Time-delayed decorrelation for the identification of cardiac artifact components in MEG data.
The time-delayed decorrelation (TDD) Independent Component Analysis (ICA) applied to continuous multichannel magnetoencephalographic (MEG) recordings is a straightforward calculation in the time domain: Its main ingredient is a calculation of the correlation between signals having different time shifts with respect to each other. The equivalent mathematical representation in the frequency domain and a simple simulation show that TDD exploits different complex frequency spectra of the sources. Applying ICA to 80-channel whole head MEG data obtained under visual stimulation we can assign five of the 80 source components to the cardiac artifact. Their complex spectra exhibit a randomly distributed phase showing that TDD is capable of isolating quasi-periodic signals even for the case of an unspecified phase.
Sander
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Physikalisch-Technische Bundesanstalt, 10587 Berlin, Germany. till.sander@ptb.de
Lueschow
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Curio
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Trahms
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D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D005583:Fourier Analysis; D006339:Heart Rate; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation*; D008432:Mathematical Computing; D025341:Principal Component Analysis; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*