positive contraction velocity-frequency relationship" in contraction and "frequency-dependent enhancement of relaxation" were produced in the cell sheet by optimizing the direction and order of the contractile motion with pacing at the relaxation-initiating area. A close analysis of motion vectors along with field potential recording demonstrated that relaxation process consists of fast and slow phases, and suggest that intracellular Ca2+ dynamics may be closely related to functions of Ca2+-ATPase pump and Na+-Ca2+ exchangers. Namely, the slow relaxation phase occurred after the second peak of field potential, suggesting that the slow phase may be associated with extrusion of Ca2+ by Na+-Ca2+ exchangers during repolarization. Increase of oxygen concentration from 20 to 95% as well as β-adrenergic stimulation with isoproterenol accelerated the fast relaxation, suggesting that it could depend on Ca2+ uptake via Ca2+-ATPase during the depolarization phase. The ratio of maximum contraction speed to field potential duration was increased by the β-adrenergic stimulation, indicating the elevated contraction efficiency per Ca2+-influx. Thus, these findings revealed potential ability of conventional monolayers of hiPSC-CMs, which will help apply them to translational study filling the gap between physiological as well as pharmacological studies and clinical practice.
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Affiliation(s)
| | - Koki Chiba
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | | | - Ayano Satsuka
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, Japan
| | - Ai Goto
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Yoshio Nunoi
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Ryuichi Kambayashi
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Akio Matsumoto
- Department of Aging Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Yoshinori Takei
- Department of Translational Research & Cellular Therapeutics, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Yasunari Kanda
- Division of Pharmacology, National Institute of Health Sciences, Kanagawa, Japan
| | - Atsuhiko T Naito
- Department of Physiology, Division of Cell Physiology, Graduate School of Medicine, Toho University, Tokyo, Japan
| | - Atsushi Sugiyama
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan.,Department of Aging Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan.,Department of Translational Research & Cellular Therapeutics, Faculty of Medicine, Toho University, Tokyo, Japan
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15
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Kang S, Hayashi Y, Bruyns-Haylett M, Delivopoulos E, Zheng Y. Model-Predicted Balance Between Neural Excitation and Inhibition Was Maintained Despite of Age-Related Decline in Sensory Evoked Local Field Potential in Rat Barrel Cortex. Front Syst Neurosci 2020; 14:24. [PMID: 32528256 PMCID: PMC7247833 DOI: 10.3389/fnsys.2020.00024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 04/08/2020] [Indexed: 11/25/2022] Open
Abstract
The balance between neural excitation and inhibition has been shown to be crucial for normal brain function. However, it is unclear whether this balance is maintained through healthy aging. This study investigated the effect of aging on the temporal dynamics of the somatosensory evoked local field potential (LFP) in rats and tested the hypothesis that excitatory and inhibitory post-synaptic activities remain balanced during the aging process. The LFP signal was obtained from the barrel cortex of three different age groups of anesthetized rats (pre-adolescence: 4–6 weeks, young adult: 2–3 months, middle-aged adult: 10–20 months) under whisker pad stimulation. To confirm our previous finding that the initial segment of the evoked LFP was solely associated with excitatory post-synaptic activity, we micro-injected gabazine into the barrel cortex to block inhibition while LFP was collected continuously under the same stimulus condition. As expected, the initial slope of the evoked LFP in the granular layer was unaffected by gabazine injection. We subsequently estimated the excitatory and inhibitory post-synaptic activities through a balanced model of the LFP with delayed inhibition as an explicit constraint, and calculated the amplitude ratio of inhibition to excitation. We found an age-dependent slowing of the temporal dynamics in the somatosensory-evoked post-synaptic activity, as well as a significant age-related decrease in the amplitude of the excitatory component and a decreasing trend in the amplitude of the inhibitory component. Furthermore, the delay of inhibition with respect to excitation was significantly increased with age, but the amplitude ratio was maintained. Our findings suggest that aging reduces the amplitude of neural responses, but the balance between sensory evoked excitatory and inhibitory post-synaptic activities is maintained to support normal brain function during healthy aging. Further whole cell patch clamp experiments will be needed to confirm or refute these findings by measuring sensory evoked synaptic excitatory and inhibitory activities in vivo during the normal aging process.
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Affiliation(s)
- Sungmin Kang
- Biomedical Engineering, School of Biological Sciences, University of Reading, Reading, United Kingdom.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| | - Yurie Hayashi
- Biomedical Engineering, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Michael Bruyns-Haylett
- Department of Bioengineering, Imperial College, South Kensington Campus, London, United Kingdom
| | - Evangelos Delivopoulos
- Biomedical Engineering, School of Biological Sciences, University of Reading, Reading, United Kingdom.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
| | - Ying Zheng
- Biomedical Engineering, School of Biological Sciences, University of Reading, Reading, United Kingdom.,Centre for Integrative Neuroscience and Neurodynamics (CINN), University of Reading, Reading, United Kingdom
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16
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He M, Jiang X, Zou Z, Qin X, Zhang S, Guo Y, Wang X, Tian X, Chen C. Exposure to carbon black nanoparticles increases seizure susceptibility in male mice. Nanotoxicology 2020; 14:595-611. [PMID: 32091294 DOI: 10.1080/17435390.2020.1728412] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m3) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure.
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Affiliation(s)
- Miaoqing He
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China.,Chinese Institute for Brain Research, Peking University, Beijing, China
| | - Xuejun Jiang
- Center of Experimental Teaching for Public Health, Experimental Teaching and Management Center, Chongqing Medical University, Chongqing, China
| | - Zhen Zou
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China.,Dongsheng Lung-Brain Diseases Joint Lab, Chongqing Medical University, Chongqing, China
| | - Xia Qin
- Department of Pharmacy, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Shanshan Zhang
- Department of Occupational and Environmental Health, School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Yi Guo
- Department of Neurology, First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xuefeng Wang
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, China.,Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, China.,Department of Neurology, First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Xin Tian
- Department of Neurology, First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Neurology, Chongqing, China
| | - Chengzhi Chen
- Dongsheng Lung-Brain Diseases Joint Lab, Chongqing Medical University, Chongqing, China.,Department of Occupational and Environmental Health, School of Public Health and Management, Chongqing Medical University, Chongqing, China
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17
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Bertone-Cueto NI, Makarova J, Mosqueira A, García-Violini D, Sánchez-Peña R, Herreras O, Belluscio M, Piriz J. Volume-Conducted Origin of the Field Potential at the Lateral Habenula. Front Syst Neurosci 2020; 13:78. [PMID: 31998083 PMCID: PMC6961596 DOI: 10.3389/fnsys.2019.00078] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/02/2019] [Indexed: 01/30/2023] Open
Abstract
Field potentials (FPs) are easily reached signals that provide information about the brain's processing. However, FP should be interpreted cautiously since their biophysical bases are complex. The lateral habenula (LHb) is a brain structure involved in the encoding of aversive motivational values. Previous work indicates that the activity of the LHb is relevant for hippocampal-dependent learning. Moreover, it has been proposed that the interaction of the LHb with the hippocampal network is evidenced by the synchronization of LHb and hippocampal FPs during theta rhythm. However, the origin of the habenular FP has not been analyzed. Hence, its validity as a measurement of LHb activity has not been proven. In this work, we used electrophysiological recordings in anesthetized rats and feed-forward modeling to investigate biophysical basis of the FP recorded in the LHb. Our results indicate that the FP in the LHb during theta rhythm is a volume-conducted signal from the hippocampus. This result highlight that FPs must be thoroughly analyzed before its biological interpretation and argues against the use of the habenular FP signal as a readout of the activity of the LHb.
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Affiliation(s)
- Nicolas Iván Bertone-Cueto
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica “Houssay” (IFIBIO “Houssay”), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | | | - Alejo Mosqueira
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica “Houssay” (IFIBIO “Houssay”), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | | | | | | | - Mariano Belluscio
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica “Houssay” (IFIBIO “Houssay”), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Joaquin Piriz
- Grupo de Neurociencia de Sistemas, Instituto de Fisiología y Biofísica “Houssay” (IFIBIO “Houssay”), Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
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18
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Kussauer S, David R, Lemcke H. hiPSCs Derived Cardiac Cells for Drug and Toxicity Screening and Disease Modeling: What Micro- Electrode-Array Analyses Can Tell Us. Cells 2019; 8:cells8111331. [PMID: 31661896 PMCID: PMC6912416 DOI: 10.3390/cells8111331] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/19/2022] Open
Abstract
Human induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CM) have been intensively used in drug development and disease modeling. Since iPSC-cardiomyocyte (CM) was first generated, their characterization has become a major focus of research. Multi-/micro-electrode array (MEA) systems provide a non-invasive user-friendly platform for detailed electrophysiological analysis of iPSC cardiomyocytes including drug testing to identify potential targets and the assessment of proarrhythmic risk. Here, we provide a systematical overview about the physiological and technical background of micro-electrode array measurements of iPSC-CM. We introduce the similarities and differences between action- and field potential and the advantages and drawbacks of MEA technology. In addition, we present current studies focusing on proarrhythmic side effects of novel and established compounds combining MEA systems and iPSC-CM. MEA technology will help to open a new gateway for novel therapies in cardiovascular diseases while reducing animal experiments at the same time.
