Performance of an MEG adaptive-beamformer source reconstruction technique in the presence of additive low-rank interference

IEEE Trans Biomed Eng. 2004 Jan;51(1):90-9. doi: 10.1109/TBME.2003.820329.


The influence of external interference on neuromagnetic source reconstruction by adaptive beamformer techniques was investigated. In our analysis, we assume that the interference has the following two properties: First, it is additive and uncorrelated with brain activity. Second, its temporal behavior can be characterized by a few distinct activities, and as a result, the spatio-temporal matrix of the interference has a few distinctly large singular values. Namely, the interference can be modeled as a low-rank signal. Under these assumptions, our analysis shows that the adaptive beamformer techniques are insensitive to interference when its spatial singular vectors are so different from a lead field vector of a brain source that the generalized cosine between these two vectors is much smaller than unity. Four types of numerical examples verifying this conclusion are presented.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Validation Study

MeSH terms

  • Algorithms*
  • Artifacts*
  • Brain / physiology
  • Brain Mapping / methods*
  • Computer Simulation
  • Diagnosis, Computer-Assisted / methods*
  • Feedback
  • Humans
  • Magnetoencephalography / methods*
  • Models, Neurological*
  • Reproducibility of Results
  • Scattering, Radiation
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted*