TY - GEN
T1 - Performance of an MEG adaptive-beamformer technique in the presence of correlated neural activities
T2 - IEEE International Symposium on Biomedical Imaging, ISBI 2002
AU - Sekihara, Kensuke
AU - Nagarajan, Srikantan S.
AU - Poeppel, David
AU - Marantz, Alec
PY - 2002
Y1 - 2002
N2 - The influence of temporarily correlated source activities on neuromagnetic reconstruction by adaptive beamformer techniques is investigated. It is known that the spatial filter weight of an adaptive beamformer cannot perfectly block correlated signals. This causes two major influences on the reconstruction results: time course distortions and reductions in reconstructed signal intensities. The reduction in signal intensity for sources with a medium degree of correlation is found to be insignificant. The time course distortion for such sources, however, may not be negligible. Our analysis shows that the magnitude correlation coefficient between two correlated sources can be accurately estimated by using the beamformer outputs. A method of retrieving the original time courses using estimated correlation coefficients is developed. Our numerical experiments demonstrate that reasonably accurate time courses can be retrieved from considerably distorted time courses even when the signalto-noise ratio is low.
AB - The influence of temporarily correlated source activities on neuromagnetic reconstruction by adaptive beamformer techniques is investigated. It is known that the spatial filter weight of an adaptive beamformer cannot perfectly block correlated signals. This causes two major influences on the reconstruction results: time course distortions and reductions in reconstructed signal intensities. The reduction in signal intensity for sources with a medium degree of correlation is found to be insignificant. The time course distortion for such sources, however, may not be negligible. Our analysis shows that the magnitude correlation coefficient between two correlated sources can be accurately estimated by using the beamformer outputs. A method of retrieving the original time courses using estimated correlation coefficients is developed. Our numerical experiments demonstrate that reasonably accurate time courses can be retrieved from considerably distorted time courses even when the signalto-noise ratio is low.
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U2 - 10.1109/ISBI.2002.1029437
DO - 10.1109/ISBI.2002.1029437
M3 - Conference contribution
AN - SCOPUS:84948666980
T3 - Proceedings - International Symposium on Biomedical Imaging
SP - 1019
EP - 1022
BT - 2002 IEEE International Symposium on Biomedical Imaging, ISBI 2002 - Proceedings
PB - IEEE Computer Society
Y2 - 7 July 2002 through 10 July 2002
ER -