Calculating the electric fields in the human brain by deep transcranial magnetic stimulation

Stimulation of deeper brain structures by transcranial magnetic stimulation (TMS) may be beneficial in the treatment of several neurological and psychiatric disorders. This paper presents numerical simulation of deep transcranial magnetic stimulation (dTMS) by considering double cone, Hand Halo coils. Three-dimensional distributions of the induced electric fields in realistic head model by dTMS coils were calculated by impedance method and the results were compared with that of standard figure-of-eight coil. Simulation results show that double cone and H-coils have significantly deep field penetration at the expense of induced higher and wider spread electrical fields in superficial cortical regions. The combination of Halo coil with a conventional circular coil produce deeply penetrating electric field the same as double cone and H-coils, but the stimulation in superficial brain tissues are much lower.