Title: Estimating multiple sources in somatosensory area to SEF of finger stimulus using SVD and time-frequency analysis

Authors: Bong-Soo Kim, Yoshinori Uchikawa

Addresses: Department of Electronic and Computer Engineering, Tokyo Denki University, Ishizaka, Hatoyama, Hiki-gun, Saitama 350-0394, Japan; MEG Center, Department of Neurosurgery, Seoul National University Hospital, Seoul, Korea. ' Department of Electronic and Computer Engineering, Tokyo Denki University, Ishizaka, Hatoyama, Hiki-gun, Saitama 350-0394, Japan

Abstract: In order to discriminate multiple sources in the somatosensory area of the human cortex, we measured the somatosensory evoked field (SEF) with three different finger stimulations. First, the proposed method combining singular value decomposition and time-frequency analysis was applied to the measured SEF data for discrimination of second somatosensory (SII) activity from primary somatosensory (SI) activity overlapping in time. The SII activity was represented by the reconstructed SEF data using the fourth (the thumb) and fifth (fourth finger) singular value, respectively. Second, the frequency of the dominant power spectrum in each SEF data was investigated and the frequency of the fourth finger stimulation existed between the thumb (16-18 Hz) and little finger (13-15 Hz). Source localisation was done by the SEF data to the fourth finger stimulation with different frequency ranges (13-15 Hz and 16-18 Hz BPF). We conclude that the proposed method is useful for discriminating multiple source activities of the somatosensory area overlapping in time.

Keywords: singular value decomposition; SVD; somatosensory evoked field; SEF; time-frequency analysis; human cortex; second somatosensory activity; median nerve; ulnar nerve; finger stimulations; human brain function; signal processing; human fingers.

DOI: 10.1504/IJMIC.2008.021472

International Journal of Modelling, Identification and Control, 2008 Vol.4 No.4, pp.323 - 330

Published online: 28 Nov 2008 *

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