Analysis Of Head Electric Field And The Effect On Nerve Function Of Magnetic Stimulation

Magnetic stimulation is a relatively new technique of non-invasive and painless technology of the central and peripheral neural tissues. It takes advantage of low-frequency time-variant magnetic field to couple external energy into human neural-muscular system. In the past decades, magnetic stimulation has grown dramatically in popularity and been used in several applications in medical and clinical research.According to the Natural Science Foundation of Hebei Province under Grant E2006000037, a realistic head model used in Finite Element Method has been developed from MRI. The electromagnetic field induced in the head by magnetic stimulation has been analyzed. The electromagnetic field distributions produced by four kinds of coils have been analyzed respectively. The effect of point magnetic stimulation on brain activities has been studied. The magnetic stimulation hardware system has been designed. The main research work is as follows:1. Electromagnetic field simulation based on transcranial magnetic stimulation using 3D realistic head modelThe mathematic model used in the simulation of magnetic stimulation has been described in detail. The 3D realistic head model has been build from MRI. The input current in the coil of magnetic stimulation system has been calculated. The distribution of electromagnetic field during the magnetic stimulation on the head has been analyzed. Using the simulation, the stimulation sites could be located precisely and the efficiency of magnetic stimulation experiments could be improved.The electromagnetic fields produced by four different kinds of coils have been analyzed. The effect of three kinds of windings of circle coil on the electromagnetic distribution has also been analyzed.2. Researches on the effect of magnetic stimulation at point on brain activities The EEG is recorded and analyzed when the subjects is stimulated at SHENMEN point by magnetic stimulation in different frequency.The results show magnetic stimulation at SHENMEN point make the healthy people produce more slow-wave components and less fast-wave components than that the healthy people produced in quiet. The single pulse magnetic stimulation is more efficient than the repetitive magnetic stimulation. With the frequency increased, the action effect became weakened.This result is useful for deeper research on the effect of magnetic stimulation on neural function.3. Design of single pulse magnetic stimulation systemThe magnetic stimulation system consists of main circuit part and control circuit part. The components used in each part are high speed and high precision elements, and these ensure the high performance of the whole system. This system can meet the primary need of single pulse magnetic stimulation.