11/27/2000

By Sue Goetinck Ambrose / The Dallas Morning News

Many ailments that impair the body's motion – ranging from writer's cramp to

weakness after stroke – aren't just physical. Nor are they just in the mind.

They may, however, be in the brain.

Scientists have discovered that many physical problems are "learned" by the brain. Writers and musicians with useless hands have found relief in the form of "unlearning" exercises that rewire the brain's circuitry. Stroke victims have regained use of hands and legs after years of immobility. And researchers wonder whether similar brain-based treatments will help people with autism, cerebral palsy, chronic pain and certain repetitive strain injuries.

"I do think the field of rehabilitation is on the verge of a revolution," said Edward Taub, a neuroscientist at the University of Alabama at Birmingham.

Traditionally, the field of physical therapy has focused on the mechanics of a disability, said Nancy Byl, professor of physical therapy and rehabilitation science at the University of California, San Francisco. A new appreciation of the brain's role may change that.

"You can treat muscular imbalance, alignment problems and all the mechanical events, but you've got to consider the whole person and how the problem is being stored in the nervous system," Dr. Byl said. "We have such an incredible opportunity ... to take what we learn in neuroscience and apply it to physical therapy."

Neuroscientists know that the brain continually remodels itself based on its "owner's" experiences. In someone who types or plays piano many hours a day, the brain forms a precise internal map of the hand in which each finger is distinct. But someone who writes with a pencil all day – with the fingers held as a unit – may develop a brain map in which the fingers overlap.

You can see this for yourself, said Thomas Elbert, a neuroscientist at the University of Konstanz in Germany. Have a friend touch a toe and, without looking, try to guess which one was touched. Most people will have trouble, Dr. Elbert said. Because the toes move together every day, the brain's toe map is blurred.

Remodeling can occur quickly. One study by Alabama's Dr. Taub found that a man's finger map changed after the middle and ring fingers on one hand were amputated. Brain cells that normally contained the map for those two fingers contained the map for the remaining index and pinky fingers just 10 days after the amputation.

While brain remodeling is often useful – helping a budding musician find guitar strings, for instance – remodeling can also be a curse.

"You learn to do things right, and you learn to do things wrong," Dr. Byl said.

Studies by Dr. Byl, Dr. Elbert and Michael Merzenich, also of UCSF, have suggested that writer's or musician's cramp, technically known as focal hand dystonia, is actually the result of learning gone wrong.

A person with focal hand dystonia can have trouble moving fingers separately. The fingers may curl up, and some pianists, for instance, can play only with their knuckles. Therapies include medications or injections of botulinum toxin to relax the muscles. But there is no reliable cure.

Dr. Merzenich said he believes relearning is the key.

"You have to learn your way out of this disability, because you learned your way into it," he said.

Gripping a pen or pencil tightly for hours at a time "teaches" the brain that the fingers are not distinct. Playing a piano piece where the fingers move up and down too rapidly teaches the same lesson. Eventually, the brain loses the ability to control the digits separately, and the hand cramps.

Studies by Drs. Elbert and Byl, presented this month in New Orleans at the annual meeting of the Society for Neuroscience, showed that simple training exercises can change the brain's maps of the hand. Dr. Byl's dystonia patients practiced Braille, matched tiny plastic animals simply by feeling them, and had to guess what shapes were being drawn on their hands. Dr. Elbert's 11 patients, all musicians, wore splints on their good fingers and practiced repetitive movements with the bad fingers, an hour a day for a year. Eventually, three of the musicians were able to perform in concert again.

Brain imaging, Dr. Elbert said, shows that the musician's brains really did relearn how to use the fingers better. Before the therapy began, all the fingers occupied the same spot on the brain's map. After therapy, each finger had a distinct spot in the brain.

Brain maps can also change after a stroke. In monkeys given strokes that decrease the use of a hand, brain maps change, said Randolph Nudo, a neuroscientist at the University of Kansas Medical Center in Kansas City. Dr. Nudo has found that the part of the brain usually devoted to controlling the hand is recruited into controlling the elbow and shoulder. But given rehabilitation therapy, the monkeys' brain maps return to normal.

To retrain the monkeys, Dr. Nudo and his colleagues outfitted the animals with a jacket that prevented movement of the good arm. This tricked the monkeys into using their bad arms.

Researchers have applied the same ideas to people who have suffered strokes. Traditionally, stroke patients are told they will recover on their own for up to a year. After that, doctors generally believe, there is no further improvement.

But Dr. Taub has found that people who had strokes as long as 20 years earlier can regain movement in their hands or legs.

After a stroke, many patients try to speak or move and are unsuccessful. They quickly stop trying, Dr. Taub said. With one paralyzed hand, for example, a stroke patient may use the other hand more. As a result, more brain space becomes devoted to the good hand. A vicious spiral ensues.

But the spiral can be reversed when patients are forced to do what they've come to believe they can't, Dr. Taub said.

Restraining the good hand, for instance, in what is called constraint-induced movement therapy, forces people to use their bad hand. Patients undergo intensive training, working six hours a day for two or three weeks. The restraint is worn for 90 percent of waking hours. Traditional physical therapy involves only a few half-hour or hour sessions per week, Dr. Taub said.

With the hand restrained, patients may be asked to throw balls, push brooms, move checkers, draw or work with building blocks. The better they get, the more they want to try. After training, patients report better use of their hands in daily life, Dr. Taub said.

And a research article of Dr. Taub's, published recently in the journal Stroke, showed that the therapy really does remodel the brain. Brain mapping studies before the therapy began revealed a shrunken map of paralyzed hands of 13 stroke patients who had suffered strokes an average of four years earlier. Following 12 days of constraint-induced therapy, the maps had expanded.

In addition to restoring movements to hands, Dr. Taub has had success improving mobility of legs. He has also been able to help people with an inability to come up with the words they want, a language difficulty called expressive aphasia.

Researchers believe many other physical conditions have a root in a miswired brain. Scientists are investigating whether autism and cerebral palsy, for instance, may be partly "learned" by the brain. Some studies have hinted that chronic back pain may be partly a learned phenomenon. And researchers believe many repetitive strain injuries that plague typists or assembly-line workers may have similar roots in the brain.

If that's the case, Dr. Byl said, current efforts to combat repetitive strain injuries in the workplace may need to be revamped.