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Affiliation(s)
- Sophie Kussauer
- Department Cardiac Surgery, Medical Center, University of Rostock, 18057 Rostock, Germany.
| | - Robert David
- Department Cardiac Surgery, Medical Center, University of Rostock, 18057 Rostock, Germany.
| | - Heiko Lemcke
- Department Cardiac Surgery, Medical Center, University of Rostock, 18057 Rostock, Germany.
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19
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Ortuño T, López-Madrona VJ, Makarova J, Tapia-Gonzalez S, Muñoz A, DeFelipe J, Herreras O. Slow-Wave Activity in the S1HL Cortex Is Contributed by Different Layer-Specific Field Potential Sources during Development. J Neurosci 2019; 39:8900-15. [PMID: 31548234 DOI: 10.1523/JNEUROSCI.1212-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 08/06/2019] [Accepted: 08/27/2019] [Indexed: 01/12/2023] Open
Abstract
Spontaneous correlated activity in cortical columns is critical for postnatal circuit refinement. We used spatial discrimination techniques to explore the late maturation of synaptic pathways through the laminar distribution of the field potential (FP) generators underlying spontaneous and evoked activities of the S1HL cortex in juvenile (P14-P16) and adult anesthetized rats. Juveniles exhibit an intermittent FP pattern resembling Up/Down states in adults, but with much reduced power and different laminar distribution. Whereas FPs in active periods are dominated by a layer VI generator in juveniles, in adults a developing multipart generator takes over, displaying current sinks in middle layers (III-V). The blockade of excitatory transmission in upper and middle layers of adults recovered the juvenile-like FP profiles. In addition to the layer VI generator, a gamma-specific generator in supragranular layers was the same in both age groups. While searching for dynamical coupling among generators in juveniles we found significant cross-correlation in ∼one-half of the tested pairs, whereas excessive coherence hindered their efficient separation in adults. Also, potentials evoked by tactile and electrical stimuli showed different short-latency dipoles between the two age groups, and the juveniles lacked the characteristic long latency UP state currents in middle layers. In addition, the mean firing rate of neurons was lower in juveniles. Thus, cortical FPs originate from different intra-columnar segments as they become active postnatally. We suggest that although some cortical segments are active early postnatally, a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.SIGNIFICANCE STATEMENT Early postnatal activity in the rodent cortex is mostly endogenous, whereas it becomes driven by peripheral input at later stages. The precise schedule for the maturation of synaptic pathways is largely unknown. We explored this in the somatosensory hindlimb cortex at an age when animals begin to use their limbs by uncovering the laminar distribution of the field potential generators underlying the dominant delta waves in juveniles and adults. Our results suggest that field potentials are mostly generated by a pathway in deep layers, whereas other pathways mature later in middle layers and take over in adults. We suggest that a functional sensory-motor control relies on a delayed maturation and network integration of synaptic connections in middle layers.
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20
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Donovan CH, Badenhorst CA, Gruber AJ. Distributed Encoding of Reinforcement in Rat Cortico-Striatal-Limbic Networks. Neuroscience 2019; 413:169-82. [PMID: 31229632 DOI: 10.1016/j.neuroscience.2019.06.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/24/2019] [Accepted: 06/12/2019] [Indexed: 11/22/2022]
Abstract
Decision-making in the mammalian brain typically involves multiple brain structures within the midbrain, thalamus, striatum, limbic system, and cortex. Although task specific contributions of each brain region have been identified, neurons responding to reinforcement have been found throughout these structures. We sought to determine if any brain area, or cluster of areas, are the source of information, and if the fidelity of information varies among the areas. We recorded simultaneous field potentials (FPs) in rats from seven brain regions as they completed a binary choice task. The FPs of a 0.5 s window following reinforcement were given as input to a classifier that attempted to predict whether or not the rat received reward on each trial. The classifier correctly categorized reward on 77% of trials. Any region-specific signal could be omitted without lowering accuracy. Frequencies above 40 Hz and signals recorded later than 0.25 s following reinforcement were necessary to achieve this accuracy. Further, the classifier was able to predict reinforcement outcome above chance levels when using FPs from any single recorded brain region. Some combinations of structures, however, were more predictive than others. Analysis of FPs prior to reward revealed most regions reflected the prior probability of reward. Lastly, analyses of information flow suggested reinforcement information does not originate within a single structure of the network, within the resolution afforded by FP recordings. These data suggest reward delivery information is rapidly distributed non-uniformly across the network, and there is no canonical flow of information about reward events in the recorded structures.
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21
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Saez I, Lin J, Stolk A, Chang E, Parvizi J, Schalk G, Knight RT, Hsu M. Encoding of Multiple Reward-Related Computations in Transient and Sustained High-Frequency Activity in Human OFC. Curr Biol 2018; 28:2889-2899.e3. [PMID: 30220499 DOI: 10.1016/j.cub.2018.07.045] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/22/2018] [Accepted: 07/16/2018] [Indexed: 11/26/2022]
Abstract
Human orbitofrontal cortex (OFC) has long been implicated in value-based decision making. In recent years, convergent evidence from human and model organisms has further elucidated its role in representing reward-related computations underlying decision making. However, a detailed description of these processes remains elusive due in part to (1) limitations in our ability to observe human OFC neural dynamics at the timescale of decision processes and (2) methodological and interspecies differences that make it challenging to connect human and animal findings or to resolve discrepancies when they arise. Here, we sought to address these challenges by conducting multi-electrode electrocorticography (ECoG) recordings in neurosurgical patients during economic decision making to elucidate the electrophysiological signature, sub-second temporal profile, and anatomical distribution of reward-related computations within human OFC. We found that high-frequency activity (HFA) (70-200 Hz) reflected multiple valuation components grouped in two classes of valuation signals that were dissociable in temporal profile and information content: (1) fast, transient responses reflecting signals associated with choice and outcome processing, including anticipated risk and outcome regret, and (2) sustained responses explicitly encoding what happened in the immediately preceding trial. Anatomically, these responses were widely distributed in partially overlapping networks, including regions in the central OFC (Brodmann areas 11 and 13), which have been consistently implicated in reward processing in animal single-unit studies. Together, these results integrate insights drawn from human and animal studies and provide evidence for a role of human OFC in representing multiple reward computations.
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Affiliation(s)
- Ignacio Saez
- University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jack Lin
- University of California, Irvine, Irvine, CA 92697, USA
| | - Arjen Stolk
- University of California, Berkeley, Berkeley, CA 94720, USA
| | - Edward Chang
- University of California, San Francisco, San Francisco, CA 94143, USA
| | | | - Gerwin Schalk
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Robert T Knight
- University of California, Berkeley, Berkeley, CA 94720, USA.
| | - Ming Hsu
- University of California, Berkeley, Berkeley, CA 94720, USA.
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22
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Dietrich K, Bouter Y, Müller M, Bayer TA. Synaptic Alterations in Mouse Models for Alzheimer Disease-A Special Focus on N-Truncated Abeta 4-42. Molecules 2018; 23:E718. [PMID: 29561816 PMCID: PMC6017701 DOI: 10.3390/molecules23040718] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/16/2018] [Accepted: 03/19/2018] [Indexed: 11/29/2022] Open
Abstract
This commentary reviews the role of the Alzheimer amyloid peptide Aβ on basal synaptic transmission, synaptic short-term plasticity, as well as short- and long-term potentiation in transgenic mice, with a special focus on N-terminal truncated Aβ4-42. Aβ4-42 is highly abundant in the brain of Alzheimer's disease (AD) patients. It demonstrates increased neurotoxicity compared to full length Aβ, suggesting an important role in the pathogenesis of AD. Transgenic Tg4-42 mice, a model for sporadic AD, express human Aβ4-42 in Cornu Ammonis (CA1) neurons, and develop age-dependent hippocampal neuron loss and neurological deficits. In contrast to other transgenic AD mouse models, the Tg4-42 model exhibits synaptic hyperexcitability, altered synaptic short-term plasticity with no alterations in short- and long-term potentiation. The outcomes of this study are discussed in comparison with controversial results from other AD mouse models.
