Abstract
A covariance matrix-based subtraction method has recently been proposed to remove interference using two MEG measurements: The first has both target and interfering activities and the second only has the interference. This paper compared covariance matrix-based subtraction with conventional waveform-based subtraction, which requires that the waveforms of interference be equal at every time point between the two measurements. Our analysis showed that covariance-subtraction only requires that the time-average of the squared intensity of interference be equal between the two measurements. As a result, the method is still effective when the onset of interference differs or even their measured waveforms differ between the two measurements. The covariance- and waveform-subtraction methods were both applied to remove the interference caused by response-button-pressing finger movements in auditory-evoked MEG measurements. The results of this application demonstrated the superiority of the covariance-subtraction method over the conventional waveform-subtraction method.
Original language | English (US) |
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Pages (from-to) | 95-102 |
Number of pages | 8 |
Journal | Brain Topography |
Volume | 11 |
Issue number | 2 |
DOIs | |
State | Published - 1998 |
Keywords
- Covariance difference analysis
- Covariance matrix-based subtraction
- MEG
- MUSIC algorithm
- Source localization
- Task and control stimulus conditions
ASJC Scopus subject areas
- Anatomy
- Radiological and Ultrasound Technology
- Radiology Nuclear Medicine and imaging
- Neurology
- Clinical Neurology