Think and it's done

By Duncan Graham-Rowe
From New Scientist, 17 October 1998

Brain implants are making it possible for severely disabled people to use the
power of thought to communicate through a computer. The researchers
responsible hope that the technology will eventually allow people who are
totally paralysed to operate artificial limbs.

So far, two incapacitated people have received the implants. This gave them
the power to control a cursor on a computer screen by thinking about moving
parts of their body. By pointing the cursor at different icons, the patients
could make the computer voice phrases such as "I'm thirsty" or "Please turn
off the light".

"If you can run a computer, you can talk to the world," says Roy Bakay of
Emory University in Atlanta, Georgia, whose team developed the implants.

The implants consist of two hollow glass cones, no bigger than the tip of a
ballpoint pen, placed into the brain's motor cortex, which controls body
movements. The glass cones are laced with neurotrophic chemicals extracted
from the patients' own knees. These chemicals encourage nerve growth so, over
several months, neurons in the cortex grow pathways into the cones and attach
themselves to tiny electrodes mounted inside.

To decide where to place the implants, Bakay and his colleagues used a
magnetic resonance imaging scanner to reveal the most active regions of each
patient's motor cortex. Once nerves had grown into the cones, the patients
were asked to think about moving various parts of their body. The responses of
the electrodes in the cones were monitored and translated into commands for
the computer cursor.

At the moment these commands are quite simple: up and down for one cone, and
left and right for the other. But this is just the start, says Bakay.

Depending on exactly which nerves grow into the cones, each patient may have
to think about moving a different part of his or her body to achieve the
desired cursor movement. They are trained to use the device by listening to a
buzzer which becomes faster and louder when they are thinking along the right
lines. Controlling the cursor soon becomes second nature, says Bakay.

The implants are powered by a coil worn outside the skull in a cap. This
induces a small current in a transmitter-receiver placed just inside the
skull. It transmits to an amplifier in the cap, which boosts the signal and
sends it to the computer.

It has taken the researchers eight years to come this far. After extensive
research on monkeys they were given permission by the US Food and Drug
Administration to try the procedure on up to three human subjects.

The first volunteer was a woman with Lou Gehrig's disease, or amyotrophic
lateral sclerosis, a neurodegenerative condition which gradually robs its
victims of their ability to move. She received the implants 18 months ago and
has since died of her disease.

Six months ago a 57-year-old man, almost totally paralysed by a stroke, became
the second to receive the implants, Bakay told the Congress of Neurological
Surgeons in Seattle last week.

The team has now been given funding by the National Institutes of Health to
continue the research with a further three patients.

"If these implants can be developed then they could do an enormous amount to
alleviate many illnesses," says John Cavanagh of the International Spinal
Research Trust in Cheshunt, Hertfordshire.

Bakay is confident of making progress but warns that it may be several years
before the implants can be used to give more complex commands.

Copyright New Scientist, RBI Limited 1998

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