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.

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 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% 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% had complete relief from their symptoms, while 60% got at least somewhat better.

That's not as effective as electroconvulsive therapy, which has full remission rates of around 60%, 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.