CHICAGO – A machine that sends magnetic pulses into a patient's brain has become the new frontier of depression treatment, promising to ease symptoms for those who have found little relief from medication or talk therapy.

The treatment, known as trans­cranial magnetic stimulation, or TMS, is part of a wave of technologies that attempt to jolt the brain back to health. It caught on quickly after the Food and Drug Administration approved its use six years ago.

Though some have questioned the technology's effectiveness, more insurance companies are starting to cover it, helping with a price tag that can reach $10,000 for six weeks of treatment.

"What this does is raises [your mood] up to normal," a 55-year-old woman from the western suburbs said after finishing a treatment session at Linden Oaks at Edward in Naperville, Ill. "You can operate."

Stimulative brain therapies have been around for decades, the best known being electroconvulsive therapy, a technique that uses an electric current to cause a seizure. It was portrayed as a mind-erasing menace in the movie "One Flew Over the Cuckoo's Nest," though psychiatrists say the procedure is safe today.

Other methods use implanted devices to send electrical pulses to the vagus nerve — a transmission line that carries messages to the brain's mood center — or to the brain itself. Some studies have found that these techniques help to elevate the moods of people with severe depression.

Dr. Mark George, a South Carolina psychiatrist who edits the medical journal Brain Stimulation, said TMS produces similar effects without the need for surgery.

A patient sits in a chair that resembles something from a dentist's office as a device containing the magnetic coil is placed on his head. When it's activated, George said, magnetic pulses penetrate the skull and stimulate nerve cells — the Linden Oaks patient described the sensation as "having a woodpecker sitting on your head" — provoking a therapeutic response.

George acknowledged that the technology doesn't work for everyone. Early studies, which relied on subjects who had been taken off their medications, found that only about 15 percent saw their depressive symptoms go away.

But later research that allowed subjects to stay on their meds, which George called a more true-to-life test, found that 40 percent had complete relief from their symptoms, while 60 percent got at least somewhat better.

That's not as effective as electroconvulsive therapy, which has full remission rates of around 60 percent, but George said that treatment requires patients to be anesthetized and is known to cause memory and cognitive problems in some.

TMS, by contrast, requires no sedation, and its biggest complication appears to be discomfort where the magnets are placed on the head.

"It's a highly effective treatment and has only trivial side effects," said Dr. Jesse Viner, medical director at north suburban Evanston's Yellowbrick psychiatric health care center. "There's no persistent adverse effect. You can have a little bit of a headache or facial pain, but that quickly subsides, and in our experience, by the time people have their third or fourth treatment, they're OK."

Questions remain about the effectiveness of the treatment, but more than 100 million people now have insurance coverage for it, said Dr. David Brock of Neuronetics, the Pennsylvania-based company that sought FDA approval for its TMS machines.

Research is turning to other possible uses, from migraines to Parkinson's disease to post-traumatic stress disorder.