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COST Meeting Istanbul 2005

COST Meeting Istanbul 2005. Graz University of Technology BCI Lab. Graz University Applied Neuropsychology. BCI Lab Graz. Gert Pfurtscheller Alois Schlögl Gernot Müller-Putz Clemens Brunner Bernhard Graimann Eva Höfler Claudia Keinrath Robert Leeb Reinhold Scherer Doris Zimmermann.

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COST Meeting Istanbul 2005

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  1. COST Meeting Istanbul 2005 Graz University of Technology BCI Lab Graz University Applied Neuropsychology

  2. BCI Lab Graz • Gert Pfurtscheller • Alois Schlögl • Gernot Müller-Putz • Clemens Brunner • Bernhard Graimann • Eva Höfler • Claudia Keinrath • Robert Leeb • Reinhold Scherer • Doris Zimmermann

  3. Current projects @ BCI Lab • BIOSIG – An open source software library for biomedical signal processing • Multivariate Autoregressive modeling including COH, pCOH, PDC, DTF, ffDTF, etc. • Time-varying (non-stationary) analysis • Single-Trial classification • Quality control and artefact processing • Standardization of Biosignal processing

  4. BIOSIG An open source software library for biomedical signal processing http://biosig.sf.net

  5. Categories within BIOSIG • T100: Data Acquisition • T200: Data Formats • T250: Preprocessing (Trigger, Artifacts, etc.) • T300: Signal Processing • T400: Classification, Statistics • T490: Evaluation criteria • T500: Presentation, Output • T550: Topographic Mapping • T600: Interactive Viewer and Scoring

  6. Automated artifact processing • Correction of EOG artifacts using regression analysis • Artifact detection • Overflow / Saturation detection • Detection of muscle artifacts with inverse filters • Corrupted sample values are encoded with „Not-a-number“ (NaN) and are skipped in the further analysis • Version 2.0 of GDF data format

  7. Data storage • Support of all available dataformats • Combine best features of all formats in GDF • GDF 1.x • Derived from EDF, multiple data types, support of events/annotations/markers, overflow, Y2K, ... • New Features of GDF 2.0 • Gender, handedness, Weight, Height, Recording location (place), impedance and position for each electrode, etc.

  8. Viewing and Scoring Software

  9. Signal processing (I) • Autoregressive (AR) model • Burg, Levinson-Durbin, Lattice estimators • Adaptive Autoregressive (AAR) model • LMS, RLS, Kalman filtering • Multivariate Autoregressive (MVAR) • Nutall-Strand, Levinson, „multichannel Yule-Walker“, etc. ! All estimators are able to handle „missing values“ !

  10. Signal processing (II) • Spectrum • Coherence (COH) • Partial coherence (pCOH) • Partial directed coherence (PDC) • Directed transfer function (DTF) • Full-Frequency DTF (ffDTF) • Directed coupling (DC) • Phase

  11. PDC (Hypothesis: PDC>0) Subject K3 Left hand 1 0 Coupling almost all the time in all frequencies !?

  12. DTF (Hypothesis: DTF>0) Subject K3 Left hand 1 0 Coupling almost all the time in all frequencies !?

  13. Event-related PDC (Hypothesis: PDC != ref) Subject K3 Left hand ref=pdc(0-3s) pdc>ref pdc<ref Increases and decreases of coupling can be observed !

  14. Event-related PDC (Hypothesis: PDC != ref) PDC (Hypothesis: PDC != ref) Subject K3 Right hand ref=pdc(0-3s) pdc>ref pdc<ref Increases and decreases of coupling can be observed !

  15. Future plans • GDF Version 2.0 • Improvement of automated quality control and artifact processing. • Statistical significance test for MVAR parameters -> http://biosig.sf.net • Improve visualization of MVAR results -> http://biosig.sf.net • Collaborations based on available methods.

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