Washington: A 34-year-old paralysed man in the US is the first person in the world to have a neural prosthetic device implanted in a brain area that allows him to control a robotic arm with his intentions, scientists say.
Paralysed from the neck down after suffering a gunshot wound when he was 21, Erik G Sorto now can move a robotic arm just by thinking about it and using his imagination.
Neural prosthetic devices implanted in the brain's movement centre, the motor cortex, can allow patients with paralysis to control the movement of a robotic limb.
However, current neuroprosthetics produce motion that is delayed and jerky - not the smooth and seemingly automatic gestures associated with natural movement.
Now, by implanting neuroprosthetics in a part of the brain that controls not the movement directly but rather our intent to move, California Institute of Technology (Caltech) researchers have developed a way to produce more natural and fluid motions.
Researchers wanted to improve the versatility of movement that a neuroprosthetic can offer to patients by recording signals from a different brain region other than the motor cortex, the posterior parietal cortex (PPC), a high-level cognitive area.
The surgical team at University of Southern California (USC) performed the unprecedented neuroprosthetic implant in a five-hour surgery on April 17, 2013.
Neurosurgeon Charles Y Liu from USC and his team implanted a pair of small electrode arrays in two parts of the posterior parietal cortex, one that controls reach and another that controls grasp.
Each 4-by-4 millimetre array contains 96 active electrodes that, in turn, each record the activity of single neurons in the PPC.
The arrays are connected by a cable to a system of computers that process the signals, to decode the brain's intent and control output devices, such as a computer cursor and a robotic arm.
"The PPC is earlier in the pathway, so signals there are more related to movement planning - what you actually intend to do - rather than the details of the movement execution," principal investigator Richard Andersen from Caltech said.
Sixteen days after his implant surgery, Sorto began his training sessions at Rancho Los Amigos National Rehabilitation Centre, where a computer was attached directly to the ports extending from his skull, to communicate with his brain.
"It was a big surprise that the patient was able to control the limb on day one - the very first day he tried. This attests to how intuitive the control is when using PPC activity," Andersen added.
