Scientists have long dreamed of non-invasively stimulating parts of the brain to further brain research and treat illness. About a century ago, researchers first used weak magnetic fields to stimulate optic nerve cells, allowing subjects to perceive flashes of light, but they couldn't exactly "fire up" brain cells. In 1985, that all changed as scientists at the University of Sheffield, England, reported the first success at triggering brain cells, using neither surgery nor anesthesia, but "transcranial magnetic stimulation" (TMS).

TMS uses electrical energy passed through a coil of wires, creating a powerful magnetic field. Applied to the head, this field painlessly passes through both skin and bone to activate the brain. As several studies have suggested that parts of the brain, especially the frontal area, may be key to mood regulation, TMS is seen as a possible tool for treating depression. In experimental treatments based on these studies, TMS has, in fact, stimulated "feel good" areas of the brain, sparking a good deal of interest.

Researchers at the National Institute of Mental Health suggest that using TMS on the brain's frontal area may indeed help severely depressed patients as effectively as electro-convulsive therapy (ECT) but without its side effects. However, it's too early to tell if TMS is as promising as some research suggests since worldwide, there are only about 1,000 case studies, with data published on 200. Likewise, since TMS has been used to treat cases where other conventional treatments have failed, it's reasonable to believe that TMS could also succeed where popular alternative treatments, such as St. John's wort and 5-HTP, have not.

At this early stage, researchers are still trying to answer several unknowns, like how to most accurately stimulate a part of the brain, the effects TMS has on brain circuitry, the optimal treatment frequency, and several others. Critics suggest it may be too early to use TMS, even in clinical studies, when so many questions remain, yet, supporters of the research believe TMS is groundbreaking, and the more it is studied, the closer researchers will come to really unraveling the mysteries of mental illness, especially depression.