Freeing a Trapped Mind
A year has passed since 16-year-old Heather Cole last heard her beloved grandfather John tell a joke or strum a tune on his guitar.
Struck by a heart attack and then a massive stroke, John (he asked that his last name not be used) awakened to find he couldn’t speak or move a muscle below his face. In medical terms, the 52-year-old drywall contractor was “locked in,” mentally alert but unable to communicate with the outside world.
Now, John’s mind has been released. Thanks to two Atlanta doctors--and a technological leap that may offer hope for millions of invalids--John’s brain does something no other brain has ever done: It controls the cursor of a computer. Like a mouse, his brain manipulates the cursor across the screen, making it possible for John to spell out words and activate icons that communicate basic needs.
“We’re just listening in, eavesdropping on the signals that he’s generating from his brain,” said Dr. Philip Kennedy, an Emory University neuroscientist.
In March of last year, two tiny electrodes developed by Kennedy were inserted into the motor cortex of John’s brain by Dr. Roy Bakay, an Emory neurosurgeon. Surrounding the electrodes are glass capsules the size of a ballpoint pen tip, each containing a nerve-growth stimulator.
Within weeks, nerve tissue began growing into the capsules, creating a bridge between the electrodes and John’s brain. As the nerve tissue grew, the electrodes picked up brain signals. The signals were transmitted through his skull to an antenna attached to a cap on his head (there are no wires protruding through the skin and no batteries). The antenna forwarded the signals to the computer.
On the computer screen, the cursor moves horizontally from left to right as John concentrates on moving his paralyzed right arm. (One of the electrodes is implanted in the area that controls right arm movement). When the cursor reaches a desired letter or icon, it stops. According to Kennedy, human brain signals have never before been recorded and transmitted “for so long and with such stability.”
German Team Doing Similar Therapy
In all, it is estimated that there are anywhere from half a million to more than 1 million locked-in patients--people who, because of disease or injury, can no longer control their muscles enough to speak or activate any communication device. They are trapped within themselves, unable to express their most basic desires or simplest wishes.
Like the Atlanta-based group, a team of neuroscientists at the University of Tuebingen in Germany recently reported that, after more than a year of intensive training, two patients paralyzed by advanced amyotrophic lateral sclerosis (ALS) learned to modulate their own brain waves to spell words on a computer screen.
After 150 training sessions, the two patients, who have not been able to breathe unaided for four years, now can write a short sentence in about 12 minutes by controlling the speed and rhythm of a characteristic brain wave.
“For the first time in history,” psychologist Niels Birbaaumer at Tuebingen reported at a recent meeting of the Society for Neuroscience, “the ability to communicate directly with one’s own brain is clearly documented and the possibility has opened up to escape--at least verbally--from the locked-in state.”
Although it is remarkable enough that these people can use mental self-control to move a computer cursor, Richard Andersen and his colleagues at Caltech hope to one day harness the brain’s power to activate artificial limbs and other prosthetic devices for the paralyzed that can be controlled by neural codes.
As a first step, they are implanting electrodes in the posterior parietal lobes of healthy monkeys and are starting to train them to move an object on a computer screen.
“Our hope is to have the patient interact with the world just by thinking about it,” Andersen said.
At Emory in Atlanta, the electrodes are the result of research begun 12 years ago by Kennedy at the Georgia Institute of Technology, also in Atlanta. Kennedy first studied his device on rats. After two years, he moved on to Emory’s Yerkes Primate Center, where he and Bakay experimented on monkeys.
Money for the project was scarce, but with support from Emory, they chose their first human patient, a woman suffering from ALS, or Lou Gehrig’s disease. Because of the severity of her condition, she was able to move only her eyes. She lived for 76 days after the implant surgery. During that time she learned to control her brain’s firing of signals as a step toward operating the computer.
Kennedy found John, a Vietnam veteran who was a patient at a local veterans hospital, very receptive to the idea of implant surgery.
The Veterans Administration agreed to underwrite some of the costs, and John fit the criteria mandated by the Food and Drug Administration: connected to a ventilator, fed through tubes and requiring constant care. And, most important, he was alert and intelligent.
“He is a very courageous man,” Kennedy said.
Last month, John took a major step in his training with the computer. Kennedy watched as John concentrated on the monitor at the end of his bed. The cursor moved across the keyboard pictured on the screen. One by one, the patient picked out the letters J-O-H-N. It was the first time he had spelled out his name. But that wasn’t enough. The cursor began moving again.
“I looked up and I saw a P, an H, and an I,” Kennedy said. “I said to my associate, ‘I don’t believe an L is coming up.’ ” It did. John had spelled the first four letters of his doctor’s first name.
During the past two weeks, Kennedy’s joy over John’s progress has been overshadowed by his patient’s worsening physical condition. The pain of bedsores has required the administration of analgesics. A side effect of the medication is lethargy. “I spent time with him on Monday,” Kennedy said. “He worked 10 minutes and fell asleep. It’s very discouraging.”
The doctors hope that John’s training will resume in a few months. They can foresee a time when he will be able to turn lights and TVs off and on, and ring for a nurse. He can already move the cursor to icons that read “I’m cold,” “I’m hot,” and his favorite, “See you later. Nice talking with you.”
Eventual Hope of Sending E-Mail
An Internet home page is planned where people can read about John’s condition. His doctors hope that as he learns more about controlling the firing signals of his brain, John will be able to type out e-mail messages. “A person can interact with the world if he can use a computer,” Bakay said.
Kennedy and Bakay recently won funding from the National Institutes of Health for a third implant patient. Ideally, this person will be someone in the early stages of Lou Gehrig’s disease who can still partially communicate with them.
“It is very difficult and very slow working with patients who cannot communicate,” Bakay said. “We can learn more about how to improve the use of the device by somebody who can give you a lot of feedback and information.”
In addition to the more than 700,000 Americans who suffer strokes each year, Kennedy estimates that about 3,000 people have Lou Gehrig’s disease.
Kennedy and Bakay look forward to a time when their work will go beyond helping patients communicate. They would like to see their implanted electrodes become control mechanisms for muscle stimulators.
“Our hope,” Bakay said, “is that soon we will be able to get to the point that we can connect the neural signals to a muscle stimulator in the patient’s paralyzed limb, and have them move that limb using the same principle that they use to move the cursor.”
Times science writer Robert Lee Hotz contributed to this story.
