Time-frequency microstructure of event-related EEG desynchronization and synchronization.

Piotr J. Durka¹, Dobiesaw Ircha², Christa Neuper³ Gert Pfurtscheller⁴

Medical & Biological Engineering & Computing, Vol. 39, No. 3, May 2001, © IEE. Click here to download PostScript.

Abstract:

We present a new method for analysis of event-related EEG phenomena, in particular ERD/ERS related to a voluntary movement, which offers:

• high time-frequency resolution, and hence also increased ERD/ERS sensitivity (especially in the gamma band, where improvement may exceed order of magnitude),
• possibility to analyze the whole picture of energy changes at once, without setting a priori the analyzed frequency bands,
• parametric description of signal's structures.

The main idea is based upon averaging energy distributions of single EEG trials in the time-frequency plane. As the estimator for signal's energy density we choose matching pursuit with stochastic Gabor dictionaries. Other possible estimates are presented on simulated signal and discussed briefly. Consistence of results with previous findings is evaluated on the data from a classical voluntary finger movement experiment.

Keywords: ERD, ERS, ERP, gamma activity, time-frequency, matching pursuit.

Footnotes

... Durka¹

... Ircha²

Laboratory of Medical Physics, Warsaw University, ul. Hoza 69, 00-681 Warszawa, Poland. This work was supported by Polish State Committee for Scientific Research grant 8T11E014016.

... Neuper³

Ludwig Boltzmann Institute of Medical Informatics and Neuroinformatics, Graz University of Technology

... Pfurtscheller⁴

Department of Medical Informatics, Institute for Biomedical Engineering, Graz University of Technology, Inffeldgasse 16a, A-8010 Graz, Austria. This work was supported by the "Austrian Fonds zur Förderung der wissenschaftlichen Forschung" (Project 12407)