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; and applying TMS from both the first and second TMS electromagnets so that the applied TMS induces spatial summation of signals received at the target deep brain region from the first and second cortical regions.