Research On The EEG Waveform Simulation System For TMS

Transcranial Magnetic Stimulation (TMS) is a new method in the brain cognition domain, the principle is inducing the induced current by the time-varying magnetic fields to stimulate the cerebral cortex neuron and change it's function. The process is safe, painless, non-invasive, and it can be repeated easily. The research indicated that, 5~25Hz magnetic field could induce excitability. This method is significant undoubtedly for the persons who are sleepy and tired with working continuously.The effects of TMS has the direct relations to the intensity, frequency and profile of the magnetic field. Some experiments confirmed that, the magnetic field which conforms to the physiological rule is possible to induce the brain's active response, and activates human's state of mind. This research is for the purpose of designing a set of equipments, uses in generating the magnetic filed which is similar to the EEG wave's profile, and studies this kind of magnetic field's influence to the cerebral cortex's excitability. First, we used the numerical method to analyze eight-figure coil's magnetic field when it was supplied low frequency current, educed the magnetic field's distribution by Maxwell equations, and drew it's figure with Fortran and Matlab. This job provided the theory basis for the coil design. Take the research above as the foundation, in order to overcome the limitation of the conventional magnetic stimulator, a EEG waveform simulation system for TMS was developed in this paper. This device can generate the time-varying voltage that imitate EEG waveform of the person who under the condition of being excited, and this device is used to supply the current for the coil.Compared with the EEG power spectrum before and after the experiments, we can conclude the pallium is excited obviously when the magnetic decided by the electrowaves of the excited brain is coupled into the brain.