Neuroinformatics

, Volume 11, Issue 2, pp 159–173

A Systems-Level Approach to Human Epileptic Seizures

  • Christian Rummel
  • Marc Goodfellow
  • Heidemarie Gast
  • Martinus Hauf
  • Frédérique Amor
  • Alexander Stibal
  • Luigi Mariani
  • Roland Wiest
  • Kaspar Schindler
Original Article

DOI: 10.1007/s12021-012-9161-2

Cite this article as:
Rummel, C., Goodfellow, M., Gast, H. et al. Neuroinform (2013) 11: 159. doi:10.1007/s12021-012-9161-2

Abstract

Epileptic seizures are due to the pathological collective activity of large cellular assemblies. A better understanding of this collective activity is integral to the development of novel diagnostic and therapeutic procedures. In contrast to reductionist analyses, which focus solely on small-scale characteristics of ictogenesis, here we follow a systems-level approach, which combines both small-scale and larger-scale analyses. Peri-ictal dynamics of epileptic networks are assessed by studying correlation within and between different spatial scales of intracranial electroencephalographic recordings (iEEG) of a heterogeneous group of patients suffering from pharmaco-resistant epilepsy. Epileptiform activity as recorded by a single iEEG electrode is determined objectively by the signal derivative and then subjected to a multivariate analysis of correlation between all iEEG channels. We find that during seizure, synchrony increases on the smallest and largest spatial scales probed by iEEG. In addition, a dynamic reorganization of spatial correlation is observed on intermediate scales, which persists after seizure termination. It is proposed that this reorganization may indicate a balancing mechanism that decreases high local correlation. Our findings are consistent with the hypothesis that during epileptic seizures hypercorrelated and therefore functionally segregated brain areas are re-integrated into more collective brain dynamics. In addition, except for a special sub-group, a highly significant association is found between the location of ictal iEEG activity and the location of areas of relative decrease of localised EEG correlation. The latter could serve as a clinically important quantitative marker of the seizure onset zone (SOZ).

Keywords

Epileptic focal onset seizures Quantitative EEG High frequency oscillations Pre-surgical evaluation Seizure onset zone 

Abbreviations

CC

equal-time cross-correlation

EEG

electroencephalogram

FLE

frontal lobe epilepsy

Fo

foramen ovale

iEEG

intracranial electroencephalogram

MRI

magnetic resonance imaging

PLE

parietal lobe epilepsy

TCS

total correlation strength

TLE

temporal lobe epilepsy

SCC

slope cross-correlation

SOZ

seizure onset zone

Supplementary material

12021_2012_9161_MOESM1_ESM.pdf (3.9 mb)
ESM 1(PDF 4011 kb)

Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Christian Rummel
    • 1
  • Marc Goodfellow
    • 2
    • 3
  • Heidemarie Gast
    • 4
  • Martinus Hauf
    • 1
  • Frédérique Amor
    • 4
  • Alexander Stibal
    • 5
  • Luigi Mariani
    • 6
  • Roland Wiest
    • 1
  • Kaspar Schindler
    • 4
  1. 1.Support Center for Advanced Neuroimaging (SCAN), University Institute of Diagnostic and Interventional Neuroradiology, InselspitalBern University Hospital, University of BernBernSwitzerland
  2. 2.Systems Biology Doctoral Training Centre, Manchester Institute of BiotechnologyThe University of ManchesterManchesterUK
  3. 3.Centre for Interdisciplinary Computational and Dynamical Analysis (CICADA), School of MathematicsThe University of ManchesterManchesterUK
  4. 4.qEEG group, Department of Neurology, InselspitalBern University Hospital and University of BernBernSwitzerland
  5. 5.Department of Neurosurgery, InselspitalBern University Hospital, University of BernBernSwitzerland
  6. 6.Department of NeurosurgeryBasel University Hospital, University of BaselBaselSwitzerland