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Disability in the News.

Brain implants give the paralyzed a voice.

Warren King, Seattle Times medical reporter

Scientists have developed an electronic device that when implanted in the brain allows severely impaired patients to "will" a computer to speak for them. It may someday help them move limbs and other body parts.

Called a neurotrophic electrode, the device harnesses brain cells' electric impulses to move a computer cursor, which in turn activates spoken words or phrases.

"This is right on the cutting edge. It's `Star Wars' stuff. . . . We see it as replacement therapy for whatever has caused a (physical) loss," said Emory University scientist Dr. Roy Bakay, who was presenting his research today to the Congress of Neurological Surgeons. More than 2,000 neurosurgeons are attending the meeting in Seattle this week.

Bakay, vice chairman of the neurosurgery department at Emory University, said the technology, called cognitive engineering, could someday be used to help paralyzed patients move limbs or prosthetic devices. For now, it is being tested in patients with the most severe impairments, including the inability to speak and move their eyes.

More than 700,000 Americans a year suffer strokes and thousands more are impaired from spinal-cord injuries and illnesses such as Lou Gehrig's disease. Most can think quite clearly, but many are severely hampered by their inability to communicate adequately.

Bakay and his Emory colleague, Dr. Philip Kennedy, conducted extensive research on monkeys before their first human experiments. The system they devised uses a combination of the brain's most basic functions and space-age electronics.

Implants work with `smart cap'

Before the device is implanted, physicians first examine the brain through magnetic-resonance imaging (MRI) to learn precisely the areas that control muscle movements. When the patient thinks about moving an arm or hand, for example, the MRI shows the increased activity in certain areas: blood flow increases and the brain cells "fire," or conduct impulses.

The key device in the system is the neurotrophic electrode, a glass cone about the size of a ballpoint-pen tip that is implanted through the skull and into the cortex just above the ear. Two electrodes are implanted to facilitate vertical and horizontal movements of the cursor.

The cone contains a gold wire and nerve tissue from the leg. Nerve cells inside the cone stimulate cells of the cortex to grow into the device and form contacts. The wire records the impulses between the cells.

"It produces a little brain inside the electrode," Bakay said.

Once the implant is made, the skull is closed and no wires go through it. A receiver and amplifier for each implant sit in slight indentations in the top of the skull. A signal processor filters the correct signals for the patient to move the cursor. The system is powered by a baseball-cap-sized, removable induction coil called a "smart cap" that sits on top of the head.

When the system is turned on, the patient listens to the firing of the brain cells, called neurons. The activity sounds like a beehive; when the patient thinks about movement, the buzzing becomes faster and louder.

The patient learns to control the level of the neuron firing with his thoughts about different movements. It is a far more complex system than the computers that read the eye movements of paralyzed patients.

Thoughts move computer cursor

The Emory University scientists and patients have learned through trial and error how to tailor thoughts of movement for each patient. For example, thinking about moving the hand and foot may make the cursor move up and down for one patient.

"At first it was difficult to stop the cursor on the speech icon, so we had to reprogram the system," said Bakay, who has been working on the project for more than eight years.

Pointing to different icons produce phrases such as "I am thirsty" and "turn the light on" and "see you later. Nice talking to you."

Two patients have had the implants. The first was a 52-year-old woman who eventually died of Lou Gehrig's disease (amyotrophic lateral sclerosis). "She really wanted to do this and we learned a lot about the basic principles of this from her," Bakay said.

The scientists are now working with a 57-year-old man, a stroke victim who is paralyzed from the neck down.

Bakay said the research was so futuristic that he couldn't secure the usual government funding at first; he got money instead from Emory University and the Department of Veterans Affairs. After he and his colleagues proved the system viable, he received a research grant from the National Institutes of Health for research with three more patients.

Cognitive engineering has potential for helping many different kinds of patients, Bakay said. These include trauma victims who have lost limbs and cancer patients who have lost their voices. As the technology improves, controlling movement or speaking will become more and more automatic for patients, he said.

"We hope that it can really improve people's lives," Bakay said.  
 

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