TMS stands for transcranial magnetic stimulation. It is used to treat depression by stimulating the brain non-invasively using an electromagnetic field, similar to those magnetic fields produced by an MRI machine. During TMS Therapy, a magnetic field is administered in very short pulses to the part of your brain that research has demonstrated to be associated with depression. The typical initial outpatient course of treatment is about 30-60 minutes daily over 4-6 weeks.