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'Thought-Control' Prostheses - Soon a Reality
By Miki Fairley In the movie The Empire Strikes Back, hero and Jedi
knight Luke Skywalker found himself locked in mortal combat with
Darth Vader. Beaten and wounded, Luke was pressed back by the Dark
Lord. Suddenly, Vader's light saber sliced upwards, severing the
young Jedi's right hand - sending it and Skywalker's light saber
spinning into the abyss below. Luke survived and was fitted with a
prosthetic hand.
Detailing the drama, a website continues with a description of
Luke's prosthesis: "Luke's prosthetic hand took advantage of the
latest biomechanical technology to create a life-like appendage
that worked just as well as the original. The frame of the hand was
made up of artificial bones crossed with wires and connectors. The
prosthetic replacement joined to Luke's living tissue via a complex
synthenet neural interface, allowing the young Jedi to feel through
his mechanical hand. Finally, a layer of synth-flesh covered the
mechanisms within, making the hand appear completely organic on the
outside. The medical droid 2-1B fitted Luke's artificial hand, and
tested its effectiveness once in place. When pricked with a small
needle, each of Luke's mechanical fingers responded, and Luke
registered the pain. He found he could clench his fist, waggle his
fingers...just as well as he had always done. Though Luke initially
felt a throbbing sensation when he thought of the circumstances
which had necessitated his replacement hand, 2-1B assured him it
was only a phantom limb pain, and would soon ease."
For soldiers injured in nitty-gritty warfare here on
planet earth, a similar prosthetic hand may become a reality in as
soon as two years. This is the time frame planned for clinical
trials to begin on a brain-machine interface prosthetic hand,
according to 1st Lieutenant Joe Miller, CP, MEd, Medical
Service Corps, US Army Reserve. Miller is a clinical/research
prosthetist at the Armed Forces Amputee Patient Care Program at
Walter Reed Army Medical Center, Washington, DC.
A formidable array of brainpower from several disciplines,
including neurosurgeons, neurologists, theoretical physicists,
biocomputer scientists, mechanical engineers, informatics
specialists, and others, have been brought to bear on the
project.
A high-level meeting brought together personnel from the Amputee
Care Program, the Department of Defense (DoD) Advanced Research
Project Administration (DARPA), and the Telemedicine and Advanced
Tactical Research Center (TATRC) to structure a plan for developing
high-level brain-machine interfacing for the advancement of
prosthetics, commonly known as "thought-control" prosthetics,
Miller explains. "We are working with researchers who are engaged
in brain-machine interfacing on animals and a few things with
humans." Groundwork has already been laid with monkeys, who through
tiny probes inserted in their brains, have been able to move
robotic arms by thought.
Designing such advanced prosthetic technology requires a
complexity of effort. A separate group is researching materials,
such as special alloys being developed for the space industry, and
another group is working on prosthetic design, Miller says.
Different techniques of interfacing a thought-control prosthesis
are being studied. The challenge: the brain has to interface with
something and so does the prosthesis. At the moment, Miller can't
discuss specifics, but notes, "We're waiting for funding on sealing
projects."
Possibilities lie with "bioskins" that can actually have sensory
receptors in them, Miller says. "We are looking at coating the
prosthesis with receptor material that will provide feeling and
perception."
Miller continues, "The question now is whether we can tap into
the cortical part of the brain or the peripheral nerves. There is
no prosthetic device on the market that can do what we want to do.
There are some experimental prosthetic hands with multi-dexterous
fingers, but there is no way to control each of those fingers right
now - there is no brain or peripheral nerve interfacing.
"We now have to design a device that can do that function,"
Miller sums up.
Simultaneous Research
Simultaneous research is currently involving a group working on
actual devices, a group working on the brain-machine interface, and
another team working on integration of the system to the body.
Initial funding is currently about $25-30 million, with the Walter
Reed side of the project being headed by Col. Geoffery Ling,
MD.
"If we can use the brain, we eliminate a lot of the electronics,
and if we use synthetic muscles as actuators, we eliminate a lot of
the gears and motors, and it becomes a very lightweight
prosthesis," Miller adds.
A power source is vital, and the researchers are going beyond
batteries and studying alternate types of fuel sources. The
materials side of the project is looking at stabilized fuel cells
which are the size of a lighter or a CO2 cartridge. The
fuel being considered is a combination that includes liquid
hydrogen.
Research Categories
The Military Amputee Research Program at WRAMC basically has
four different classifications, Miller explains:
(1) database management and development;
(2) clinical management; (3)
rehabilitation strategies; and (4) neurological
studies. "When we call for requests for proposals, we ask for which
of these areas the researcher is requesting funding." Since there
also are prosthetic researchers in the Walter Reed O&P
facility, this group submits proposals of its own as well, Miller
said. Funding can be either intramural - from the DoD through the
Military Amputee Research Program - or extramural, with funding
from outside sources.
An example of extramural funding for a project with a primary
investigator outside the DoD would be developing a technologically
advanced component. Impact statements of patient involvement must
be submitted to prevent confounding effects on the outcomes.
The research at Walter Reed involves outcomes measurements,
specific prosthetic components, crossover designs and interrelated
reliability studies, measurements as to how patients are evaluated,
and physical therapy rehabilitation strategies, among other areas.
Miller adds, "We have a couple of studies working through the Human
Use Committee looking at how technologies affect the function of
the patient, more than looking at the specific socket or foot."
"Hardening" of prosthetic technologies is also part of the task:
locating and fixing problems such as a microprocessor emitting
signals that can be detected by the enemy; coping with the effects
of hard use, heat, and dirt on componentry, and other tasks to make
prosthetic componentry battle-ready.
Exciting Breakthrough
But it's the technological breakthrough of a thought-controlled
arm and hand that excites the imagination as to what possibilities
would then open up for upperlimb amputees. Both transhumeral and
transradial prostheses with a terminal device are being considered
- and even a shoulder disarticulation prosthesis may be possible,
Miller says. With brain-machine interface, he notes, "You move like
you normally do. You move your arm because you want to - you don't
think, 'Okay, now open hand to grasp cup, close hand on cup.' You
just do it."
He continues, "We're looking at different types of robotic
systems; we're looking at actuators that may or may not be
biosynthetic muscles; we're looking at materials milestones such as
carbon nanotubes [which can be 1/1,000 of the thickness of a human
hair]."
More powerful computers, more in-depth research on the brain and
nervous system, better power sources - all of these are
contributing to the complete package.
Farther down the road, although not yet in the works, is the
possibility of pseudo limb regeneration, with a prosthesis placed
inside the body and muscle and skin tissue re-grown around it,
Miller says.
"I'm on the team from the clinical end - what we need to do on a
day-to-day basis to work with our patients," Miller continues. "I'm
involved with component size, shape, function, repairs - what we
need to do to bring it out of the science lab and make it
applicable clinically."
Part of the program's mission is to develop new technology for
everyone, not just soldiers, he adds. This current research could
even in time help other disabled persons as well as amputees. "Once
you've mapped the brain and know how it interfaces with the body,
there could be other developments in that direction," he says, but
adds with a smile, "At this point, though, that's looking at a
bigger picture than we are."
Table Of Contents - May 2005
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