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Bello ST, Xu S, Li X, Ren J, Jendrichovsky P, Jiang F, Xiao Z, Wan X, Chen X, He J. Visually or auditorily induced seizures involve the activation of nonhippocampal brain areas and hippocampal removal does not alleviate seizures in a mouse model of temporal lobe epilepsy. Epilepsia 2024; 65:218-237. [PMID: 38032046 DOI: 10.1111/epi.17816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 10/28/2023] [Accepted: 10/31/2023] [Indexed: 12/01/2023]
Abstract
OBJECTIVE Several studies have attributed epileptic activities in temporal lobe epilepsy (TLE) to the hippocampus; however, the participation of nonhippocampal neuronal networks in the development of TLE is often neglected. Here, we sought to understand how these nonhippocampal networks are involved in the pathology that is associated with TLE disease. METHODS A kainic acid (KA) model of temporal lobe epilepsy was induced by injecting KA into dorsal hippocampus of C57BL/6J mice. Network activation after spontaneous seizure was assessed using c-Fos expression. Protocols to induce seizure using visual or auditory stimulation were developed, and seizure onset zone (SOZ) and frequency of epileptic spikes were evaluated using electrophysiology. The hippocampus was removed to assess seizure recurrence in the absence of hippocampus. RESULTS Our results showed that cortical and hippocampal epileptic networks are activated during spontaneous seizures. Perturbation of these networks using visual or auditory stimulation readily precipitates seizures in TLE mice; the frequency of the light-induced or noise-induced seizures depends on the induction modality adopted during the induction period. Localization of SOZ revealed the existence of cortical and hippocampal SOZ in light-induced and noise-induced seizures, and the development of local and remote epileptic spikes in TLE occurs during the early stage of the disease. Importantly, we further discovered that removal of the hippocampi does not stop seizure activities in TLE mice, revealing that seizures in TLE mice can occur independent of the hippocampus. SIGNIFICANCE This study has shown that the network pathology that evolves in TLE is not localized to the hippocampus; rather, remote brain areas are also recruited. The occurrence of light-induced or noise-induced seizures and epileptic discharges in epileptic mice is a consequence of the activation of nonhippocampal brain areas. This work therefore demonstrates the fundamental role of nonhippocampal epileptic networks in generating epileptic activities with or without the hippocampus in TLE disease.
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Affiliation(s)
- Stephen Temitayo Bello
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biomedical Science, City University of Hong Kong, Kowloon, Hong Kong
- Center for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, New Territories, Hong Kong
| | - Shenghui Xu
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biomedical Science, City University of Hong Kong, Kowloon, Hong Kong
| | - Xiao Li
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Junming Ren
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Peter Jendrichovsky
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biomedical Science, City University of Hong Kong, Kowloon, Hong Kong
| | - Feixu Jiang
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
- Center for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, New Territories, Hong Kong
| | - Zhoujian Xiao
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Xiaoxiao Wan
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Xi Chen
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
| | - Jufang He
- Department of Neuroscience, City University of Hong Kong, Kowloon, Hong Kong
- Department of Biomedical Science, City University of Hong Kong, Kowloon, Hong Kong
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Rodgers G, Bikis C, Janz P, Tanner C, Schulz G, Thalmann P, Haas CA, Müller B. 3D X-ray Histology for the Investigation of Temporal Lobe Epilepsy in a Mouse Model. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:1730-1745. [PMID: 37584515 DOI: 10.1093/micmic/ozad082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/29/2023] [Accepted: 07/28/2023] [Indexed: 08/17/2023]
Abstract
The most common form of epilepsy among adults is mesial temporal lobe epilepsy (mTLE), with seizures often originating in the hippocampus due to abnormal electrical activity. The gold standard for the histopathological analysis of mTLE is histology, which is a two-dimensional technique. To fill this gap, we propose complementary three-dimensional (3D) X-ray histology. Herein, we used synchrotron radiation-based phase-contrast microtomography with 1.6 μm-wide voxels for the post mortem visualization of tissue microstructure in an intrahippocampal-kainate mouse model for mTLE. We demonstrated that the 3D X-ray histology of unstained, unsectioned, paraffin-embedded brain hemispheres can identify hippocampal sclerosis through the loss of pyramidal neurons in the first and third regions of the Cornu ammonis as well as granule cell dispersion within the dentate gyrus. Morphology and density changes during epileptogenesis were quantified by segmentations from a deep convolutional neural network. Compared to control mice, the total dentate gyrus volume doubled and the granular layer volume quadrupled 21 days after injecting kainate. Subsequent sectioning of the same mouse brains allowed for benchmarking 3D X-ray histology against well-established histochemical and immunofluorescence stainings. Thus, 3D X-ray histology is a complementary neuroimaging tool to unlock the third dimension for the cellular-resolution histopathological analysis of mTLE.
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Affiliation(s)
- Griffin Rodgers
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
- Biomaterials Science Center, Department of Clinical Research, University Hospital Basel, 4031 Basel, Switzerland
| | - Christos Bikis
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
- Integrierte Psychiatrie Winterthur-Zürcher Unterland, 8408 Winterthur, Switzerland
| | - Philipp Janz
- Faculty of Medicine, Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, 79106 Freiburg, Germany
- Faculty of Biology, University of Freiburg, 79106 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, 79106 Freiburg, Germany
| | - Christine Tanner
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
- Biomaterials Science Center, Department of Clinical Research, University Hospital Basel, 4031 Basel, Switzerland
| | - Georg Schulz
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
- Biomaterials Science Center, Department of Clinical Research, University Hospital Basel, 4031 Basel, Switzerland
- Core Facility Micro- and Nanotomography, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
| | - Peter Thalmann
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
| | - Carola A Haas
- Faculty of Medicine, Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, 79106 Freiburg, Germany
- BrainLinks-BrainTools Center, University of Freiburg, 79106 Freiburg, Germany
- Center of Basics in NeuroModulation, Faculty of Medicine, University of Freiburg, 79114 Freiburg, Germany
| | - Bert Müller
- Biomaterials Science Center, Department of Biomedical Engineering, University of Basel, 4123 Allschwil, Switzerland
- Biomaterials Science Center, Department of Clinical Research, University Hospital Basel, 4031 Basel, Switzerland
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Sala-Padro J, Gifreu-Fraixino A, Miró J, Rodriguez-Fornells A, Rico I, Plans G, Santurino M, Falip M, Càmara E. Verbal Learning and Longitudinal Hippocampal Network Connectivity in Temporal Lobe Epilepsy Surgery. Front Neurol 2022; 13:854313. [PMID: 35800085 PMCID: PMC9253296 DOI: 10.3389/fneur.2022.854313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/23/2022] [Indexed: 11/24/2022] Open
Abstract
Introduction Learning new verbal information can be impaired in 20–40% of patients after mesial temporal lobe resection. In recent years, understanding epilepsy as a brain network disease, and investigating the relationship between large-scale resting networks and cognition has led to several advances. Aligned studies suggest that it is the integrity of the hippocampal connectivity with these large-scale networks what is relevant for cognition, with evidence showing a functional and structural heterogeneity along the long axis hippocampus bilaterally. Objective Our aim is to examine whether pre-operative resting-state connectivity along the long hippocampal axis is associated with verbal learning decline after anterior temporal lobe resection. Methods Thirty-one patients with epilepsy who underwent an anterior temporal lobe resection were pre-surgically scanned at 3-tesla, and pre/post-surgery evaluated for learning deficits using the Rey Auditory Verbal Learning Task (RAVLT). Eighteen controls matched by age, gender and handedness were also scanned and evaluated with the RAVLT. We studied the functional connectivity along the (anterior/posterior) long axis hippocampal subregions and resting-state functionally-defined brain networks involved in learning [executive (EXE), dorsal attention (DAN) and default-mode (DMN) networks]. Functional connectivity differences between the two groups of patients (learning intact or with learning decline) and controls were investigated with MANOVA and discriminant analysis. Results There were significant differences in the pattern of hippocampal connectivity among the groups. Regarding the anterior connectivity hippocampal pattern, our data showed an increase of connectivity in the pathological side with the DAN (p = 0.011) and the EXE (p = 0.008) when comparing learning-decline vs. learning-intact patients. Moreover, the non-pathological side showed an increase in the anterior connectivity pattern with the DAN (p = 0.027) between learning-decline vs. learning-intact patients. In contrast, the posterior hippocampus showed a reduction of connectivity in the learning-decline patients with the DMN, both in the pathological (p = 0.004) and the non-pathological sides (p = 0.036). Finally, the discriminant analysis based on the pre-operative connectivity pattern significantly differentiated the learning-decline patients from the other groups (p = 0.019). Conclusion Our findings reveal bilateral connectivity disruptions along the longitudinal axis of the hippocampi with resting-state networks, which could be key to identify those patients at risk of verbal learning decline after epilepsy surgery.
