Volumetric localization of somatosensory cortex in children using synthetic aperture magnetometry

BACKGROUND: Magnetic signal from the human brain can be measured noninvasively by using magnetoencephalography (MEG). OBJECTIVE: This study was designed to localize and reconstruct the neuromagnetic activity in the somatosensory cortex in children. MATERIALS AND METHODS: Twenty children were studied using a 151-channel MEG system with electrical stimulation applied to median nerves. Data were analyzed using synthetic aperture magnetometry (SAM). RESULTS: A clear deflection (M1) was clearly identified in 18 children (90%, 18/20). Two frequency bands, 30-60 Hz and 60-120 Hz, were found to be related to somatosensory cortex. Magnetic activity was localized in the posterior bank of the central sulcus in 16 children. The extent of the reconstructed neuromagnetic activity of the left hemisphere was significantly larger than that of the right hemisphere ( P<0.01). CONCLUSION: Somatosensory cortex was accurately localized by using SAM. The extent of the reconstructed neuromagnetic activity suggested that the left hemisphere was the dominant side in the somatosensory system in children. We postulate that the volumetric characteristics of the reconstructed neuromagnetic activity are able to indicate the functionality of the brain.