Abstract / Poster: 1-4 Basic Meg: Pain and Somatosensory Function (2) 1-4-6: Waveform Analysis of Neuromagnetic Response by Mixed Aef and Sef Using Dsvd

inter-stimulus intervals more than one second. In 5Hz periodical median nerve stimuli common BSS patterns of the primary somatosensory cortex, power electric noise, eye blinks, and alpha waves were observed in seven subjects. Although the absolute summation of off diagonal elements of correlation matrices is minimized in the algorithm of the decorrelation method, the correlation between BSS components still remains. For a trivial example there are two BSS components necessary to express power electric noise, which are not independent. That is, the decorrelation method is not perfectly the independent component analysis but the blind source separation. Taking advantage of little cross-correlation between BSS components we could find typical BSS components related to periodical median nerve stimuli. In each individual case their BSS patterns were found as one of two types with ipsilateral dipole pattern near SI:1) activity of ipsilateral primary somatosensory cortex,2) phase locked activity of alpha or beta wave. Another typical patterns near contralateral SI were the BSS components necessary to spatial expansion of the waveform of SEF.The other typical patterns of dipole related to periodical median nerve stimuli were observed near the second contralateral somatosensory or the auditory cortex.