Thursday, Mar 23rd

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Last December, Jan Scheuermann ate a piece of chocolate. It was a feat that earned her a round of applause. Lots of people eat chocolate, especially around the holidays. What was so special about this particular chocolate-eating experience? Jan Scheuermann, a quadriplegic for nine years, fed the chocolate to herself using a mind-controlled robot arm.

Scheuermann's ability to feed herself that piece of chocolate was the culmination of research conducted at the University of Pittsburgh Medical Center (UPMC) using brain-computer interface (BCI) technology along with training programs that allow a quadriplegic to perform some of the everyday movements we all take for granted. It was a collaborative effort involving a group of researchers. One of these researchers, Dr. Elizabeth Tyler-Kabara, noted that the idea of creating a thought-controlled robot arm originated over ten years ago. It began with studies using animal subjects to learn how neurons represent signals for motor control allowing an animal to perform specific movements.

Monkeys were the final animal subjects to test the possibilities of this new technology prior to human testing. Dr. Tyler-Kabara explains, “If you look at the musculature of the hand and arms, it is quite similar to humans. How the (monkey) brain is controlling movements and how the animal is making movements – it is almost a one-to-one correlation between shoulder movement, elbow movement, and finger movement.” Monkeys had another distinct advantage over other animal species – they were intelligent enough to be trained. Learning to use the robot arm required extended training, making “the primate model one of the favored models,” according to Dr. Tyler-Kabara.

Choosing Jan Scheuermann to road test the arm was also based on a certain characteristic she possessed. The basic question that needed to be answered before selecting her as a candidate was, “If she imagined a motion, was there activation in the cortex?” This is the part of the brain commonly called the gray matter. Here, a huge network of neurons allows humans to think, move and speak. What the researchers were looking for was whether or not Scheuermann's brain tried to do what she imagined she was doing.

The only way to answer that question was to test. Scheuermann was given a functional MRI – a test that measures brain activity through changes in the amount of blood flow. Scheuermann's MRI indicated that when she imagined a movement, there was activity in the cortex. The next test was a magnetoencephalogram, which Dr. Tyler-Kabara describes as “a very, very fancy EEG coupled to an MRI. If electrical activity occurs, it will pick it up.” This test also indicated activity in the cortex. The researchers determined that the structure of Scheuermann's cortex was normal and capable of exactly the kind of activation they were seeking.

After passing the tests to confirm she was a viable candidate, Dr. Tyler-Kabara implanted two quarter-inch square electrode grids with 96 contact points in the areas of Scheuermann’s brain that control right arm and hand movement. These contact points register signals from individual neurons and the signals are fed into a computer algorithm to identify how the brain creates a movement like raising an arm. The two grids were left protruding from Scheuermann’s skull so they could be hooked up to the computer. Within a week after beginning training, Scheuermann could manipulate the robot arm to reach in and out, left and right, and up and down. In less than three months, she could flex the wrist, move it from side to side and rotate it. Scheuermann could also use the hand to grip objects.

The robot arm used in this research was developed at Johns Hopkins University's Applied Physics Lab through a program called Revolutionizing Prostheses. This program was launched in 2006 by the Defense Advanced Research Projects Agency (DARPA) to encourage the design and development of prostheses to replace non-functioning arms. At that time, the types of prosthetic devices available for arms were far less advanced than those used to replace non-functioning legs.

The big question now is – when will this technology be available as a mainstream therapy? Dr. Tyler-Kabara said that there are some hurdles that have to be overcome first. The device implanted in the brain has to be small enough to be fully implanted instead of “having cables sticking out of the head.” That obstacle is already being successfully addressed.

An even greater obstacle, however, according to Dr. Tyler-Kabara, is convincing insurance companies and Medicare/Medicaid that this is a viable therapy with enough merit so that they will be willing to pay for it. Researchers are already coming up with new metrics to show how this thought-controlled limb will improve a recipient’s quality of life, making each one a more productive member of society. If all of this behind-the-scenes effort goes well, the thought-controlled robot arm could become available in as little as five years.



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