by 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.