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Affiliation(s)
- Katharina Dietrich
- Division of Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Medical Center (UMG), Georg-August-University, von-Siebold-Strasse 5, 37075 Göttingen, Germany.
| | - Yvonne Bouter
- Division of Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Medical Center (UMG), Georg-August-University, von-Siebold-Strasse 5, 37075 Göttingen, Germany.
| | - Michael Müller
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Humboldtallee 23, 37073 Göttingen, Germany.
- Center for Physiology and Pathophysiology, Institute for Neuro- and Sense Physiology, University Medical Center (UMG), Georg-August-University, Humboldtallee 23, 37073 Göttingen, Germany.
| | - Thomas A Bayer
- Division of Molecular Psychiatry, Department of Psychiatry and Psychotherapy, University Medical Center (UMG), Georg-August-University, von-Siebold-Strasse 5, 37075 Göttingen, Germany.
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Rehnelt S, Malan D, Juhasz K, Wolters B, Doerr L, Beckler M, Kettenhofen R, Bohlen H, Bruegmann T, Sasse P. Frequency-Dependent Multi-Well Cardiotoxicity Screening Enabled by Optogenetic Stimulation. Int J Mol Sci 2017; 18:E2634. [PMID: 29211031 PMCID: PMC5751237 DOI: 10.3390/ijms18122634] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 11/28/2017] [Accepted: 11/30/2017] [Indexed: 11/17/2022] Open
Abstract
Side effects on cardiac ion channels causing lethal arrhythmias are one major reason for drug withdrawals from the market. Field potential (FP) recording from cardiomyocytes, is a well-suited tool to assess such cardiotoxic effects of drug candidates in preclinical drug development, but it is currently limited to the spontaneous beating of the cardiomyocytes and manual analysis. Herein, we present a novel optogenetic cardiotoxicity screening system suited for the parallel automated frequency-dependent analysis of drug effects on FP recorded from human-induced pluripotent stem cell-derived cardiomyocytes. For the expression of the light-sensitive cation channel Channelrhodopsin-2, we optimised protocols using virus transduction or transient mRNA transfection. Optical stimulation was performed with a new light-emitting diode lid for a 96-well FP recording system. This enabled reliable pacing at physiologically relevant heart rates and robust recording of FP. Thereby we detected rate-dependent effects of drugs on Na⁺, Ca2+ and K⁺ channel function indicated by FP prolongation, FP shortening and the slowing of the FP downstroke component, as well as generation of afterdepolarisations. Taken together, we present a scalable approach for preclinical frequency-dependent screening of drug effects on cardiac electrophysiology. Importantly, we show that the recording and analysis can be fully automated and the technology is readily available using commercial products.
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Affiliation(s)
- Susanne Rehnelt
- Institute of Physiology I, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
| | - Daniela Malan
- Institute of Physiology I, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
| | - Krisztina Juhasz
- Nanion Technologies GmbH, 80636 Munich, Germany.
- Present address: Institute for Nanoelectronics, Department of Electrical Engineering and Information Technology, Technische Universität München, 80339 Munich, Germany.
| | - Benjamin Wolters
- Part of the Ncardia Group, Axiogenesis AG, 50829 Cologne, Germany.
| | - Leo Doerr
- Nanion Technologies GmbH, 80636 Munich, Germany.
| | | | - Ralf Kettenhofen
- Part of the Ncardia Group, Axiogenesis AG, 50829 Cologne, Germany.
| | - Heribert Bohlen
- Part of the Ncardia Group, Axiogenesis AG, 50829 Cologne, Germany.
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
- Research Training Group 1873, University of Bonn, 53127 Bonn, Germany.
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, 53127 Bonn, Germany.
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Kajikawa Y, Smiley JF, Schroeder CE. Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex. J Neurosci 2017; 37:10139-53. [PMID: 28924008 DOI: 10.1523/JNEUROSCI.3800-16.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 07/21/2017] [Indexed: 01/02/2023] Open
Abstract
Prior studies have reported "local" field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be "contaminated" by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such "far-field" activity, in addition to, or in absence of, local synaptic responses.SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is problematic as the default assumption is that FPs originate from local activity, and thus are termed "local" (LFP). We examine this general problem in the context of previously reported face-evoked FPs in macaque auditory cortex. Our findings suggest that face-FPs are indeed generated in the underlying inferotemporal cortex and volume-conducted to the auditory cortex. The note of caution raised by these findings is of particular importance for studies that seek to assign FP/LFP recordings to specific cortical layers.
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25
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Gulyás AI, Freund TF, Káli S. The Effects of Realistic Synaptic Distribution and 3D Geometry on Signal Integration and Extracellular Field Generation of Hippocampal Pyramidal Cells and Inhibitory Neurons. Front Neural Circuits 2016; 10:88. [PMID: 27877113 PMCID: PMC5099150 DOI: 10.3389/fncir.2016.00088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 10/17/2016] [Indexed: 12/02/2022] Open
Abstract
In vivo and in vitro multichannel field and somatic intracellular recordings are frequently used to study mechanisms of network pattern generation. When interpreting these data, neurons are often implicitly considered as electrotonically compact cylinders with a homogeneous distribution of excitatory and inhibitory inputs. However, the actual distributions of dendritic length, diameter, and the densities of excitatory and inhibitory input are non-uniform and cell type-specific. We first review quantitative data on the dendritic structure and synaptic input and output distribution of pyramidal cells (PCs) and interneurons in the hippocampal CA1 area. Second, using multicompartmental passive models of four different types of neurons, we quantitatively explore the effect of differences in dendritic structure and synaptic distribution on the errors and biases of voltage clamp measurements of inhibitory and excitatory postsynaptic currents. Finally, using the 3-dimensional distribution of dendrites and synaptic inputs we calculate how different inhibitory and excitatory inputs contribute to the generation of local field potential in the hippocampus. We analyze these effects at different realistic background activity levels as synaptic bombardment influences neuronal conductance and thus the propagation of signals in the dendritic tree. We conclude that, since dendrites are electrotonically long and entangled in 3D, somatic intracellular and field potential recordings miss the majority of dendritic events in some cell types, and thus overemphasize the importance of perisomatic inhibitory inputs and belittle the importance of complex dendritic processing. Modeling results also suggest that PCs and inhibitory neurons probably use different input integration strategies. In PCs, second- and higher-order thin dendrites are relatively well-isolated from each other, which may support branch-specific local processing as suggested by studies of active dendritic integration. In the electrotonically compact parvalbumin- and cholecystokinincontaining interneurons, synaptic events are visible in the whole dendritic arbor, and thus the entire dendritic tree may form a single integrative element. Calretinin-containing interneurons were found to be electrotonically extended, which suggests the possibility of complex dendritic processing in this cell type. Our results also highlight the need for the integration of methods that allow the measurement of dendritic processes into studies of synaptic interactions and dynamics in neural networks.
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Affiliation(s)
- Attila I Gulyás
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Tamás F Freund
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Szabolcs Káli
- Laboratory of Cerebral Cortex Research, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
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26
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Goldwyn JH, Rinzel J. Neuronal coupling by endogenous electric fields: cable theory and applications to coincidence detector neurons in the auditory brain stem. J Neurophysiol 2016; 115:2033-51. [PMID: 26823512 PMCID: PMC4869512 DOI: 10.1152/jn.00780.2015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 01/27/2016] [Indexed: 11/22/2022] Open
Abstract
The ongoing activity of neurons generates a spatially and time-varying field of extracellular voltage (Ve). This Ve field reflects population-level neural activity, but does it modulate neural dynamics and the function of neural circuits? We provide a cable theory framework to study how a bundle of model neurons generates Ve and how this Ve feeds back and influences membrane potential (Vm). We find that these "ephaptic interactions" are small but not negligible. The model neural population can generate Ve with millivolt-scale amplitude, and this Ve perturbs the Vm of "nearby" cables and effectively increases their electrotonic length. After using passive cable theory to systematically study ephaptic coupling, we explore a test case: the medial superior olive (MSO) in the auditory brain stem. The MSO is a possible locus of ephaptic interactions: sounds evoke large (millivolt scale)Vein vivo in this nucleus. The Ve response is thought to be generated by MSO neurons that perform a known neuronal computation with submillisecond temporal precision (coincidence detection to encode sound source location). Using a biophysically based model of MSO neurons, we find millivolt-scale ephaptic interactions consistent with the passive cable theory results. These subtle membrane potential perturbations induce changes in spike initiation threshold, spike time synchrony, and time difference sensitivity. These results suggest that ephaptic coupling may influence MSO function.
