Erik Sorto, who was paralyzed from the neck down after suffering a gunshot wound 13 years ago, became the first person in the world to have a neuroprosthetic device implanted in the posterior parietal cortex (PPC), which is an area of the brain where intentions are made.
Doctors at the University of Southern California’s Keck Hospital surgically implanted the new device in Sorto’s brain in April 2013. Since it was implanted in the area of the brain that controls the intent to move, the research team said that they were able to develop a way to move the robotic arm with more natural, smooth and fluid motions.
Most other neural prosthetic devices in use today are usually implanted in the motor cortex – the part of the brain that directly controls movement. As a result, these units tend to produce motion that doesn’t mimic natural movement but instead tends to be somewhat delayed and erratic.
“When you move your arm, you really don’t think about which muscles to activate and the details of the movement, such as lift the arm, extend the arm, grasp the cup, close the hand around the cup, and so on. Instead, you think about the goal of the movement. For example, ‘I want to pick up that cup of water,’” said Caltech’s Richard Andersen, the clinical trial’s principal investigator, in a press release.
The new device was clinically tested by its developers at Caltech – the California Institute of Technology – in Pasadena, California, along with their colleagues at the Keck School of Medicine at the University of Southern California, in Los Angeles and the Rancho Los Amigos National Rehabilitation Center in Downey, California.
“In this trial,” added Andersen, “we were successfully able to decode these actual intents by asking the subject to simply imagine the movement as a whole, rather than breaking it down into a myriad components.”
Since the surgery, researchers from Caltech and staff members at Rancho Los Amigos National Rehabilitation Center have been working to rehabilitate Sorto and teach him to control a computer cursor and a robotic arm with his mind.
Researchers and rehabilitation staff helped him develop the capability of performing a natural hand-shaking gesture with the robotic arm and even play the “rock, paper, and scissors” game with a separate robotic arm.
As his instruction and rehabilitation progressed, the researchers said that they were able to actually see what they were hoping for – the intuitive movement of the robotic arm.
Soto said he was surprised at just how easy it was to control the robotic arm.
Using his mind and the neural prosthetic to control a robotic arm, he said he was able to give himself a drink for the first time since becoming paralyzed.