IDENTIFICATION OF CENTRAL SULCUS BY USING SOMATOSENSORY EVOKED MAGNETIC-FIELDS AND BRAIN SURFACE MR IMAGES - 3-DIMENSIONAL PROJECTION ANALYSIS

We present a novel non-invasive technique for identification of the ce ntral sulcus on the brain surface by using three-dimensional magnetic resonance imaging (3D-MRI) in combination with somatosensory evoked ma gnetic fields (SEFs). The central sulcus was supposed anatomically on the brain surface by using 3D-MRI. On the other hand, the primary soma tosensory area is determined by using SEF data with median nerve stimu lation. Superimposition of the SEFs of the 25 ms response onto the bra in surface MR images clearly demonstrated the dipole source located in the gyral fold just behind the supposed central sulcus in all subject s analyzed. Three-dimensional reconstruction of the brain surface imag e data facilitated visualizing the precise anatomical localization of the magnetic field activities from any angle and measuring the distanc e from the source to any point of interest. The potential clinical app lication of this technique is discussed.