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Affiliation(s)
- Joshua H Goldwyn
- Center for Neural Science, New York University, New York, New York; Courant Institute of Mathematical Sciences, New York University, New York, New York; and Department of Mathematics, Ohio State University, Columbus, Ohio
| | - John Rinzel
- Center for Neural Science, New York University, New York, New York; Courant Institute of Mathematical Sciences, New York University, New York, New York; and
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27
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Park EH, Burghardt NS, Dvorak D, Hen R, Fenton AA. Experience-Dependent Regulation of Dentate Gyrus Excitability by Adult-Born Granule Cells. J Neurosci 2015; 35:11656-66. [PMID: 26290242 DOI: 10.1523/JNEUROSCI.0885-15.2015] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Behavioral studies have established a role for adult-born dentate granule cells in discriminating between similar memories. However, it is unclear how these cells mediate memory discrimination. Excitability is enhanced in maturing adult-born neurons, spurring the hypothesis that the activity of these cells "directly" encodes and stores memories. An alternative hypothesis posits that maturing neurons "indirectly" contribute to memory encoding by regulating excitation-inhibition balance. We evaluated these alternatives by using dentate-sensitive active place avoidance tasks to assess experience-dependent changes in dentate field potentials in the presence and absence of neurogenesis. Before training, X-ray ablation of adult neurogenesis-reduced dentate responses to perforant-path stimulation and shifted EPSP-spike coupling leftward. These differences were unchanged after place avoidance training with the shock zone in the initial location, which both groups learned to avoid equally well. In contrast, sham-treated mice decreased dentate responses and shifted EPSP-spike coupling leftward after the shock zone was relocated, whereas X-irradiated mice failed to show these changes in dentate function and were impaired on this test of memory discrimination. During place avoidance, excitation-inhibition coupled neural synchrony in dentate local field potentials was reduced in X-irradiated mice, especially in the θ band. The difference was most prominent during conflict learning, which is impaired in the X-irradiated mice. These findings indicate that maturing adult-born neurons regulate both functional network plasticity in response to memory discrimination and dentate excitation-inhibition coordination. The most parsimonious interpretation of these results is that adult neurogenesis indirectly regulates hippocampal information processing. SIGNIFICANCE STATEMENT Adult-born neurons in the hippocampal dentate gyrus are important for flexibly using memories, but the mechanism is controversial. Using tests of hippocampus-dependent place avoidance learning and dentate electrophysiology in mice with normal or ablated neurogenesis, we find that maturing adult-born neurons are crucial only when memory must be used flexibly, and that these neurons regulate dentate gyrus synaptic and spiking responses to neocortical input rather than directly storing information, as has been proposed. A day after learning to avoid the initial or changed locations of shock, the dentate synaptic responses are enhanced or suppressed, respectively, unlike mice lacking adult neurogenesis, which did not change. The contribution of adult neurogenesis to memory is indirect, by regulating dentate excitation-inhibition coupling.
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28
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Qu Y, Vargas HM. Proarrhythmia Risk Assessment in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes Using the Maestro MEA Platform. Toxicol Sci 2015; 147:286-95. [PMID: 26117837 DOI: 10.1093/toxsci/kfv128] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Evaluation of stem cell-derived cardiomyocytes (SC-CM) using multi-electrode array (MEA) has attracted attention as a novel model to detect drug-induced arrhythmia. An experiment was conducted to determine if MEA recording from human induced pluripotent SC-CM (hiPSC-CM) could assess proarrhythmic risk. Ten hERG blockers, 4 Na(+) blockers, and 1 IKs blocker were evaluated blindly. Eight drugs are associated with Torsades de Pointes (TdP) and 4 are not. Multiple parameters, including field potential duration (FPD), Na(+) slope, Na(+) amplitude, beat rate (BR), and early after-depolarization (EAD) were recorded. Minimum effective concentrations (MEC) that elicited a significant change were calculated. Our results determined that FPD and EAD were unable to distinguish torsadogenic from benign compounds, Na(+) slope and amplitude could not differentiate Na(+) channel blockade from hERG blockade, BR had an inconsistent response to pharmacological treatment, and that hiPSC-CM were, in general, insensitive to IKs inhibition. A ratio was calculated that relates MEC for evoking FPD prolongation, or triggering EAD, to the human therapeutic unbound Cmax (MEC/Cmax). The key finding was that the ratio was sensitive, but specificity was low. Consistently, the ratio had high positive predictive value and low negative predictive value. In conclusion, MEA recordings of hiPSC-CM were sensitive for FPD and EAD detection, but unable to distinguish agents with low- and high-risk for TdPs. Although some published reports suggested great potential for MEA recordings in hSC-CM to assess preclinical cardiac toxicity, the current evaluation implies that this model would have a high false-positive rate in regard to proarrhythmic risk.
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Affiliation(s)
- Yusheng Qu
- Integrated Discovery and Safety Pharmacology, Amgen Inc., Thousand Oaks, California 91320
| | - Hugo M Vargas
- Integrated Discovery and Safety Pharmacology, Amgen Inc., Thousand Oaks, California 91320
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29
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Hånell A, Greer JE, Jacobs KM. Increased Network Excitability Due to Altered Synaptic Inputs to Neocortical Layer V Intact and Axotomized Pyramidal Neurons after Mild Traumatic Brain Injury. J Neurotrauma 2015; 32:1590-8. [PMID: 25789412 DOI: 10.1089/neu.2014.3592] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mild traumatic brain injury (mTBI) can produce long lasting cognitive dysfunction. There is typically no cell death and only diffuse structural injury after mTBI. Thus, functional changes in intact neurons may contribute to symptoms. We have previously shown altered intrinsic properties of axotomized and intact neurons within 2 d after a central fluid percussion injury in mice expressing yellow fluorescent protein (YFP) that allow identification of axonal state prior to recording. Here, whole-cell patch clamp recordings were used to examine synaptic properties of YFP(+) layer V pyramidal neurons. An increased frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs) was recorded from axotomized neurons at 1 d and intact neurons at 2 d after injury, likely reflecting an increased number of afferents. This also was reflected in the increased amplitude of the EPSC evoked by local extracellular stimulation for all neurons from injured cortex and increased likelihood of producing an action potential for intact cells. Field potentials recorded in superficial layers after online deep layer stimulation contained a single negative peak in controls but multiple negative peaks in injured tissue. The amplitude of this evoked negativity was significantly larger than controls over a series of stimulus intensities at both the 1 d and 2 d survival times. Interictal-like spikes never occurred in the field potential recordings from controls but were observed in 20-80% of stimulus presentations in injured cortex. Together, these results suggest an overall increase in network excitability and the production of particularly powerful (intact) neurons that have both increased intrinsic and synaptic excitability.
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Affiliation(s)
- Anders Hånell
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
| | - John E Greer
- 2 Department of Neurosurgery, Virginia Commonwealth University , Richmond, Virginia
| | - Kimberle M Jacobs
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
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Sinning A, Liebmann L, Hübner CA. Disruption of Slc4a10 augments neuronal excitability and modulates synaptic short-term plasticity. Front Cell Neurosci 2015; 9:223. [PMID: 26136660 PMCID: PMC4468864 DOI: 10.3389/fncel.2015.00223] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 05/27/2015] [Indexed: 11/13/2022] Open
Abstract
Slc4a10 is a Na+-coupled Cl−-HCO3− exchanger, which is expressed in principal and inhibitory neurons as well as in choroid plexus epithelial cells of the brain. Slc4a10 knockout (KO) mice have collapsed brain ventricles and display an increased seizure threshold, while heterozygous deletions in man have been associated with idiopathic epilepsy and other neurological symptoms. To further characterize the role of Slc4a10 for network excitability, we compared input-output relations as well as short and long term changes of evoked field potentials in Slc4a10 KO and wildtype (WT) mice. While responses of CA1 pyramidal neurons to stimulation of Schaffer collaterals were increased in Slc4a10 KO mice, evoked field potentials did not differ between genotypes in the stratum radiatum or the neocortical areas analyzed. Paired pulse facilitation was diminished in the hippocampus upon disruption of Slc4a10. In the neocortex paired pulse depression was increased. Though short term plasticity is modulated via Slc4a10, long term potentiation appears independent of Slc4a10. Our data support that Slc4a10 dampens neuronal excitability and thus sheds light on the pathophysiology of SLC4A10 associated pathologies.
