1999 Discover Awards
July, 1999 - page 88
Assistive Technologies

Winner

Wiring the Mind

Each year thousands of people become prisoners in their own bodies when
paralyzed by stroke, disease, or injury. Philip Kennedy believes hes found a
way to free these victims of "locked-in syndrome."  The key is what he calls
a neurotrophic electrode - a hollow glass cone filled with recording wires
and chemicals that promote nerve growth. When the electrode is placed in the
motor cortex of the brain and hooked to a computer, it allows a patient to
move a cursor across a computer screen, putting him or her once again in
touch with the outside world. 

The growth-inducing chemicals in the tip of the glass cone beckon the brains
cells into the electrode, where they link up with the recording wires. "I
realized that to generate an electrode to be stable over the lifetime of the
patient." Kennedy explains, "we need the brain to connect into the electrode,
instead of trying to get the electrode into the brain."  

Once the link is made, electrical activity in the implanted area of the brain
is picked up by the wires and transmitted to a receiver and amplifier. The
patient can learn to control these signals and use them, like a mouse, to
move a cursor. A biofeedback system generates noises that "indicate when the
brain is thinking in a way that will allow a person to focus on the cursor,"
Kennedy says. 

His first subject, a woman suffering from amyotrophic lateral sclerosis (the
same disease that afflicts physicist Stephen Hawking), learned to turn the
signal on and off but died from her disease shortly thereafter. This year,
Kennedy and neurosurgeon Roy Bakay implanted electrodes in another subject -
a 53-year-old man who had suffered a stroke in the brain stem. He is now able
to move the cursor horizontally across the screen and pick out icons that
prompt the computer to speak commonly used phrases. 

Soon Kennedy hopes to use signals from neurotrophic electrodes to control
electrical stimulators attached to a patients paralyzed muscles, bypassing
the signal block created by spinal cord injury. In addition, he notes, the
electrode can be used to study brain function. "Never before," he says, "have
recordings been made from a human brain for so long and with such stability
of the recorded signals."

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Finalists

Invisible Touch
Innovator: John Sabolich
Sabolich Research and Development

Prosthetics can restore some of the mechanical abilities of a missing limb
but none of its sensations. Lack of feeling condemns the wearer to a life of
uncertainty: Is the ground too uneven for safe walking? Is the baby's bath
water warm and not scalding hot? 

John Sabolich, a second-generation prosthesis engineer, created the Sabolich
Sense of Feel System and Hot & Cold Sensory System to help put such questions
to rest. 

The Sense of Feel System "reads" the ground using pressure sensors implanted
in a prosthetic foot. The sensors transmit information to the electrodes
pressing against the base of the residual limb. The electrodes in turn
stimulate the nerve endings in the skin; the greater the pressure on the
sensors, the more intense the stimulus. At first the signal feels like a
tingle, but soon the brain learns to interpret it as pressure. Eventually,
Sabolich says, some prosthesis wearers begin to experience the sensations as
if they were coming from the lost foot. 

The Hot & Cold Sensory System works in much the same way, using temperature
sensors in place of pressure sensors. Thermal readings from the sensors are
used to heat or cool a plate pressed against the skin, so the amputee can
easily interpret the signal. 

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Manual Miracle
Innovator: William Craelius
Rutgers University

When Jay Schiller lost his hand in an accident, even the simplest manual task
became frustrating. But last year he sat down at the piano and played "Mary
Had a Little Lamb," nimbly moving one artificial finger at a time. 

It was a proud moment for William Craelius, inventor of the tendon-activated
pneumatic artificial hand that made Schiller's performance possible. The hand
has a plastic socket that encases an amputee's upper limb. Sensors in the
socket respond to movements of the remaining tendons in the limb. The device
relies on a sort of muscular memory: the wearer moves the prosthetic fingers
by activating the same tendons originally used to move the real fingers. When
it picks up a tendon twitch, a limb sensor signals a computer activator to
move part of the hand.  

"For most subjects," says Craelius, "the training is simple. They simply
command a particular finger to move. The sensor detects the command, the
computer decodes it, and the finger moves."  

