MEG Co variance difference analysis: A method to extract target source activities by using task and control measurements

K. Sekihara, D. Poeppel, A. Marantz, C. Phillips, H. Koizumi, Y. Miyashita

Research output: Contribution to journalArticle


A method is proposed for extracting target dipolesource activities from two sets of evoked magnetoencephalographic (MEG) data, one measured using task stimuli and the other using control stimuli. The difference matrix between the two covariance matrices obtained from these two measurements is calculated, and a procedure similar to the MEG-multiple signal classification (MUSIC) algorithm is applied to this difference matrix to extract the target dipole-source configuration. This configuration corresponds to the source-configuration difference between the two measurements. Computer simulation verified the validity of the proposed method. The method was applied to actual evoked-field data obtained from simulated task-andcontrol experiments. In these measurements, a combination of auditory and somatosensory stimuli was used as the task stimulus and the somatosensory stimulus alone was used as the control stimulus. The proposed covariance difference analysis successfully extracted the target auditory source and eliminated the disturbance from the somatosensory sources.

Original languageEnglish (US)
Pages (from-to)87-97
Number of pages11
JournalIEEE Transactions on Biomedical Engineering
Issue number1
StatePublished - Dec 1 1998



  • Array signal processing
  • Biomagnetics
  • Biomedical electromagnetic imaging
  • Biomédical signal processing
  • Functional brain imaging
  • Inverse problems

ASJC Scopus subject areas

  • Biomedical Engineering

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