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Paschen E, Kleis P, Vieira DM, Heining K, Boehler C, Egert U, Häussler U, Haas CA. On-demand low-frequency stimulation for seizure control: efficacy and behavioural implications. Brain 2024; 147:505-520. [PMID: 37675644 DOI: 10.1093/brain/awad299] [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: 03/20/2023] [Revised: 07/24/2023] [Accepted: 08/28/2023] [Indexed: 09/08/2023] Open
Abstract
Mesial temporal lobe epilepsy (MTLE), the most common form of focal epilepsy in adults, is often refractory to medication and associated with hippocampal sclerosis. Deep brain stimulation represents an alternative treatment option for drug-resistant patients who are ineligible for resective brain surgery. In clinical practice, closed-loop stimulation at high frequencies is applied to interrupt ongoing seizures, yet has (i) a high incidence of false detections; (ii) the drawback of delayed seizure-suppressive intervention; and (iii) limited success in sclerotic tissue. As an alternative, low-frequency stimulation (LFS) has been explored recently in patients with focal epilepsies. In preclinical epilepsy models, hippocampal LFS successfully prevented seizures when applied continuously. Since it would be advantageous to reduce the stimulation load, we developed a protocol for on-demand LFS. Given the importance of the hippocampus for navigation and memory, we investigated potential consequences of LFS on hippocampal function. To this end, we used the intrahippocampal kainate mouse model, which recapitulates the key features of MTLE, including spontaneous seizure activity and hippocampal sclerosis. Specifically, our online detection algorithm monitored epileptiform activity in hippocampal local field potential recordings and identified short epileptiform bursts preceding focal seizure clusters, triggering hippocampal LFS to stabilize the network state. To probe behavioural performance, we tested the acute influence of LFS on anxiety-like behaviour in the light-dark box test, spatial and non-spatial memory in the object location memory and novel object recognition test, as well as spatial navigation and long-term memory in the Barnes maze. On-demand LFS was almost as effective as continuous LFS in preventing focal seizure clusters but with a significantly lower stimulation load. When we compared the behavioural performance of chronically epileptic mice to healthy controls, we found that both groups were equally mobile, but epileptic mice displayed an increased anxiety level, altered spatial learning strategy and impaired memory performance. Most importantly, with the application of hippocampal LFS before behavioural training and test sessions, we could rule out deleterious effects on cognition and even show an alleviation of deficits in long-term memory recall in chronically epileptic mice. Taken together, our findings may provide a promising alternative to current therapies, overcoming some of their major limitations, and inspire further investigation of LFS for seizure control in focal epilepsy syndromes.
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Affiliation(s)
- Enya Paschen
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Piret Kleis
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- Faculty of Biology, University of Freiburg, Freiburg 79104, Germany
| | - Diego M Vieira
- Biomicrotechnology, Department of Microsystems Engineering-IMTEK, Faculty of Engineering, University of Freiburg, Freiburg 79108, Germany
| | - Katharina Heining
- Department of Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
| | - Christian Boehler
- Department of Microsystems Engineering (IMTEK), Bioelectronic Microtechnology (BEMT), University of Freiburg, Freiburg 79108, Germany
| | - Ulrich Egert
- Biomicrotechnology, Department of Microsystems Engineering-IMTEK, Faculty of Engineering, University of Freiburg, Freiburg 79108, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
| | - Ute Häussler
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
| | - Carola A Haas
- Experimental Epilepsy Research, Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, Freiburg 79106, Germany
- BrainLinks-BrainTools Center, University of Freiburg, Freiburg 79110, Germany
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Masala N, Mittag M, Giovannetti EA, O'Neil DA, Distler F, Rupprecht P, Helmchen F, Yuste R, Fuhrmann M, Beck H, Wenzel M, Kelly T. Aberrant hippocampal Ca 2+ micro-waves following synapsin-dependent adeno-associated viral expression of Ca 2+ indicators. bioRxiv 2024:2023.11.08.566169. [PMID: 37986838 PMCID: PMC10659308 DOI: 10.1101/2023.11.08.566169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Genetically encoded calcium indicators (GECIs) such as GCaMP are invaluable tools in neuroscience to monitor neuronal activity using optical imaging. The viral transduction of GECIs is commonly used to target expression to specific brain regions, can be conveniently used with any mouse strain of interest without the need for prior crossing with a GECI mouse line and avoids potential hazards due to the chronic expression of GECIs during development. A key requirement for monitoring neuronal activity with an indicator is that the indicator itself minimally affects activity. Here, using common adeno-associated viral (AAV) transduction procedures, we describe spatially confined aberrant Ca2+ micro-waves slowly travelling through the hippocampus following expression of GCaMP6, GCaMP7 or R-CaMP1.07 driven by the synapsin promoter with AAV-dependent gene transfer, in a titre-dependent fashion. Ca2+ micro-waves developed in hippocampal CA1 and CA3, but not dentate gyrus (DG) nor neocortex, were typically first observed at 4 weeks after viral transduction, and persisted up to at least 8 weeks. The phenomenon was robust, observed across laboratories with various experimenters and setups. Our results indicate that aberrant hippocampal Ca2+ micro-waves depend on the promoter and viral titre of the GECI, density of expression as well as the targeted brain region. We used an alternative viral transduction method of GCaMP which avoids this artifact. The results show that commonly used Ca2+-indicator AAV transduction procedures can produce artefactual Ca2+ responses. Our aim is to raise awareness in the field of these artefactual transduction-induced Ca2+ micro-waves and we provide a potential solution.