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Affiliation(s)
- Anne Sinning
- Institute of Human Genetics, University Hospital Jena, Friedrich Schiller University Jena Jena, Germany ; Institute of Physiology, University Medical Center of the Johannes Gutenberg University Mainz, Germany
| | - Lutz Liebmann
- Institute of Human Genetics, University Hospital Jena, Friedrich Schiller University Jena Jena, Germany
| | - Christian A Hübner
- Institute of Human Genetics, University Hospital Jena, Friedrich Schiller University Jena Jena, Germany
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31
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Skelin I, Needham MA, Molina LM, Metz GAS, Gruber AJ. Multigenerational prenatal stress increases the coherence of brain signaling among cortico-striatal-limbic circuits in adult rats. Neuroscience 2015; 289:270-8. [PMID: 25595989 DOI: 10.1016/j.neuroscience.2015.01.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/23/2014] [Accepted: 01/04/2015] [Indexed: 11/28/2022]
Abstract
Prenatal stress (PNS) is a significant risk factor for the development of psychopathology in adulthood such as anxiety, depression, schizophrenia and addiction. Animal models of PNS resemble many of the effects of PNS on humans and provide a means to study the accumulated effects of PNS over several generations on brain function. Here, we examined how mild PNS delivered during the third week in utero over four consecutive generations affects behavioral flexibility and functional signaling among cortical and limbic structures. These multi-generational prenatally stressed (MGPNS) rats were not impaired on an odor-cued reversal learning task as compared to control animals. Unilateral field potential (FP) recordings from the medial prefrontal cortex, basolateral amygdala, ventral hippocampus, and striatal territories revealed widespread differences in brain signaling between these groups during the odor sampling phase of the task. The FP power was significantly lower in most structures across most frequency bands in MGPNS animals, and the relative increase in power from baseline during the task was lower for the beta band (12-30Hz) in MGPNS animals as compared to controls. The coherence of FPs between brain regions, however, was much higher in MGPNS animals among all structures and for most frequency bands. We propose that this pattern of changes in brain signaling reflects a simplification of network processing, which is consistent with reports of reduced spine density and dendritic complexity in the brains of animals receiving PNS. Our data support the proposal that recurrent ancestral stress leads to adaptations in the brain, and that these may confer adaptive behavior in some circumstances as compared to single-generation PNS.
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Affiliation(s)
- I Skelin
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - M A Needham
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - L M Molina
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - G A S Metz
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - A J Gruber
- Canadian Centre for Behavioural Neuroscience, Department of Neuroscience, University of Lethbridge, Lethbridge, AB, Canada.
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32
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Kajikawa Y, Schroeder CE. Generation of field potentials and modulation of their dynamics through volume integration of cortical activity. J Neurophysiol 2014; 113:339-51. [PMID: 25274348 DOI: 10.1152/jn.00914.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Field potentials (FPs) recorded within the brain, often called "local field potentials" (LFPs), are useful measures of net synaptic activity in a neuronal ensemble. However, due to volume conduction, FPs spread beyond regions of underlying synaptic activity, and thus an "LFP" signal may not accurately reflect the temporal patterns of synaptic activity in the immediately surrounding neuron population. To better understand the physiological processes reflected in FPs, we explored the relationship between the FP and its membrane current generators using current source density (CSD) analysis in conjunction with a volume conductor model. The model provides a quantitative description of the spatiotemporal summation of immediate local and more distant membrane currents to produce the FP. By applying the model to FPs in the macaque auditory cortex, we have investigated a critical issue that has broad implications for FP research. We have shown that FP responses in particular cortical layers are differentially susceptible to activity in other layers. Activity in the supragranular layers has the strongest contribution to FPs in other cortical layers, and infragranular FPs are most susceptible to contributions from other layers. To define the physiological processes generating FPs recorded in loci of relatively weak synaptic activity, strong effects produced by synaptic events in the vicinity have to be taken into account. While outlining limitations and caveats inherent to FP measurements, our results also suggest specific peak and frequency band components of FPs can be related to activity in specific cortical layers. These results may help improving the interpretability of FPs.
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Affiliation(s)
- Yoshinao Kajikawa
- Cognitive Neuroscience and Schizophrenia Program, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York; and
| | - Charles E Schroeder
- Cognitive Neuroscience and Schizophrenia Program, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York; and Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York
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Long LL, Hinman JR, Chen CMA, Stevenson IH, Read HL, Escabi MA, Chrobak JJ. Novel acoustic stimuli can alter locomotor speed to hippocampal theta relationship. Hippocampus 2014; 24:1053-8. [PMID: 24866396 DOI: 10.1002/hipo.22308] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2014] [Indexed: 02/04/2023]
Abstract
Hippocampal theta (6-12 Hz) plays a critical role in synchronizing the discharge of action potentials, ultimately orchestrating individual neurons into large-scale ensembles. Alterations in theta dynamics may reflect variations in sensorimotor integration, the flow of sensory input, and/or cognitive processing. Previously we have investigated septotemporal variation in the locomotor speed to theta amplitude relationship as well as how that relationship is systematically altered as a function of novel, physical space. In the present study, we ask, beyond physical space, whether persistent and passive sound delivery can alter septal theta local field potential rhythm dynamics. Results indicate pronounced alterations in the slope of the speed to theta amplitude relationship as a function of sound presentation and location. Further, this reduction in slope habituates across days. The current findings highlight that moment-to-moment alterations in theta amplitude is a rich dynamic index that is quantitatively related to both alterations in motor behavior and sensory experience. The implications of these phenomena are discussed with respect to emergent cognitive functions subserved by hippocampal circuits.
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Affiliation(s)
- Lauren L Long
- Department of Psychology, University of Connecticut, Storrs, Connecticut
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Abstract
Rats generate sweeping whisker movements in order to explore their environments and identify objects. In somatosensory pathways, neuronal activity is modulated by the frequency of whisker vibration. However, the potential role of rhythmic neuronal activity in the cerebral processing of sensory signals and its mechanism remain unclear. Here, we showed that rhythmic vibrissal stimulation with short duration in anesthetized rats resulted in an increase or decrease in the amplitude of somatosensory-evoked potentials (SEPs) in the contralateral barrel cortex. The plastic change of the SEPs was frequency dependent and long lasting. The long-lasting enhancement of the vibrissa-to-cortex evoked response was side- but not barrel-specific. Local application of dl-2-amino-5-phosphonopentanoic acid into the barrel cortex revealed that this vibrissa-to-cortex long-term plasticity in adult rats was N-methyl-d-aspartate receptor-dependent. Most interestingly, whisker trimming through postnatal day (P)1-7 but not P29-35 impaired the long-term plasticity induced by 100 Hz vibrissal stimulation. The short period of rhythmic vibrissal stimulation did not induce long-lasting plasticity of field potentials in the thalamus. In conclusion, our results suggest that natural rhythmic whisker activity modifies sensory information processing in cerebral cortex, providing further insight into sensory perception.
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Affiliation(s)
- Yong Han
- Department of Neurobiology and Physiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Ming-De Huang
- Department of Neurobiology and Physiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Man-Li Sun
- Department of Neurobiology and Physiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Shumin Duan
- Department of Neurobiology and Physiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yan-Qin Yu
- Department of Neurobiology and Physiology, Key Laboratory of Medical Neurobiology of Ministry of Health of China, Zhejiang Province Key Laboratory of Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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Wang Y, Wei W, Wang Y, Dong J, Song B, Min H, Teng W, Chen J. Neurotoxicity of developmental hypothyroxinemia and hypothyroidism in rats: Impairments of long-term potentiation are mediated by phosphatidylinositol 3-kinase signaling pathway. Toxicol Appl Pharmacol 2013; 271:257-65. [PMID: 23707767 DOI: 10.1016/j.taap.2013.04.034] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 12/15/2022]
Abstract
Neurotoxicity of iodine deficiency-induced hypothyroidism during developmental period results in serious impairments of brain function, such as learning and memory. These impairments are largely irreversible, and the underlying mechanisms remain unclear. In addition to hypothyroidism, iodine deficiency may cause hypothyroxinemia, a relatively subtle form of thyroid hormone deficiency. Neurotoxicity of developmental hypothyroxinemia also potentially impairs learning and memory. However, more direct evidence of the associations between developmental hypothyroxinemia and impairments of learning and memory should be provided, and the underlying mechanisms remain to be elucidated. Thus, in the present study, we investigated the effects of developmental hypothyroxinemia and hypothyroidism on long-term potentiation (LTP), a widely accepted cellular model of learning and memory, in the hippocampal CA1 region. The activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway - a pathway closely associated with synaptic plasticity and learning and memory - was also investigated. Wistar rats were treated with iodine deficient diet or methimazole (MMZ) to induce developmental hypothyroxinemia or hypothyroidism. The results showed that developmental hypothyroxinemia caused by mild iodine deficiency and developmental hypothyroidism caused by severe iodine deficiency or MMZ significantly reduced the field-excitatory postsynaptic potential (f-EPSP) slope and the population spike (PS) amplitude. Decreased activation of the PI3K signaling pathway was also observed in rats subjected to developmental hypothyroxinemia or hypothyroidism. Our results may support the hypothesis that neurotoxicity of both developmental hypothyroxinemia and hypothyroidism causes damages to learning and memory. Our results also suggest that decreased activation of the PI3K signaling pathway may contribute to impairments of LTP caused by neurotoxicity of both developmental hypothyroxinemia and hypothyroidism.
