Sat, 16 Mar 2002 20:46:27 -0600
[more on using the brain to mouse a computer cursor, plus other details on
the company exploring this. still trying to understand the basics of sensory
conditions. e.g. a blind person 'seeing' with an electrode tongue implant...]
Implanted electrodes could aid paralyzed patients.
By Rebecca Zacks April 2002
/image caption/ Cyberkinetics uses brain signals picked up by this
four-millimeter-square array of electrodes to control a computer or a
robotic arm. (Image by Furnald/Gray)
In a small lab at Brown University in Providence, RI, a rhesus
macaque sits in a chair facing a computer screen, gripping the handle
of a device that looks a lot like a sailboat's tiller. For the
moment, the monkey uses this device as if it were a computer joystick
to control a simple video game: a colored dot appears on the screen,
and the animal moves the cursor to meet it. Once the animal gets good
at the task, though, the researchers in the adjoining room will flip
a switch and it will be signals straight from the monkey's brain, not
the joystick's movements, that drive the cursor.
This eerie feat is possible because the researchers, led by Brown
neuroscientist John Donoghue, have implanted a tiny array of
electrodes in the monkey's brain. The electrodes intercept signals
from individual neurons in the brain, and a specially developed
computer algorithm translates these signals into trajectories and
velocities for the computer cursor. The researchers' ambitions,
however, extend way beyond video-game-playing monkeys. Their hope is
that their brain-machine interface system will give patients
paralyzed by spinal-cord injuries or neurodegenerative diseases new
abilities to interact with the world around them-using nothing more
than the power of their thoughts.
Donoghue and his team launched Cyberkinetics in June 2001 to pursue
that vision. The company is one of the first to arise from research
into brain-machine interfaces, which has so far been relegated mainly
to a handful of academic labs around the world (see "Brain-Machine
Interfaces," TR January/February 2001).
http://www.techreview.com/articles/tr10_nicolelis0101.asp And while
much development remains to be done, a system like Cyberkinetics'
that taps directly into the brain could theoretically give paralyzed
patients the means to control computers, robotic aids-and perhaps
even their own muscles. Cyberkinetics aims to begin testing that
theory in humans by the end of this year.
In the monkey studies that will pave the way for the human tests, the
company-which includes cofounders Nicholas Hatsopoulos of the
University of Chicago, Brown MD/PhD student Mijail Serruya and
Gerhard Friehs, a neurosurgeon at Providence's Rhode Island
Hospital-is focusing on the area of the brain that issues commands to
the monkey's arm. Friehs starts by implanting a
four-millimeter-square array of 100 electrodes in this region, which
is located in the brain's outermost layer, about halfway between the
ear and the top of the skull. After the surgery, a small bundle of
wires snakes from the array through a hole in the animal's skull;
those wires are plugged into a computer, feeding the electrical
signals generated by neurons firing near each electrode into the
Hatsopoulos sits at that computer as the plugged-in monkey practices
a video game in the next room. The brain activity picked up by the
array flashes across the screen as a jumble of hyperkinetic EKG-like
graphs; rendered audible by the computer's speakers, brain signals
snap, crackle and pop like Rice Krispies in milk. Hatsopoulos turns
up the volume. "I never get tired of listening to that," he says.
"This is really like reading the mind, eavesdropping on cells in the
brain as the monkey's thinking of something." Pattern recognition
software fishes the signal "spikes"-each representing a single firing
of a single neuron-from the brain's background noise and correlates
them with the position of the monkey's arm. "The amazing thing," says
Donoghue, "is that very quickly you can get a sense of the neurons'
activity and extract the hand's trajectory." Indeed, using only three
minutes or so of data from the video game exercise, the computer can
build a model capable of extrapolating the monkey's arm movements
from the brain signal alone. Once the model is fine-tuned, the
computer can use the brain signal to drive either a cursor or a
robotic arm in real time.
Such promising results are part of what inspired the researchers to
launch Cyberkinetics and push toward clinical trials. "We already
know so much; now let's put it to use," says Serruya. The
participants in Cyberkinetics' first human tests will be "locked-in"
patients who, due to injury, stroke or neurological disease, are
completely paralyzed, unable even to communicate except via subtle
movements of their eyes. In those initial trials, the company will
implant the electrode array, manufactured by Salt Lake City, UT-based
Bionic Technologies, but the signal-processing hardware and power
supply will remain outside of the body. If those first human tests
bear out the promise of the monkey experiments, the company plans to
further develop the technology to create an entirely implantable
To date, only one company has conducted human tests of a
brain-recording implant with the aim of helping restore function in
paralyzed patients: Atlanta, GA-based Neural Signals. Instead of an
electrode array, the company implants two "neurotrophic
electrodes"-glass tubes containing tiny wires and a substance that
encourages brain cells to grow into the devices. Neurologist and
Neural Signals founder Philip Kennedy says the studies, begun in
1997, are going more slowly than he had originally hoped, but that
the company should have some clear results by the end of the year.
Cyberkinetics researchers believe, however, that implanting 100
electrodes instead of just two will make their system more robust and
will allow it to gather more information from the brain.
While recent work in brain-machine interfaces is encouraging, some
significant hurdles remain, says William Heetderks, head of the
National Institutes of Health's Neural Prosthesis Program, which
helps fund brain-machine interface research. Perhaps the biggest
challenge, Heetderks says, is building an interface between the
recording device (a rigid piece of hardware) and the brain (a squishy
mass floating in cerebrospinal fluid) that will maintain its precise
position for decades, despite small movements of the brain. While
both Kennedy's and Donoghue's devices represent progress on that
front-Kennedy's by encouraging cells to grow into the device and
stabilize the connection, Donoghue's by gripping the brain much as
golf cleats grip wet earth-Heetderks thinks that some combination of
approaches might ultimately be necessary. At this point, Heetderks
says, human studies "may be still a little bit premature. But
obviously that's just one opinion."
Greg Licholai, director of ventures and business development for the
neurological division of Minneapolis, MN-based Medtronic, offers a
different view. "This is truly a breakthrough in approaching
neurological disorders," Licholai says of Donoghue's efforts. "I
don't think there's going to be a problem recruiting patients, and
the system has been well proven in an animal model. The only
potential holdup is how long it takes them to draw up the documents
and get FDA approval of those early-stage trials."
Cyberkinetics' business manager and only employee, Brown
undergraduate Mikhail Shapiro, is helping the company look for the
management team and funding it will need to get that paperwork in
order and the human tests under way. Shapiro and the company's
founders all realize they will face both business and technological
challenges, but they are also convinced that, as Hatsopoulos puts it,
"This is real. This is really going to help people."
Rebecca Zacks is a senior associate editor at Technology Review.
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electromagnetism / infrastructure / civilization