Presence of nonlinearity in intracranial EEG recordings: Detected by Lyapunov exponents

Chang Chia Liu, Deng Shan Shiau, W. Art Chaovalitwongse, Panos M. Pardalos, J. C. Sackellares

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

In this communication, we performed nonlinearity analysis in the EEG signals recorded from patients with temporal lobe epilepsy (TLE). The largest Lyapunov exponent (Lmax) and phase randomization surrogate data technique were employed to form the statistical test. EEG recordings were acquired invasively from three patients in six brain regions (left and right temporal depth, subtemporal and orbitofrontal) with 28-32 depth electrodes placed in depth and subdural of the brain. All three patients in this study have unilateral epileptic focus region on the right hippocampus(RH). Nonlinearity was detected by comparing the Lmax profiles of the EEG recordings to its surrogates. The nonlinearity was seen in all different states of the patient with the highest found in post-ictal state. Further our results for all patients exhibited higher degree of differences, quantified by paired t-test, in Lmax values between original and its surrogate from EEG signals recorded from epileptic focus regions. The results of this study demonstrated the Lmax is capable to capture spatio-temporal dynamics that may not be able to detect by linear measurements in the intracranial EEG recordings.

Original languageEnglish (US)
Title of host publicationData Mining, Systems Analysis, and Optimization in Biomedicine
Pages197-205
Number of pages9
DOIs
StatePublished - Dec 1 2007
EventConference on Data Mining, Systems Analysis, and Optimization in Biomedicine, 2007 - Gainesville, FL, United States
Duration: Mar 28 2007Mar 30 2007

Publication series

NameAIP Conference Proceedings
Volume953
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616

Other

OtherConference on Data Mining, Systems Analysis, and Optimization in Biomedicine, 2007
CountryUnited States
CityGainesville, FL
Period3/28/073/30/07

Keywords

  • Epilepsy
  • Lyapunov exponents
  • Surrogate data

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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