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Affiliation(s)
- Yi Wang
- Department of Occupational and Environmental Health, School of Public Health, China Medical University, Shenyang, PR China
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Himmel HM. Drug-induced functional cardiotoxicity screening in stem cell-derived human and mouse cardiomyocytes: effects of reference compounds. J Pharmacol Toxicol Methods 2013; 68:97-111. [PMID: 23702537 DOI: 10.1016/j.vascn.2013.05.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 05/10/2013] [Accepted: 05/10/2013] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Early prediction of drug-induced functional cardiotoxicity requires robust in-vitro systems suitable for medium/high throughput and easily accessible cardiomyocytes with defined reproducible properties. The xCELLigence Cardio system uses 96-well plates with interdigitated electrodes that detect the impedance changes of rhythmic contractions of stem cell-derived cardiomyocyte (SC-CM) layers. Here, we report on our initial screening experience in comparison to established (multi)cellular and in-vivo models. METHODS Impedance signals from human iPSC-CM (iCells™) and mouse eSC-CM (Cor.At™) were analyzed for contraction amplitude (CA) and duration, rise/fall time, beating rate (BR) and irregularity. RESULTS Following solution exchange, impedance signals re-approximated steady-state conditions after about 2 (Cor.At™) and 3h (iCells™); these time points were used to analyze drug effects. The solvent DMSO (≤1%) hardly influenced contraction parameters in Cor.At™, whereas in iCells™ DMSO (>0.1%) reduced CA and enhanced BR. The selective hERG K⁺ channel blockers E-4031 and dofetilide reduced CA and accelerated BR (≥30 nM) according to the analysis software. The latter, however, was due to burst-like contractions (300 nM) that could be detected only by visual inspection of recordings, and were more pronounced in Cor.At™ as in iCells™. In cardiac myocytes and tissue preparations, however, E4031 and dofetilide have been reported to increase cell shortening and contractile force and to reduce BR. Compounds (pentamidine, HMR1556, ATX2, TTX, and verapamil) with other mechanisms of action were also investigated; their effects differed partially between cell lines (e.g. TTX) and compared to established (multi)cellular models (e.g. HMR1556, ouabain). CONCLUSION Mouse and human stem cell-derived cardiomyocytes respond differently to drugs and these responses occasionally also differ from those originating from established in-vitro and in-vivo models. Hence, drug-induced cardiotoxic effects may be detected with this system, however, the predictive or even translational value of results is considered limited and not yet firmly established.
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Isaeva E, Isaev D, Holmes GL. Alteration of synaptic plasticity by neonatal seizures in rat somatosensory cortex. Epilepsy Res 2013; 106:280-3. [PMID: 23623846 DOI: 10.1016/j.eplepsyres.2013.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/11/2013] [Accepted: 03/27/2013] [Indexed: 10/26/2022]
Abstract
Seizures in newborns are associated with a high risk for subsequent epilepsy and adverse neurodevelopmental consequences. Understanding the mechanisms by which neonatal seizures adversely disturb the immature brain is important in developing therapeutic strategies. Using the convulsant agent flurothyl to mimic repetitive neonatal seizures we show that early-life seizures result in long-term alteration in the maintenance phase of long-term potentiation (LTP) in layer IV to layer II/III synapses of the somatosensory cortex without alteration of basal synaptic transmission, the induction phase of LTP and short-term depression. Such alterations may have a role in functional deficits seen following neonatal seizures.
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Affiliation(s)
- Elena Isaeva
- Department of Neurology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.
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Abstract
An emerging literature suggests that the medial prefrontal cortex (mPFC) is crucial for the ability to track behavioral outcomes over time and has a critical role in successful foraging. Here, we examine this issue by analyzing changes in neuronal spike activity and local field potentials in the rat mPFC in relation to the consumption of rewarding stimuli. Using multi-electrode recording methods, we simultaneously recorded from ensembles of neurons and field potentials in the mPFC during the performance of an operant-delayed alternation task and a variable-interval licking procedure. In both tasks, we found that consummatory behavior (licking) activates many mPFC neurons and is associated with theta-band phase locking by mPFC field potentials. Many neurons that were modulated by the delivery of reward were also modulated when rats emitted bouts of licks during the period of consumption. The majority of these licking-modulated neurons were found in the rostral part of the prelimbic cortex, a region that is heavily interconnected with the gustatory insular cortex and projects to subcortical feeding-related centers. Based on the tight coupling between spike activity, theta-band phase locking, and licking behavior, we suggest that reward-related activity in the mPFC is driven by consummatory behavior.
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Affiliation(s)
- Nicole K. Horst
- The John B. Pierce LaboratoryNew Haven, CT, USA
- Interdepartmental Neuroscience Program, Yale University School of MedicineNew Haven, CT, USA
| | - Mark Laubach
- The John B. Pierce LaboratoryNew Haven, CT, USA
- Department of Neurobiology, Yale University School of MedicineNew Haven, CT, USA
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Fendyur A, Spira ME. Toward on-chip, in-cell recordings from cultured cardiomyocytes by arrays of gold mushroom-shaped microelectrodes. Front Neuroeng 2012; 5:21. [PMID: 22936913 PMCID: PMC3426852 DOI: 10.3389/fneng.2012.00021] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 08/05/2012] [Indexed: 11/13/2022]
Abstract
Cardiological research greatly rely on the use of cultured primary cardiomyocytes (CMs). The prime methodology to assess CM network electrophysiology is based on the use of extracellular recordings by substrate-integrated planar Micro-Electrode Arrays (MEAs). Whereas this methodology permits simultaneous, long-term monitoring of the CM electrical activity, it limits the information to extracellular field potentials (FPs). The alternative method of intracellular action potentials (APs) recordings by sharp- or patch-microelectrodes is limited to a single cell at a time. Here, we began to merge the advantages of planar MEA and intracellular microelectrodes. To that end we cultured rat CM on micrometer size protruding gold mushroom-shaped microelectrode (gMμEs) arrays. Cultured CMs engulf the gMμE permitting FPs recordings from individual cells. Local electroporation of a CM converts the extracellular recording configuration to attenuated intracellular APs with shape and duration similar to those recorded intracellularly. The procedure enables to simultaneously record APs from an unlimited number of CMs. The electroporated membrane spontaneously recovers. This allows for repeated recordings from the same CM a number of times (>8) for over 10 days. The further development of CM-gMμE configuration opens up new venues for basic and applied biomedical research.
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Affiliation(s)
- Anna Fendyur
- The Alexander Silberman Life Sciences Institute and the Harvey M. Kruger Family Center for Nanoscience, The Hebrew University of Jerusalem Jerusalem, Israel
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Himmel HM, Bussek A, Hoffmann M, Beckmann R, Lohmann H, Schmidt M, Wettwer E. Field and action potential recordings in heart slices: correlation with established in vitro and in vivo models. Br J Pharmacol 2012; 166:276-96. [PMID: 22074238 PMCID: PMC3415654 DOI: 10.1111/j.1476-5381.2011.01775.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 09/23/2011] [Accepted: 09/29/2011] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Action potential (AP) recordings in ex vivo heart preparations constitute an important component of the preclinical cardiac safety assessment according to the ICH S7B guideline. Most AP measurement models are sensitive, predictive and informative but suffer from a low throughput. Here, effects of selected anti-arrhythmics (flecainide, quinidine, atenolol, sotalol, dofetilide, nifedipine, verapamil) on field/action potentials (FP/AP) of guinea pig and rabbit ventricular slices are presented and compared with data from established in vitro and in vivo models. EXPERIMENTAL APPROACH Data from measurements of membrane currents (hERG, I(Na) ), AP/FP (guinea pig and rabbit ventricular slices), AP (rabbit Purkinje fibre), haemodynamic/ECG parameters (conscious, telemetered dog) were collected, compared and correlated to complementary published data (focused literature search). KEY RESULTS The selected anti-arrhythmics, flecainide, quinidine, atenolol, sotalol, dofetilide, nifedipine and verapamil, influenced the shape of AP/FP of guinea pig and rabbit ventricular slices in a manner similar to that observed for rabbit PF. The findings obtained from slice preparations are in line with measurements of membrane currents in vitro, papillary muscle AP in vitro and haemodynamic/ECG parameters from conscious dogs in vivo, and were also corroborated by published data. CONCLUSION AND IMPLICATIONS FP and AP recordings from heart slices correlated well with established in vitro and in vivo models in terms of pharmacology and predictability. Heart slice preparations yield similar results as papillary muscle but offer enhanced throughput for mechanistic investigations and may substantially reduce the use of laboratory animals.
