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An estimation method for multiple sources of magnetoencephalogram is proposed. In the proposed method, the assumed dipoles are arranged on and oriented perpendicular to the surface of the cerebral cortex based on the hypothesis of the functional columnar structure. Since the positions and orientations of the assumed dipoles are given beforehand, the magnetic fields that originate from the assumed dipoles are predictable. Using a coefficient of determination between the predicted and measured magnetic fields as a criterion, the electric sources of the N20m component of the somatosensory evoke fields when the central nerves of the wrists are stimulated bilaterally and the N100m component of the auditory evoked fields are localized. The positions of the dipoles are close to those localized by the moving dipole method.

Somatosensory cortex receives afferent inputs from skeletal muscles and joints while a voluntary movement is conducted. Although this sensory feedback may regulate the efferent motor control signals generated in the motor cortex, the relationship between the afferent sensory signals and the efferent motor signals is still unclear. In this study, we investigated the relationship between the afferent signals elicited by an electrical stimulus of a peripheral nerve and the efferent signals produced by a transcranial magnetic stimulation (TMS) of the motor cortex. The changes of motor evoked potentials (MEPs) elicited by TMS following an electrical stimulus of a median nerve were observed. The results showed that the MEPs were significantly attenuated when the inter-stimulus interval (ISI) between the electrical stimulus and the TMS was 20 ms, and that the MEPs were significantly enhanced when the ISI was longer than 35 ms. Furthermore, the brain condition which affected the MEPs was evaluated with the somatosensory evoked fields (SEFs) measured with magneto-encephalography (MEG). It was suggested that the activation and direction of the current dipole in the primary somatosensory cortex was related to the effect of the afferent signals on the motor function.

This study investigated current distribution in the female abdomen using experimental and computer models of magnetic stimulation for treatment of urinary incontinence. Four experimental models and two computer models were used to simulate current distributions. In the performed computations of eddy current distribution, 18 cross-sectional images (interslice gap, 10 mm; slice numbers 750-920) of a female pelvic region from the NPAC/OLDA Visible Human Viewer were used. The influence of tissue inhomogeneity on current distribution were investigated using experimental models. In the region of pelvic floor muscles at depths of 20 mm and 50 mm from the experimental model, analysis of eddy current distribution could not be performed as a homogeneous conductor due to large differences in angles and summation of currents between Models I and IV. Within the region of the bladder and other organs at a depth of 100 mm from the experimental model, the pelvis and other tissues exerted little influence on current distribution.