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Tabatabaee S, Bahrami F, Janahmadi M. The Critical Modulatory Role of Spiny Stellate Cells in Seizure Onset Based on Dynamic Analysis of a Neural Mass Model. Front Neurosci 2022; 15:743720. [PMID: 35002598 PMCID: PMC8739215 DOI: 10.3389/fnins.2021.743720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
Growing evidence suggests that excitatory neurons in the brain play a significant role in seizure generation. Nonetheless, spiny stellate cells are cortical excitatory non-pyramidal neurons in the brain, whose basic role in seizure occurrence is not well understood. In the present research, we study the critical role of spiny stellate cells or the excitatory interneurons (EI), for the first time, in epileptic seizure generation using an extended neural mass model inspired by a thalamocortical model originally introduced by another research group. Applying bifurcation analysis on this modified model, we investigated the rich dynamics corresponding to the epileptic seizure onset and transition between interictal and ictal states caused by EI connectivity to other cell types. Our results indicate that the transition between interictal and ictal states (preictal signal) corresponds to a supercritical Hopf bifurcation, and thus, the extended model suggests that before seizure onset, the amplitude and frequency of neural activities gradually increase. Moreover, we showed that (1) the altered function of GABAergic and glutamatergic receptors of EI can cause seizure, and (2) the pathway between the thalamic relay nucleus and EI facilitates the transition from interictal to ictal activity by decreasing the preictal period. Thereafter, we considered both sensory and cortical periodic inputs to study model responses to various harmonic stimulations. Bifurcation analysis of the model, in this case, suggests that the initial state of the model might be the main cause for the transition between interictal and ictal states as the stimulus frequency changes. The extended thalamocortical model shows also that the amplitude jump phenomenon and non-linear resonance behavior result from the preictal state of the modified model. These results can be considered as a step forward to a deeper understanding of the mechanisms underlying the transition from normal activities to epileptic activities.
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Affiliation(s)
- Saba Tabatabaee
- Human Motor Control and Computational Neuroscience Laboratory, School of Electrical and Computer Engineering (ECE), College of Engineering, University of Tehran, Tehran, Iran
| | - Fariba Bahrami
- Human Motor Control and Computational Neuroscience Laboratory, School of Electrical and Computer Engineering (ECE), College of Engineering, University of Tehran, Tehran, Iran
| | - Mahyar Janahmadi
- Department of Physiology, Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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Wenzel M, Hamm JP, Peterka DS, Yuste R. Acute Focal Seizures Start As Local Synchronizations of Neuronal Ensembles. J Neurosci 2019; 39:8562-8575. [PMID: 31427393 PMCID: PMC6807279 DOI: 10.1523/jneurosci.3176-18.2019] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 07/27/2019] [Accepted: 08/09/2019] [Indexed: 11/21/2022] Open
Abstract
Understanding seizure formation and spread remains a critical goal of epilepsy research. We used fast in vivo two-photon calcium imaging in male mouse neocortex to reconstruct, with single-cell resolution, the dynamics of acute (4-aminopyridine) focal cortical seizures as they originate within a spatially confined seizure initiation site (intrafocal region), and subsequently propagate into neighboring cortical areas (extrafocal region). We find that seizures originate as local neuronal ensembles within the initiation site. This abnormal hyperactivity engages increasingly larger areas in a saltatory fashion until it breaks into neighboring cortex, where it proceeds smoothly and is then detected electrophysiologically (LFP). Interestingly, PV inhibitory interneurons have spatially heterogeneous activity in intrafocal and extrafocal territories, ruling out a simple role of inhibition in seizure formation and spread. We propose a two-step model for the progression of focal seizures, where neuronal ensembles activate first, generating a microseizure, followed by widespread neural activation in a traveling wave through neighboring cortex during macroseizures.SIGNIFICANCE STATEMENT We have used calcium imaging in mouse sensory cortex in vivo to reconstruct the onset of focal seizures elicited by local injection of the chemoconvulsant 4-aminopyridine. We demonstrate at cellular resolution that acute focal seizures originate as increasingly synchronized local neuronal ensembles. Because of its spatial confinement, this process may at first be undetectable even by nearby LFP electrodes. Further, we establish spatial footprints of local neural subtype activity that correspond to consecutive steps of seizure microprogression. Such footprints could facilitate determining the recording location (e.g., inside/outside an epileptogenic focus) in high-resolution studies, even in the absence of a priori knowledge about where exactly a seizure started.
