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Brain Topography

, Volume 30, Issue 1, pp 60–76 | Cite as

Identification of Interictal Epileptic Networks from Dense-EEG

  • Mahmoud Hassan
  • Isabelle Merlet
  • Ahmad Mheich
  • Aya Kabbara
  • Arnaud Biraben
  • Anca Nica
  • Fabrice Wendling
Original Paper

Abstract

Epilepsy is a network disease. The epileptic network usually involves spatially distributed brain regions. In this context, noninvasive M/EEG source connectivity is an emerging technique to identify functional brain networks at cortical level from noninvasive recordings. In this paper, we analyze the effect of the two key factors involved in EEG source connectivity processing: (i) the algorithm used in the solution of the EEG inverse problem and (ii) the method used in the estimation of the functional connectivity. We evaluate four inverse solutions algorithms (dSPM, wMNE, sLORETA and cMEM) and four connectivity measures (r 2, h 2, PLV, and MI) on data simulated from a combined biophysical/physiological model to generate realistic interictal epileptic spikes reflected in scalp EEG. We use a new network-based similarity index to compare between the network identified by each of the inverse/connectivity combination and the original network generated in the model. The method will be also applied on real data recorded from one epileptic patient who underwent a full presurgical evaluation for drug-resistant focal epilepsy. In simulated data, results revealed that the selection of the inverse/connectivity combination has a significant impact on the identified networks. Results suggested that nonlinear methods (nonlinear correlation coefficient, phase synchronization and mutual information) for measuring the connectivity are more efficient than the linear one (the cross correlation coefficient). The wMNE inverse solution showed higher performance than dSPM, cMEM and sLORETA. In real data, the combination (wMNE/PLV) led to a very good matching between the interictal epileptic network identified from noninvasive EEG recordings and the network obtained from connectivity analysis of intracerebral EEG recordings. These results suggest that source connectivity method, when appropriately configured, is able to extract highly relevant diagnostic information about networks involved in interictal epileptic spikes from non-invasive dense-EEG data.

Keywords

Epilepsy Dense-EEG source connectivity Epileptic networks 

Notes

Acknowledgments

This work has received a French government support granted to the CominLabs excellence laboratory and managed by the National Research Agency in the “Investing for the Future” program under reference ANR-10-LABX-07-01. It was also financed by the Rennes University Hospital (COREC Project named conneXion, 2012-14).

Supplementary material

10548_2016_517_MOESM1_ESM.docx (74 kb)
Supplementary material 1 (DOCX 74 kb)

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Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  1. 1.INSERM, U1099RennesFrance
  2. 2.LTSIUniversité de Rennes 1RennesFrance
  3. 3.Neurology DepartmentCHURennesFrance
  4. 4.AZM Center-EDSTLebanese UniversityTripoliLebanon

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