Learning from Switched-Off Brains.

"Virtual damage" from pulsed magnetic fields is providing new insights about the brain. The procedure may help treat disorders--or even boost mental performance. Transcranial magnetic stimulation (TMS), as the approach is called, may someday be used to relieve a variety of disorders caused by malfunctioning neural circuits. For example, the U.S. Food and Drug Administration is investigating TMS as a treatment for depression; the practice is already permitted in Canada. Other potential therapeutic targets include obsessive-compulsive disorder, schizophrenia, Parkinson's disease, dystonia (involuntary muscle contractions), chronic pain and epilepsy. In addition to treatments for damaged brains, recent studies suggest that TMS may be used to improve normal ones, by temporarily enhancing cognition. Researchers are gaining insights into fundamental neuronal mechanisms such as speech and spatial perception, which lets people quickly orient themselves in a room, find food, or cross a street safely.Early TMS research found that it could cause seizures or epileptic convulsions, depending on the intensity, frequency, duration and level of the magnetic stimulation, and the consequences of long-term exposure are unknown. So far the FDA has not approved the method for any disorder. Despite the open questions, one thing is certain: TMS is a stimulating area for scientific inquiry.