Analysis Of Induced Electric Field In Real Rat Head Model During Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses the principle of electromagnetic induction to generate currents in the brain via pulsed magnetic fields. Now it has been widely used in the treatment of psychiatric and brain research. But, before TMS is put into clinical trial, many TMS experiments are undertaken on rats. There have been some promising diagnostic and therapeutic results of TMS on rats. However, rat brains are much smaller than human brains, so the magnetic coil used for human beings would affect more rat brain areas than human brain areas. Therefore, it is necessary to analyze the exact electric field induced by TMS on rat brains. Firstly, the design and construction methods of the stimulating coil were demonstrated in detail on the basis of the analysis of electromagnetic theory. Further, a measurement system of the induced electric field has been designed and built to evaluate the quality of the coil. Secondly, since the computational model of electromagnetic fields have not been applied to the animal at present, a computational method of induced electric fields in the real rat's head model during transcranial magnetic stimulation is presented with the help of 3D reconstructing technology and finite element methods. This method is quite useful to design TMS experiments on rats and interpret results of these experiments. Finally, this paper proposes both parameters of the stimulation coil and its position, which are appropriate for TMS experiments on rats. With the help of these results, design of TMS experiments on rats will be much easier and outcomes of these experiments will have more well-founded explanations.