It's just before 9 a.m., and operating room No. 11 at the Cleveland Clinic is a portrait of cool efficiency.
An awake and alert 59-year-old patient with severe tremors is having an electrode implanted deep inside her brain. If successful, this procedure could almost eliminate her debilitating condition.
Dr. Ali Rezai, the lead neurosurgeon at this Cleveland medical facility, turns on the implant's electrical current and, almost instantaneously, the woman's tremors start to recede.
This remarkable procedure has been used on patients with Parkinson's disease and other movement disorders for more than a decade, and now doctors have started employing it to ease persistent, untreatable cases of depression and obsessive-compulsive disorder.
Welcome to the brave new world of deep-brain stimulation, where surgeons can take a patient from sadness to joy, from fear to serenity, in just a moment. It's a strange ride, but two women say they had no choice but to climb aboard.
Before she received deep-brain stimulation, Cindy, a Michigan woman, could barely get out of bed. She suffered from severe and incurable depression.
"I wanted to die," she said. "I just hoped something would happen that ... you know, that I could die."
She got so desperate that at one point, she even tried to commit suicide.
As with most severely depressed patients, Cindy was treated with prescription drugs, a dozen or more, and psychotherapy, she said. But her depression only deepened as the years wore on. She tried shock therapy, too, but the side effects were increasingly debilitating.
"Short-term memory loss, and then long-term memory loss," she said.
A few hundred miles away in Iowa, 37-year-old Kelly was living through her own kind of hell with an extreme case of obsessive-compulsive disorder.
"The outside world turned into this big contaminated place," she said. "I had this thing with people contact -- didn't know if their hands were washed, didn't know where they had been."
Her husband, Matt, could only watch as she became trapped by her fears.
"It was like being trapped in a box. I was outside looking in, and she was inside looking out. I could not get her to come outside," he said.
Both Cindy and Kelly elected to undergo five-hour operations during which tiny electrodes are implanted inside their brains. Only 50 people worldwide have been treated with deep brain stimulation for depression or obsessive compulsive disorder.
After surgery, psychiatrists will electrically stimulate the women's mood and anxiety centers, using a handheld device. In other words, with the touch of a keypad, Kelly's obsessions and Cindy's depression may start to ease, or they may not. Deep-brain stimulation is largely an experiment of last resort.
"When you go into the brain, millimeters matter. You go from 1 millimeter and you move 5 millimeters, and it does something totally different to the whole body," said Dr. Donald Malone. "And so the complexity that's involved in the brain is amazing.
"There's no question: It's still an investigational procedure," he said.
Kelly was aware of that but said she believed the risk was worth it.
"I didn't want to live the rest of my life the way I was, and I thought there might be a chance, so whatever it took was what I was going to do," she said.