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30 December 1998 Multivariate spectral analysis of the beat-to-beat sampled cortical NIRS signals and the heart-rate variability
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Heart-beat-synchronous variations represent a significant noise during functional near-infrared spectroscopy (NIRS) measurements of the brain. ECG-synchronous sampling allows the heart beat correlated pulsatility to be removed from NIRS-signals. During visual stimulation the measured cortical oxy- and deoxy-hemoglobin (oxy-Hb, deoxy-Hb) responses showed a factor > 2 improved signal to noise ratio in comparison to a fixed sampling frequency. The beat- to-beat concentrations of oxi-Hb, deoxi-Hb, the redox status of cytochrome-oxydase (Cyt-Ox) as well as the heart rate variability were analyzed in the frequency domain in order to find a possible correlation between the concentrations and the cardiovascular rhythms. A coherence analysis revealed a close link of these signals in the low frequency band (LF, 0.05 - 0.15 Hz) and the high frequency band (HF, 0.2 - 0.35 Hz). For the different concentration signals a different degree in coherence in the LF- and HF-bands could be observed. Spectral analysis revealed that the cardiovascular rhythms (LF and HF) may represent a noise source in the NIRS-signals which might be removed by special digital filters.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. Scholz, Matthias Kohl-Bareis, Christian Nolte, Carsten Hennig, and Arno Villringer M.D. "Multivariate spectral analysis of the beat-to-beat sampled cortical NIRS signals and the heart-rate variability", Proc. SPIE 3566, Photon Propagation in Tissues IV, (30 December 1998);


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