Transcranial magnetic stimulation (TMS) is the application of short pulses of magnetic energy to the brain. In the case of depression, these pulses are aimed at the area of the brain which controls mood, called the limbic system. When the magnetic pulses hit nerve cells in this area, they cause the nerve cells to become more active. Altering the activity of the cells responsible for mood is thought to improve major depression disorder.
Clinical trials have reported significant improvement in depression symptoms with TMS.