“We want to galvanize people’s imaginations,” said Miguel Nicolelis, the Brazilian neuroscientist at Duke University who is leading the Walk Again Project’s efforts to create a robotic suit that could one day ‘make wheelchairs obsolete’.
Mind-controlled leg armor may sound like science fiction. But after decades of testing on rats and monkeys, neuro prosthetics are finally beginning to show promise for people. Devices plugged directly into the brain seem capable of restoring some self-reliance to stroke victims, car crash survivors, injured soldiers and others hampered by incapacitated or missing limbs.
Nicolelis is a pioneer in the field. In the 1990s, he helped build the first mind-controlled arm. Rats learned they could manipulate the device to get a drink of water simply by thinking about doing so.
Researchers studied the signals as the rats pushed a lever to guide the arm that gave them water, and they saw groups of neurons firing at different rates as the rats moved the lever in different directions. An algorithm was developed to decipher the patterns, discern the animal’s intention at any given moment and send commands from the brain directly to the arm instead of to the lever. Eventually, rats could move the arm without pushing the lever at all.
Using similar brain-machine interfaces, Nicolelis and his team learned to translate the neural signals in primate brains. In 2000, they reported that an owl monkey connected to the Internet had controlled an arm located 1,000 km away. Eight years later, the team described a rhesus monkey that was able to dictate the pace of a robot jogging on a treadmill half a world away in Japan.
Small groups of neurons, it seemed, were surprisingly capable of communicating with digital devices. Individual cells learn to communicate with computer algorithms more effectively over time by changing their firing patterns, as revealed in a study of a mouse’s brain published last year in Nature. “You can count on this plasticity when designing a prosthetic,” said Jose Carmena, a neuroscientist at the University of California at Berkeley. “You can count on the brain to learn.”
Capitalizing on that adaptability, several human quadriplegics have received implanted brain chips in FDA-approved clinical trials. In a widely publicized demonstration of that system, a 58-year-old woman paralyzed by a stroke sipped a cup of coffee last year using a five-fingered robotic arm, not attached to her body. Despite the slickness of the presentation, however, the woman actually had little control over the aesthetically pleasing arm. Her thoughts triggered preset choreography. “What she was controlling was really simplistic, really rudimentary,” said Andrew Schwartz, a neuroscientist at the University of Pittsburgh.
His team’s robotic arm offers much more freedom, as well as greater agility and speed. Funded in part by the U.S. military and built at the university, the freestanding mechanical limb sports a wrist that bends and rotates. Jan Scheuermann, a 53-year-old with a rare degenerative disorder, named the arm “Hector” and learned in a single day to move it around like a claw in an arcade game. After 13 weeks of training, she mastered the fine control needed to grasp objects and stack cones. Fulfilling a long-standing goal, she fed herself a chocolate bar — and followed it with some string cheese and a red pepper.
To achieve this dexterity, Schwartz’s team had implanted two chips in Scheuermann’s brain instead of the usual one. The duo monitored about 200 neurons at once, more than ever before. More neurons communicate more information, helping to clarify the brain’s desires.
But even hundreds of cells may not be enough to allow someone to control two mechanical limbs at once — a device that scientists hope to showcase at the upcoming World Cup. “You really need to reach thousands of neurons,” said Nicolelis. That is why his team is developing a new kind of electrode that branches like a tree, covering a larger volume of the brain. Made of a flexible plastic that conducts electricity, the electrode can monitor nearly 2,000 brain cells in a mouse.
Nicolelis’s dream is for the very first kick of the 2014 FIFA World Cup in Sao Paulo next June to be delivered by a Brazilian teenager who is paralyzed from the waist down. If all goes according to plan, the teenager will walk onto the field, cock back a foot and swing at the soccer ball using a mechanical exoskeleton controlled by the teen’s brain.
Motorized metal braces will support and bend the kicker’s legs. The braces will be stabilized by gyroscopes and powered by a battery carried by the kicker in a backpack. German-made sensors will relay a feeling of pressure when each foot touches the ground. And months of training on a virtual-reality simulator will have prepared the teenager to do all this using a device that translates his or her thoughts into actions.
The blueprints for next summer’s soccer exoskeleton also include sensors that will provide an artificial skin for its human wearer. With the world watching, Nicolelis hopes not only that his bionic teenager will be able to feel the ball but also that disabled people everywhere will feel a sense of hope.
Source: The Washington Post
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