Systematic Source Estimation of Epileptiform Discharges by a Combination of Independent Component Analysis and Rap-Music.
Abstract number :
3.175
Submission category :
Year :
2001
Submission ID :
122
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
K. Kobayashi, MD, Dept. of Child Neurology, Okayama University Medical School, Okayama, Japan; T. Akiyama, MD, Dept. of Child Neurology, Okayama University Medical School, Okayama, Japan; T. Nakahori, Dept. of Child Neurology, Okayama University Medical S
RATIONALE: We propose a combination of independent component analysis (ICA) and RAP-MUSIC (recursively applied and projected multiple signal classification) as a new approach to dipole source estimation of epileptiform discharges. The estimation is minimally influenced by subjective decisions in this analysis. We applied this method to real EEG spikes.
METHODS: Unaveraged EEG data including an array of spikes from three patients were decomposed by ICA. The spikes were extracted from the background as spatio-temporal components, each component having a fixed potential field distribution and a waveform maximally independent from the others. The complete separation between the spikes and the background was objectively proven by reconstruction of the EEG from the decomposed components. Source estimation was performed by applying RAP-MUSIC to the spatial information defined by the ICA components that showed epileptiform activity in their waveform.
RESULTS: RAP-MUSIC based on ICA could estimate epileptic sources which were close to the general locations of maximal intracerebal epileptic fields in the three patients. The present analysis proceeded without introduction of subjective decision after data selection. The separation of epileptiform discharges from the background is essential for this analysis, and was successfully performed with ICA in the real EEG data.
CONCLUSIONS: RAP-MUSIC based on ICA appears promising for estimation of epileptic sources with minimal dependence on subjective decisions in the process of analysis. In particular, it was not necessary to select the number of sources.
Support: Grant MT-10189 of the Canadian Institutes of Health Research in part.