1. A method of stimulating a target deep brain region using multiple Transcranial Magnetic Stimulation (TMS) electromagnets, the method comprising: positioning a first TMS electromagnet over a first predetermined cortical region having a first-order connection to a target deep brain region; positioning a second TMS electromagnet over a second predetermined cortical region having a first-order connection to the target deep brain region; inducing modulation of at the first and second predetermined cortical regions by applying TMS from both the first and second TMS electromagnets; and inducing modulation of the deep brain region by spatial summation of the modulation from the first and second cortical regions.