Abstract
A high-efficiency transcranial magnetic stimulation (TMS) is evolving for therapy in brain neurological disorders such as epilepsy, depression, Alzheimer's, and Parkinson's diseases. The fundamental theory of TMS for the interactions between biological tissue and electromagnetic field can help readers to thoroughly understand, thus driving the technology ahead in the future. To this end, this chapter presents an overview of the theory of TMS that includes the operation principle, the mathematical model for the effect of electromagnetic induction on neuronal cable, then developing an optimized design for the TMS system. TMS-induced electric field plays a dominant factor in the efficiency of brain stimulation. The spatially-varying electric field determines whether to activate nerve fibers and result in depolarization of the neurons in the brain. In this chapter, the mathematical model is presented to specifically demonstrate the influence of TMS-induced electric field on nerve fiber in the brain. Most of all, the electric field induced by the magnetic pulsing is directly determined by the TMS circuit and coil design, thus providing an optimized design for TMS clinical applications. Â