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Affiliation(s)
- Nicola Masala
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR), Bonn, Germany
- University Hospital Bonn
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
| | - Manuel Mittag
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | | | - Darik A O'Neil
- NeuroTechnology Center, Columbia University, New York, NY, USA
| | - Fabian Distler
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR), Bonn, Germany
- University Hospital Bonn
| | - Peter Rupprecht
- Brain Research Institute, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
| | - Fritjof Helmchen
- Brain Research Institute, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich, Zurich, Switzerland
| | - Rafael Yuste
- NeuroTechnology Center, Columbia University, New York, NY, USA
| | - Martin Fuhrmann
- Neuroimmunology and Imaging Group, German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Heinz Beck
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR), Bonn, Germany
- University Hospital Bonn
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Michael Wenzel
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR), Bonn, Germany
- University Hospital Bonn
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
| | - Tony Kelly
- University of Bonn, Faculty of Medicine, Institute for Experimental Epileptology and Cognition Research (IEECR), Bonn, Germany
- University Hospital Bonn
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Stöber TM, Batulin D, Triesch J, Narayanan R, Jedlicka P. Degeneracy in epilepsy: multiple routes to hyperexcitable brain circuits and their repair. Commun Biol 2023; 6:479. [PMID: 37137938 PMCID: PMC10156698 DOI: 10.1038/s42003-023-04823-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [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: 05/24/2022] [Accepted: 04/06/2023] [Indexed: 05/05/2023] Open
Abstract
Due to its complex and multifaceted nature, developing effective treatments for epilepsy is still a major challenge. To deal with this complexity we introduce the concept of degeneracy to the field of epilepsy research: the ability of disparate elements to cause an analogous function or malfunction. Here, we review examples of epilepsy-related degeneracy at multiple levels of brain organisation, ranging from the cellular to the network and systems level. Based on these insights, we outline new multiscale and population modelling approaches to disentangle the complex web of interactions underlying epilepsy and to design personalised multitarget therapies.
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Affiliation(s)
- Tristan Manfred Stöber
- Frankfurt Institute for Advanced Studies, 60438, Frankfurt am Main, Germany
- Institute for Neural Computation, Faculty of Computer Science, Ruhr University Bochum, 44801, Bochum, Germany
- Epilepsy Center Frankfurt Rhine-Main, Department of Neurology, Goethe University, 60590, Frankfurt, Germany
| | - Danylo Batulin
- Frankfurt Institute for Advanced Studies, 60438, Frankfurt am Main, Germany
- CePTER - Center for Personalized Translational Epilepsy Research, Goethe University, 60590, Frankfurt, Germany
- Faculty of Computer Science and Mathematics, Goethe University, 60486, Frankfurt, Germany
| | - Jochen Triesch
- Frankfurt Institute for Advanced Studies, 60438, Frankfurt am Main, Germany
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Peter Jedlicka
- ICAR3R - Interdisciplinary Centre for 3Rs in Animal Research, Faculty of Medicine, Justus Liebig University Giessen, 35390, Giessen, Germany.
- Institute of Clinical Neuroanatomy, Neuroscience Center, Goethe University, 60590, Frankfurt am Main, Germany.
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