A new study is advancing the possibility that mentally ill patients who do not respond to conventional therapies may benefit from battery-powered electrodes surgically implanted in their brains.

The procedure, called Deep Brain Stimulation (DBS), uses a pacemaker-like device to deliver small, steady electrical charges to specific brain circuits that control our moods.

While DBS has been approved by the FDA since 1997 to treat the symptoms of movement disorders - essential tremor, Parkinson's disease and dystonia– its use in mental illness is experimental.  Only a few scientists have tested DBS on just several dozen psychiatric patients suffering from treatment-resistant depression and obsessive-compulsive disorder.

The most recent study, published Monday in the online edition of Archives of General Psychiatry, includes not only 10 patients with major depressive disorder, but also 7 patients with bipolar II disorder, who typically have frequent, severe depressive episodes and are at a high risk of suicide.