"Happiness is a warm electrode":

For the past 20 years, [Diane Hire] has suffered from severe depression, a crippling strain of the disease that afflicts as many as four million people. Years of therapy, at least 10 different drugs and six courses of the whole-brain shock technique known as electroconvulsive therapy (ECT) all failed to bring Hire lasting relief. Her final hope is this operation, a radical form of neurosurgery called deep-brain stimulation, or DBS.

Whereas ECT -- a treatment that's been demonized in movies like One Flew over the Cuckoo's Nest but is still used on roughly 100,000 patients a year -- floods the brain with electricity from the outside, this technique delivers a smaller dose of better-targeted current to an area of the brain believed to be a key regulator of mood. Wires thread beneath the skin from their place in the brain and plug into two battery-run stimulators implanted in the chest. About the size of an iPod nano, each stimulator constantly pumps out current, bathing a small region of brain tissue in electricity. If ECT is the equivalent of slapping defibrillators against a heart-attack victim's chest, deep-brain stimulation is the pacemaker that prevents the attack in the first place.