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ORIGINAL RESEARCH article

Front. Neuroimaging
Sec. Brain Imaging Methods
Volume 3 - 2024 | doi: 10.3389/fnimg.2024.1423770

Probing hippocampal stimulation in experimental temporal lobe epilepsy with functional MRI

Provisionally accepted
Niels Schwaderlapp Niels Schwaderlapp 1*Enya Paschen Enya Paschen 2Pierre LeVan Pierre LeVan 3Dominik Von Elverfeldt Dominik Von Elverfeldt 1Carola A. Haas Carola A. Haas 2
  • 1 Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Freiburg, Germany
  • 2 Experimental Epilepsy Research, Department of Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Freiburg, Germany
  • 3 Departments of Radiology and Paediatrics, Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada, Calgary, Canada

The final, formatted version of the article will be published soon.

    Electrical neurostimulation is currently used to manage epilepsy, but the most effective approach for minimizing seizure occurrence is uncertain. While functional MRI (fMRI) can reveal which brain areas are affected by stimulation, simultaneous deep brain stimulation (DBS)-fMRI examinations in patients are rare and the possibility to investigate multiple stimulation protocols is limited. In this study, we utilized the intrahippocampal kainate mouse model of mesial temporal lobe epilepsy (mTLE) to systematically examine the brain-wide responses to electrical stimulation using fMRI. We compared fMRI responses of saline-injected controls and epileptic mice during stimulation in the septal hippocampus (HC) at 10 Hz and demonstrated the effects of different stimulation amplitudes (80-230 µA) and frequencies (1-100 Hz) in epileptic mice. Motivated by recent studies exploring 1 Hz stimulation to prevent epileptic seizures, we furthermore investigated the effect of prolonged 1 Hz stimulation with fMRI. Compared to sham controls, epileptic mice showed less propagation to the contralateral HC, but significantly stronger responses in the ipsilateral HC and a wider spread to the entorhinal cortex and septal region. Varying the stimulation amplitude had little effect on the resulting activation patterns, whereas the stimulation frequency represented the key parameter and determined whether the induced activation remained local or spread from the hippocampal formation into cortical areas. Prolonged stimulation of epileptic mice at 1 Hz caused a slight reduction in local excitability. In this way, our study contributes to a better understanding of these stimulation paradigms.

    Keywords: DBS, fMRI, Epilepsy, kainate mouse model, TLE, Hippocampus

    Received: 26 Apr 2024; Accepted: 29 Jul 2024.

    Copyright: © 2024 Schwaderlapp, Paschen, LeVan, Von Elverfeldt and Haas. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Niels Schwaderlapp, Division of Medical Physics, Department of Diagnostic and Interventional Radiology, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Freiburg, Germany

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