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Nelson TE, Hao C, Manos J, Ransohoff R, Gruol DL. Altered hippocampal synaptic transmission in transgenic mice with astrocyte-targeted enhanced CCL2 expression. Brain Behav Immun 2011; 25 Suppl 1:S106-19. [PMID: 21356306 PMCID: PMC4467826 DOI: 10.1016/j.bbi.2011.02.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 02/18/2011] [Accepted: 02/18/2011] [Indexed: 01/17/2023] Open
Abstract
Elevated expression of neuroinflammatory factors in the central nervous system (CNS) contributes to the cognitive impairment in CNS disorders such as injury, disease and neurodegenerative disorders. However, information on the role of specific neuroimmune factors in normal and abnormal CNS function is limited. In this study, we investigated the effects of chronic exposure to the chemokine CCL2 on hippocampal synaptic function at the Schaffer collateral-CA1 synapse, a synapse that is known to play an important role in cognitive functions such as memory and learning. Synaptic function was measured in vitro using hippocampal slices obtained from transgenic mice that express elevated levels of CCL2 in the CNS through astrocyte expression and their non-transgenic littermate controls. Extracellular field potential electrophysiological recordings showed a significant reduction in the magnitude of synaptic responses in hippocampal slices from the CCL2 transgenic mice compared with slices from non-transgenic littermate controls. Two forms of short-term synaptic plasticity (post-tetanic potentiation and short-term potentiation) thought to be important cellular mechanisms of short-term memory were enhanced in hippocampal slices from CCL2 transgenic mice compared to non-transgenic hippocampal slices, whereas long-term synaptic plasticity (LTP), which is critical to long-term memory formation, was not altered. Western blot analysis of hippocampus from the CCL2 transgenic mice and non-transgenic mice showed no change in level of neuronal specific enolase, a neuronal specific protein, GFAP, an astrocyte specific protein, and several synaptic proteins compared with non-transgenic littermate controls. These results show that CCL2, which is known to be chronically produced at elevated levels within the CNS in a number of CNS disorders, can significantly alter hippocampal function and implicate a role for CCL2 in the cognitive dysfunction associated with these CNS disorders.
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Affiliation(s)
- Thomas E. Nelson
- Molecular and Integrative Neurosciences Dept., The Scripps Research Institute, La Jolla, CA, USA
| | - Christine Hao
- Molecular and Integrative Neurosciences Dept., The Scripps Research Institute, La Jolla, CA, USA
| | - Jessica Manos
- Molecular and Integrative Neurosciences Dept., The Scripps Research Institute, La Jolla, CA, USA
| | - R.M. Ransohoff
- Neuroinflammation Research Center, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Donna L. Gruol
- Molecular and Integrative Neurosciences Dept., The Scripps Research Institute, La Jolla, CA, USA
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Abstract
Examining neuronal network activity in freely behaving animals is advantageous for probing the function of the vertebrate central nervous system. Here, we describe a simple, robust technique for monitoring the activity of neural circuits in unfettered, freely behaving zebrafish (Danio rerio). Zebrafish respond to unexpected tactile stimuli with short- or long-latency escape behaviors, which are mediated by distinct neural circuits. Using dipole electrodes immersed in the aquarium, we measured electric field potentials generated in muscle during short- and long-latency escapes. We found that activation of the underlying neural circuits produced unique field potential signatures that are easily recognized and can be repeatedly monitored. In conjunction with behavioral analysis, we used this technique to track changes in the pattern of circuit activation during the first week of development in animals whose trigeminal sensory neurons were unilaterally ablated. One day post-ablation, the frequency of short- and long-latency responses was significantly lower on the ablated side than on the intact side. Three days post-ablation, a significant fraction of escapes evoked by stimuli on the ablated side was improperly executed, with the animal turning towards rather than away from the stimulus. However, the overall response rate remained low. Seven days post-ablation, the frequency of escapes increased dramatically and the percentage of improperly executed escapes declined. Our results demonstrate that trigeminal ablation results in rapid reconfiguration of the escape circuitry, with reinnervation by new sensory neurons and adaptive changes in behavior. This technique is valuable for probing the activity, development, plasticity and regeneration of neural circuits under natural conditions.
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Affiliation(s)
- Fadi A. Issa
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1751, USA
| | - Georgeann O'Brien
- Department of Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, CA 90095-1606, USA
| | - Petronella Kettunen
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095-1568, USA
| | - Alvaro Sagasti
- Department of Molecular, Cell, and Developmental Biology, UCLA, Los Angeles, CA 90095-1606, USA
| | - David L. Glanzman
- Department of Integrative Biology and Physiology, UCLA, Los Angeles, CA 90095-1568, USA
| | - Diane M. Papazian
- Department of Physiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1751, USA
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Abstract
Intracellular recording and computational modelling suggest that interactions of subthreshold membrane potential oscillation frequency in different dendritic branches of entorhinal cortex stellate cells could underlie the functional coding of continuous dimensions of space and time. Among other things, these interactions could underlie properties of grid cell field spacing. The relationship between experimental data on membrane potential oscillation frequency (f) and grid cell field spacing (G) indicates a constant scaling factor H = fG. This constant scaling factor between temporal oscillation frequency and spatial periodicity provides a starting constraint that is used to derive the model of Burgess et al. (Hippocampus, 2007). This model provides a consistent quantitative link between single cell physiological properties and properties of spiking units in awake behaving animals. Further properties and predictions of this model about single cell and network physiological properties are analyzed. In particular, the model makes quantitative predictions about the change in membrane potential, single cell oscillation frequency, and network oscillation frequency associated with speed of movement, about the independence of single cell properties from network theta rhythm oscillations, and about the effect of variations in initial oscillatory phase on the pattern of grid cell firing fields. These same mechanisms of subthreshold oscillations may play a more general role in memory function, by providing a method for learning arbitrary time intervals in memory sequences.
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Affiliation(s)
- Michael E. Hasselmo
- Center for Memory and Brain and Program in Neuroscience, Boston University, 2 Cummington St., Boston, Massachusetts 02215, (617) 353-1397, FAX: (617) 358-3269,
| | - Lisa M. Giocomo
- Center for Memory and Brain and Program in Neuroscience, Boston University, 2 Cummington St., Boston, Massachusetts 02215, (617) 353-1397, FAX: (617) 358-3269,
| | - Eric A. Zilli
- Center for Memory and Brain and Program in Neuroscience, Boston University, 2 Cummington St., Boston, Massachusetts 02215, (617) 353-1397, FAX: (617) 358-3269,
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Herberholz J, Issa FA, Edwards DH. Patterns of neural circuit activation and behavior during dominance hierarchy formation in freely behaving crayfish. J Neurosci 2001; 21:2759-67. [PMID: 11306628 PMCID: PMC6762515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
Creation of a dominance hierarchy within a population of animals typically involves a period of agonistic activity in which winning and losing decide relative positions in the hierarchy. Among crayfish, fighting between size-matched animals leads to an abrupt change of behavior as the new subordinate retreats and escapes from the attacks and approaches of the dominant (Issa et al., 1999). We used high-speed videography and electrical recordings of aquarium field potentials to monitor the release of aggressive and defensive behavior, including the activation of neural circuits for four different tail-flip behaviors. We found that the sequence of tail-flip circuit excitation traced the development of their dominance hierarchy. Offensive tail flipping, attacks, and approaches by both animals were followed by a sharp rise in the frequency of nongiant and medial giant escape tail flips and a fall in the frequency of offensive tail flips of the new subordinate. These changes suggest that sudden, coordinated changes in the excitability of a set of neural circuits in one animal produce the changes in behavior that mark its transition to subordinate status.
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Affiliation(s)
- J Herberholz
- Department of Biology, Georgia State University, Atlanta, Georgia 30302-4010, USA
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Edagawa Y, Saito H, Abe K. Endogenous serotonin contributes to a developmental decrease in long-term potentiation in the rat visual cortex. J Neurosci 2001; 21:1532-7. [PMID: 11222643 PMCID: PMC6762958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
The primary visual cortex shows synaptic plasticity during a postnatal "critical period," and its plasticity declines with development. Indeed, we found a developmental decrease in the induction of long-term potentiation (LTP) in the rat visual cortex. In visual cortex slices obtained from 2- to 3-week-old rats, tetanic stimulation (100 Hz for 1 sec, twice at an interval of 30 sec) of the white matter reproducibly induced LTP of field potentials in layer II/III. However, in slices from 5-week-old rats, the same tetanic stimulation failed to induce LTP. We hypothesized that endogenous serotonin (5-HT) is responsible for the developmental decrease in visual cortex LTP, because the induction of visual cortex LTP was suppressed by the addition of exogenous 5-HT (10 microm) and because the amount of 5-HT in the visual cortex increased during development. To test this hypothesis, we investigated the effect of methysergide, a 5-HT receptor antagonist, on the induction of visual cortex LTP. When visual cortex slices from 5-week-old rats were perfused with 50 microm methysergide, tetanic stimulation of the white matter induced robust LTP in layer II/III. Furthermore, serotonergic neurons were lesioned by intracerebroventricular injection of 5,7-dihydroxytryptamine (5,7-DHT). LTP was induced in visual cortex slices from 5,7-DHT-treated, 5-week-old rats. These results suggest that the induction of visual cortex LTP in 5-week-old rats is suppressed by endogenous 5-HT. 5-HT may be a factor that determines a critical period for synaptic plasticity in the rat visual cortex.