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Affiliation(s)
- Michael Wenzel
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Jordan P Hamm
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Darcy S Peterka
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Rafael Yuste
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, New York 10027
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Yang DP, Robinson PA. Unified analysis of global and focal aspects of absence epilepsy via neural field theory of the corticothalamic system. Phys Rev E 2019; 100:032405. [PMID: 31639915 DOI: 10.1103/physreve.100.032405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Indexed: 06/10/2023]
Abstract
Absence epilepsy is characterized by a sudden paroxysmal loss of consciousness accompanied by oscillatory activity propagating over many brain areas. Although primary generalized absence seizures are supported by the global corticothalamic system, converging experimental evidence supports a focal theory of absence epilepsy. Here a physiology-based corticothalamic model is investigated with spatial heterogeneity due to focal epilepsy to unify global and focal aspects of absence epilepsy. Numeric and analytic calculations are employed to investigate the emergent spatiotemporal dynamics as well as their underlying dynamical mechanisms. They can be categorized into three scenarios: suppressed epilepsy, focal seizures, or generalized seizures, as summarized from a phase diagram vs focal width and characteristic axon range. The corresponding temporal frequencies and spatial extents of cortical waves in generalized seizures and focal seizures agree well with experimental observations of global and focal aspects of absence epilepsy, respectively. The emergence of the spatiotemporal dynamics corresponding to focal seizures provides a biophysical explanation of the temporally higher frequency but spatially more localized cortical waves observed in genetic rat models that display characteristics of human absence epilepsy. Predictions are also presented for further experimental test.
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Affiliation(s)
- Dong-Ping Yang
- School of Physics, University of Sydney, New South Wales 2006, Australia and Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia
| | - P A Robinson
- School of Physics, University of Sydney, New South Wales 2006, Australia and Center for Integrative Brain Function, University of Sydney, New South Wales 2006, Australia
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Wenzel M, Hamm JP, Peterka DS, Yuste R. Reliable and Elastic Propagation of Cortical Seizures In Vivo. Cell Rep 2018; 19:2681-2693. [PMID: 28658617 DOI: 10.1016/j.celrep.2017.05.090] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 05/15/2017] [Accepted: 05/28/2017] [Indexed: 12/27/2022] Open
Abstract
Mapping the fine-scale neural activity that underlies epilepsy is key to identifying potential control targets of this frequently intractable disease. Yet, the detailed in vivo dynamics of seizure progression in cortical microcircuits remain poorly understood. We combine fast (30-Hz) two-photon calcium imaging with local field potential (LFP) recordings to map, cell by cell, the spread of locally induced (4-AP or picrotoxin) seizures in anesthetized and awake mice. Using single-layer and microprism-assisted multilayer imaging in different cortical areas, we uncover reliable recruitment of local neural populations within and across cortical layers, and we find layer-specific temporal delays, suggesting an initial supra-granular invasion followed by deep-layer recruitment during lateral seizure spread. Intriguingly, despite consistent progression pathways, successive seizures show pronounced temporal variability that critically depends on GABAergic inhibition. We propose an epilepsy circuit model resembling an elastic meshwork, wherein ictal progression faithfully follows preexistent pathways but varies flexibly in time, depending on the local inhibitory restraint.
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Affiliation(s)
- Michael Wenzel
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
| | - Jordan P Hamm
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Darcy S Peterka
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Rafael Yuste
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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Gottschalk S, Fehm TF, Deán-Ben XL, Tsytsarev V, Razansky D. Correlation between volumetric oxygenation responses and electrophysiology identifies deep thalamocortical activity during epileptic seizures. NEUROPHOTONICS 2017; 4:011007. [PMID: 27725948 PMCID: PMC5050254 DOI: 10.1117/1.nph.4.1.011007] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 09/13/2016] [Indexed: 05/05/2023]
Abstract
Visualization of whole brain activity during epileptic seizures is essential for both fundamental research into the disease mechanisms and the development of efficient treatment strategies. It has been previously discussed that pathological synchronization originating from cortical areas may reinforce backpropagating signaling from the thalamic neurons, leading to massive seizures through enhancement of high frequency neural activity in the thalamocortical loop. However, the study of deep brain neural activity is challenging with the existing functional neuroimaging methods due to lack of adequate spatiotemporal resolution or otherwise insufficient penetration into subcortical areas. To investigate the role of thalamocortical activity during epileptic seizures, we developed a new functional neuroimaging framework based on spatiotemporal correlation of volumetric optoacoustic hemodynamic responses with the concurrent electroencephalogram recordings and anatomical brain landmarks. The method is shown to be capable of accurate three-dimensional mapping of the onset, spread, and termination of the epileptiform events in a 4-aminopyridine acute model of focal epilepsy. Our study is the first to demonstrate entirely noninvasive real-time visualization of synchronized epileptic foci in the whole mouse brain, including the neocortex and subcortical structures, thus opening new vistas in systematic studies toward the understanding of brain signaling and the origins of neurological disorders.