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Affiliation(s)
- Jacint Sala-Padro
- Epilepsy Unit, Hospital de Bellvitge, Barcelona, Spain
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | | | - Júlia Miró
- Epilepsy Unit, Hospital de Bellvitge, Barcelona, Spain
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
| | - Antoni Rodriguez-Fornells
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
- Department of Cognition, Development and Educational Science, L'Hospitalet de Llobregat, University of Barcelona, Barcelona, Spain
- Catalan Institution for Research and Advanced Studies, ICREA, Barcelona, Spain
| | | | - Gerard Plans
- Epilepsy Unit, Hospital de Bellvitge, Barcelona, Spain
| | | | - Mercè Falip
- Epilepsy Unit, Hospital de Bellvitge, Barcelona, Spain
| | - Estela Càmara
- Cognition and Brain Plasticity Group, Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain
- Department of Cognition, Development and Educational Science, L'Hospitalet de Llobregat, University of Barcelona, Barcelona, Spain
- *Correspondence: Estela Càmara
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Chau Loo Kung G, Chiu A, Davey Z, Mouchawar N, Carlson M, Moein Taghavi H, Martin D, Graber K, Razavi B, McNab J, Zeineh M. High-resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy. Epilepsia 2022; 63:2301-2311. [PMID: 35751514 DOI: 10.1111/epi.17330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/10/2022] [Accepted: 06/13/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE We explore the possibility of using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to discern microstructural abnormalities in the hippocampus indicative of mesial temporal sclerosis (MTS) at the subfield level. METHODS We analyzed data from 57 patients with refractory epilepsy who previously underwent 3.0-T magnetic resonance imaging (MRI) including DTI as a standard part of presurgical workup. We collected information about each subject's seizure semiology, conventional electroencephalography (EEG), high-density EEG, positron emission tomography reports, surgical outcome, and available histopathological findings to assign a final diagnostic category. We also reviewed the radiology MRI report to determine the radiographic category. DTI- and NODDI-based metrics were obtained in the hippocampal subfields. RESULTS By examining diffusion characteristics among subfields in the final diagnostic categories, we found lower orientation dispersion indices and elevated axial diffusivity in the dentate gyrus in MTS compared to no MTS. By similarly examining among subfields in the different radiographic categories, we found all diffusion metrics were abnormal in the dentate gyrus and CA1. We finally examined whether diffusion imaging would better inform a radiographic diagnosis with respect to the final diagnosis, and found that dentate diffusivity suggested subtle changes that may help confirm a positive radiologic diagnosis. SIGNIFICANCE The results suggest that diffusion metric analysis at the subfield level, especially in dentate gyrus and CA1, maybe useful for clinical confirmation of MTS.
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Affiliation(s)
- Gustavo Chau Loo Kung
- Bioengineering Department, Stanford University, Stanford, California, USA.,Radiology Department, Stanford University, Stanford, California, USA
| | - Andrew Chiu
- Radiology Department, Stanford University, Stanford, California, USA
| | - Zach Davey
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Nicole Mouchawar
- Radiology Department, Stanford University, Stanford, California, USA
| | - Mackenzie Carlson
- Bioengineering Department, Stanford University, Stanford, California, USA.,Radiology Department, Stanford University, Stanford, California, USA
| | | | | | - Kevin Graber
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Babak Razavi
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Jennifer McNab
- Radiology Department, Stanford University, Stanford, California, USA
| | - Michael Zeineh
- Radiology Department, Stanford University, Stanford, California, USA
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