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Affiliation(s)
- Y Edagawa
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan
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Varela JA, Sen K, Gibson J, Fost J, Abbott LF, Nelson SB. A quantitative description of short-term plasticity at excitatory synapses in layer 2/3 of rat primary visual cortex. J Neurosci 1997; 17:7926-40. [PMID: 9315911 PMCID: PMC6793910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/1997] [Revised: 07/22/1997] [Accepted: 07/24/1997] [Indexed: 02/05/2023] Open
Abstract
Cortical synapses exhibit several forms of short-term plasticity, but the contribution of this plasticity to visual response dynamics is unknown. In part, this is because the simple patterns of stimulation used to probe plasticity in vitro do not correspond to patterns of activity that occur in vivo. We have developed a method of quantitatively characterizing short-term plasticity at cortical synapses that permits prediction of responses to arbitrary patterns of stimulation. Synaptic responses were recorded intracellularly as EPSCs and extracellularly as local field potentials in layer 2/3 of rat primary visual cortical slices during stimulation of layer 4 with trains of electrical stimuli containing random mixtures of frequencies. Responses exhibited complex dynamics that were well described by a simple three-component model consisting of facilitation and two forms of depression, a stronger form that decayed exponentially with a time constant of several hundred milliseconds and a weaker, but more persistent, form that decayed with a time constant of several seconds. Parameters obtained from fits to one train were used to predict accurately responses to other random and constant frequency trains. Control experiments revealed that depression was not caused by a decrease in the effectiveness of extracellular stimulation or by a buildup of inhibition. Pharmacological manipulations of transmitter release and postsynaptic sensitivity suggested that both forms of depression are mediated presynaptically. These results indicate that firing evoked by visual stimuli is likely to cause significant depression at cortical synapses. Hence synaptic depression may be an important determinant of the temporal features of visual cortical responses.
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Affiliation(s)
- J A Varela
- Department of Biology and Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02254, USA
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Kandel A, Buzsáki G. Cellular-synaptic generation of sleep spindles, spike-and-wave discharges, and evoked thalamocortical responses in the neocortex of the rat. J Neurosci 1997; 17:6783-97. [PMID: 9254689 PMCID: PMC6573130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Thalamocortical neuronal oscillations underlie various field potentials that are expressed in the neocortex, including sleep spindles and high voltage spike-and-wave patterns (HVSs). The mechanism of extracellular current generation in the neocortex was studied in the anesthetized and awake rat. Field potentials and unit activity were recorded simultaneously along trajectories perpendicular to the cortical layers at spatial intervals of 100 microm by multiple-site recording silicon probes. Current source density (CSD) analysis revealed that the spatial positions of sinks in layers IV, V-VI, and II-III and of the accompanying sources were similar during sleep spindles, HVSs, and thalamic-evoked responses, although their relative strengths and timings differed. The magnitude and relative timing of the multiple pairs of sinks and sources determined the amplitude variability of HVSs and sleep spindles. The presence of temporally shifted dipoles was also supported by the time distribution of unit discharges in different layers. Putative interneurons discharged with repetitive bursts of 300-500 Hz. The spike component of HVSs was associated with fast field oscillations (400-600 Hz "ripples"). Discharges of pyramidal cells were phase-locked to the ripples. These findings indicate that the major extracellular currents underlying sleep spindles, HVSs, and evoked responses result from activation of intracortical circuitries. We hypothesize that the fast field ripples reflect summed IPSPs in pyramidal cells resulting from the high frequency barrage of interneurons.
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Affiliation(s)
- A Kandel
- Center for Molecular and Behavioral Neuroscience, Rutgers, The State University of New Jersey, Newark, New Jersey 07102, USA
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Southan AP, Owen DG. The contrasting effects of dendrotoxins and other potassium channel blockers in the CA1 and dentate gyrus regions of rat hippocampal slices. Br J Pharmacol 1997; 122:335-43. [PMID: 9313944 PMCID: PMC1564942 DOI: 10.1038/sj.bjp.0701392] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. The effects of potassium channel blocking compounds on synaptic transmission in the CA1 and dentate gyrus regions of the rat hippocampus were examined by means of simultaneous field potential recording techniques in brain slices. 2. 4-Aminopyridine (4-AP) enhanced the excitatory postsynaptic potential (e.p.s.p.) and induced multiple population spike responses in both regions. EC50 values were 6.7 microM in the CAI (n = 5) and 161.7 microM (n = 5) in the dentate gyrus. 3. Tetraethylammonium (TEA) increased the amplitude and induced broadening of the population spike in both regions. In the dentate gyrus (n = 5) a single slow spike response was introduced (EC50 12.8 mM) and in the CA1 region (n = 5) the response was transformed into two wide spikes (EC50 2.6 mM). 4. In the CA1 region all of the dendrotoxins (toxin I, toxin K, alpha-Dtx and delta-Dtx) induced multiple population spikes and enlarged e.p.s.p. responses. Potentials recorded simultaneously in the dentate gyrus exhibited comparatively minor enhancements. The EC50 value for toxin 1 in the CA1 was calculated to be 237 nM (n = 4). Estimated EC50 values were obtained for alpha-Dtx (1.1 microM, n = 3), toxin K (411 nM, n = 4) and delta-Dtx (176 nM, n = 3). 5. In the presence of toxin 1, DL-2-amino-5-phosphonovaleric acid (APV) induced slight reduction of the late e.p.s.p. phase (n = 3). 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX) abolished all population spikes leaving a late slow positive waveform (n = 3). Co-application of APV and CNQX abolished all postsynaptic responses. 6. Charybdotoxin (CbTx) was significantly less potent than the dendrotoxins and had mixed actions in the CA1 region (n = 3). Again the dentate gyrus exhibited reduced sensitivity (n = 3). 7. In the presence of mast cell degranulating peptide (MCDP), enhancement of the CA1 field potential response (n = 5) was greater than that observed in the dentate gyrus (n = 5). 8. The results show that some potassium channel modulators can profoundly enhance CA1 region synaptic responses in the absence of notable changes in dentate gyrus excitability. Selective enhancement of defined synaptic pathways by potassium channel modulators may prove to have considerable therapeutic potential.
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Affiliation(s)
- A P Southan
- Wyeth Research (UK) Ltd, Maidenhead, Berkshire
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Grassi S, Pettorossi VE, Zampolini M. Low-frequency stimulation cancels the high-frequency-induced long-lasting effects in the rat medial vestibular nuclei. J Neurosci 1996; 16:3373-80. [PMID: 8627373 PMCID: PMC6579131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In rat brainstem slices, we investigated the effects of low-frequency stimulation (LFS) of the primary vestibular afferents on the amplitude of the field potentials evoked in the medial vestibular nuclei (MVN). LFS induced long-term effects, the sign of which depended on whether the vestibular neurons were previously conditioned by HFS. In unconditioned slices, LFS evoked modifications of the responses that were similar to those observed after HFS but had a smaller extension. In fact, LFS caused long-lasting potentiation of the N1 wave in the MVN ventral portion (Vp) and long-lasting depression of the N2 wave in the MVN dorsal portion (Dp), whereas it provoked small and variable effects on the N1 wave. By contrast, when the synaptic transmission was already conditioned, LFS influenced the synaptic responses oppositely, reducing or annulling the HFS long-term effects. This phenomenon was specifically induced by LFS, because HFS was not able to cause it. The involvement of NMDA receptors in mediating the LFS long-term effects was supported by the fact that AP-5 prevented their induction. In addition, the annulment of HFS long-term effects by LFS was also demonstrated by the shift in the latency of the evoked unitary potentials after LFS. In conclusion, we suggest that the reduction of the previously induced conditioning could represent a cancellation mechanism, useful to quickly adapt the vestibular system to continuous different needs and to avoid saturation.
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Affiliation(s)
- S Grassi
- Institute of Human Physiology, University of Perugia, Italy
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