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Affiliation(s)
- Sven Gottschalk
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Thomas Felix Fehm
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
- Technical University of Munich, Faculty of Medicine, Ismaninger Str. 22, 81675 Munich, Germany
| | - Xose Luís Deán-Ben
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
| | - Vassiliy Tsytsarev
- University of Maryland School of Medicine, Department of Anatomy and Neurobiology, 20 Penn Street, HSF II, Baltimore, Maryland 21201, United States
| | - Daniel Razansky
- Institute for Biological and Medical Imaging (IBMI), Helmholtz Center Munich, Ingolstaedter Landstrasse 1, 85764 Neuherberg, Germany
- Technical University of Munich, Faculty of Medicine, Ismaninger Str. 22, 81675 Munich, Germany
- Address all correspondence to: Daniel Razansky, E-mail:
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Pedersen M, Curwood EK, Vaughan DN, Omidvarnia AH, Jackson GD. Abnormal Brain Areas Common to the Focal Epilepsies: Multivariate Pattern Analysis of fMRI. Brain Connect 2016; 6:208-15. [DOI: 10.1089/brain.2015.0367] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Mangor Pedersen
- The Florey Institute of Neuroscience and Mental Health, Austin Campus, Melbourne, Australia
- The University of Melbourne, Florey Department of Neuroscience and Mental Health, Melbourne, Australia
| | - Evan K. Curwood
- The Florey Institute of Neuroscience and Mental Health, Austin Campus, Melbourne, Australia
| | - David N. Vaughan
- The Florey Institute of Neuroscience and Mental Health, Austin Campus, Melbourne, Australia
- The University of Melbourne, Florey Department of Neuroscience and Mental Health, Melbourne, Australia
- Department of Neurology, Austin Health, Melbourne, Australia
| | - Amir H. Omidvarnia
- The Florey Institute of Neuroscience and Mental Health, Austin Campus, Melbourne, Australia
- The University of Melbourne, Florey Department of Neuroscience and Mental Health, Melbourne, Australia
| | - Graeme D. Jackson
- The Florey Institute of Neuroscience and Mental Health, Austin Campus, Melbourne, Australia
- The University of Melbourne, Florey Department of Neuroscience and Mental Health, Melbourne, Australia
- Department of Neurology, Austin Health, Melbourne, Australia
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Increased segregation of brain networks in focal epilepsy: An fMRI graph theory finding. NEUROIMAGE-CLINICAL 2015; 8:536-42. [PMID: 26110111 PMCID: PMC4477107 DOI: 10.1016/j.nicl.2015.05.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 05/15/2015] [Accepted: 05/19/2015] [Indexed: 11/23/2022]
Abstract
Focal epilepsy is conceived of as activating local areas of the brain as well as engaging regional brain networks. Graph theory represents a powerful quantitative framework for investigation of brain networks. Here we investigate whether functional network changes are present in extratemporal focal epilepsy. Task-free functional magnetic resonance imaging data from 15 subjects with extratemporal epilepsy and 26 age and gender matched healthy controls were used for analysis. Local network properties were calculated using local efficiency, clustering coefficient and modularity metrics. Global network properties were assessed with global efficiency and betweenness centrality metrics. Cost-efficiency of the networks at both local and global levels was evaluated by estimating the physical distance between functionally connected nodes, in addition to the overall numbers of connections in the network. Clustering coefficient, local efficiency and modularity were significantly higher in individuals with focal epilepsy than healthy control subjects, while global efficiency and betweenness centrality were not significantly different between the two groups. Local network properties were also highly efficient, at low cost, in focal epilepsy subjects compared to healthy controls. Our results show that functional networks in focal epilepsy are altered in a way that the nodes of the network are more isolated. We postulate that network regularity, or segregation of the nodes of the networks, may be an adaptation that inhibits the conversion of the interictal state to seizures. It remains possible that this may be part of the epileptogenic process or an effect of medications. Focal epilepsy is a neurological disorder known to affect neural networks. We examine fMRI network changes during rest in extratemporal epilepsy patients. Extratemporal epilepsy subjects show increased (isolated) local network regularity. Network isolation may represent a ‘seizure-protection’ mechanism in focal epilepsy.
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