Chantal Remeny is propped up on the operating table at Toronto Western Hospital, her head encased in a medieval-looking metal frame to hold it steady.
Neurosurgeon Andres Lozano has just peeled back a large swatch of skin from her skull, and drilled holes. Now, he is inserting two electrodes deep into her grey matter and zapping her with jolts of low-voltage electricity to see what kind of reaction the current will elicit as he targets different areas of the brain.
Ms. Remeny, a 40-year-old physiotherapist from Toronto, is conscious during the procedure. She is stone-faced, with the grey pallor and vacant eyes of a person suffering from severe, debilitating depression.
Then, her face lights up noticeably: She notes that the medical team's scrubs are a vivid blue, begins moving her arms playfully and tells the bemused medical team that she would like to get home to do the laundry.
For a woman who has been virtually moribund for 12 years, who has failed every known treatment for depression, from drugs to electroshock therapy, it is a sudden, striking transformation.
"It's almost as if someone turned Chantal back on," Ms. Remeny said of the experience. "It feels like the concrete was taken out of my head."
The procedure, known as deep brain stimulation, is still an experimental treatment, but one that is showing promising results.
"It's amazing that, with just a few volts of electricity, one can produce such striking change in someone's mood and behaviour," Dr. Lozano said.
Helen Mayberg, a neurologist at Toronto Western who is leading the research, is equally enthralled that such a simple surgery could deliver such results for patients deemed untreatable.
"To see profoundly ill people change before your eyes -- from the darkness and dullness to 'I feel like washing my clothes' is the most amazing feeling a doctor can have," Dr. Mayberg said.
TV viewers can witness that feeling themselves tonight: Ms. Remeny's surgery is featured on the CTV news show W-Five at 7 p.m.
Still, the scientists remain cautious in their optimism, noting that, to date, DBS has been used to treat only 16 people with severe depression. Ranging in age from 29 to 71, they are all Canadians. Eight of the first 12 have had positive results, and it's too early to see how the other four will fare.
But the real impact of the technique is that it is pushing scientists to rethink depression and how they treat mood disorders in general.
In recent decades, the focus has been on neurochemistry, using drugs such as Prozac to alleviate depression. Antidepressant drug therapy has been likened to "carpet bombing," affecting large portions of the brain, and it can have nasty side effects; besides, the drugs work only about half the time. The new approach is to target one specific node or pathway in the brain and treat it -- pharmacologically, surgically or electrically.
"The difference between this approach and the drug approach is when you give a drug to a patient, that drug has access to 100 billion neurons in the brain and has collateral effects on other neurons, other circuits," Dr. Lozano said.
"Now, we are pinpointing one small area of the brain, which is roughly one centimetre by one centimetre -- so just a few hundred thousand neurons -- and we can specifically target neurons causing trouble and make them behave in a more normal fashion."
With DBS, neurosurgeons target a region in the centre of the brain, known as cingulate area 25, which is linked to mood, especially sadness. In people with severe depression, that region is overactive -- like a thermostat stuck on a high setting -- and the electrical jolts are used to turn down the heat, and the sadness.
In other words, they have a pacemaker that regulates their level of depression. The hope is that other mood disorders can be similarly treated by targeting different areas of the brain. (In fact, DBS is also used as a treatment for Parkinson's disease but, in that case, electric currents target the hyperactive globus pallidus, an area of the brain crucial to movement.)
After publication of early results in the prestigious medical journal Neuron, neurosurgeons from around the world have been flocking to Toronto to learn the technique.
Dr. Sidney Kennedy, a psychiatrist who was part of the team that assessed Ms. Remeny to determine if she was a good candidate for surgery, said that DBS has the potential to change the way depression is defined and treated -- at least for a subset of patients. The research also helps demonstrate that there are likely many kinds of depression.
Dr. Kennedy said that when he first met Ms. Remeny he was struck by the "profound frozenness of her mood state" and he is awestruck by the change in her.
"The profound tense sadness, the sense of hopelessness, lack of energy, lack of interest. All of those things -- they are virtually all gone. It's absolutely amazing."
It must be stressed, however, that deep brain stimulation is not for everyone. An estimated one million Canadians suffer from some form of depressive illness, and as many as one in five have a chronic, unrelenting form of depression that does not respond to any treatment.
Surgery is also expensive, upward of $30,000 for each patient, and it entails risks. It can also take months to get the settings right so that depression is well-controlled.
One thing that is unclear is whether the treatment is permanent.
Rob Matte, a 39-year-old laboratory technologist from Toronto, had DBS surgery in August of 2004. A battery pack was sewn into his chest, and the wires run under his skin to the brain, so they are invisible.
He had struggled with depression for two decades, and his condition was worsening. Before the operation, he spent the better part of two years in bed and was suicidal.
"Look at me: I am alive," he said. Mr. Matte described the surgery as lifesaving, but he admitted that "part of me is just waiting for the bubble to burst."
He highly recommends the procedure to others struggling with severe, untreatable depression, but cautions that it is not a cure-all. "It's not like I don't still have bad days," Mr. Matte said. The difference is that he now has his regular ups-and-downs, and not depressive incidents that last weeks or months.
"I'm not a machine. I'm not happy all the time. No, I'm closer to normal."
Ms. Remeny, for her part, is enjoying her new-found normalcy. Upon her return from hospital, she did indeed do the laundry, and a lot of cleaning. She is looking forward to planting a garden, and is back on her motorbike.
Hope, once a distant memory, imbues her. "It feels like an incredible time in my life. I can't quantify it other than to say I am amazed at what the world feels like again."
And, with that, Ms. Remeny roared off. Not into the sunset. But into the hustle and bustle of daily life that she was so long deprived of by depression.