United States researchers have developed a mind-controlled robotic arm that has the level of agility closer than ever to a normal human limb.
The team of researchers from the University of Pittsburgh School of Medicine and UPMC have been working with Jan Scheuermann, who was diagnosed with a degenerative brain disorder 13 years ago and is paralysed from the neck down.
Using the robotic arm, she has been able to reach out and 'high five' someone, grasp and move objects of different shapes and sizes, and even feed herself dark chocolate. The team says accomplishing these seemingly ordinary tasks has demonstrated for the first time that a person with longstanding quadriplegia can manoeuvre a mind-controlled, human-like robot arm in seven dimensions (7D) to consistently perform many of the natural and complex motions of everyday life.
The research, published in the Lancet, implanted two microelectrode devices into the woman's left motor cortex, the part of the brain that initiates movement.
The medics used a real-time brain scanning technique called functional magnetic resonance imaging to find the exact part of the brain that lit up after the patient was asked to think about moving her now unresponsive arms.
The electrodes were connected to the robotic hand via a computer running a complex algorithm to translate the signals that mimics the way an unimpaired brain controls healthy limbs.
"These electrodes are remarkable devices in that they are very small," Michael Boninger, who worked on the study, said. "You can't buy them in Radio Shack."
But Boninger said the way the algorithm operates is the main advance. Accurately translating brain signals has been one of the biggest challenges in mind-controlled prosthetics.
"There is no limit now to decoding human motion," he said. "It gets more complex when you work on parts like the hand, but I think that, once you can tap into desired motion in the brain, then how that motion is effected has a wide range of possibilities."
It took weeks of training for Scheuermann to master control of the hand, but she was able to move it after two days, and over time she completed tasks – such as picking up objects, orientating them, and moving them to a target position – with a 91.6 per cent success rate. Her speed increased with practice.
The researchers plan to incorporate wireless technology to remove the need for a wired connection between the patient's head and the prosthesis. They also believe a sensory loop could be added that gives feedback to the brain, allowing the user to tell the difference between hot and cold, or smooth and rough surfaces.
Experts are calling it a remarkable step forward for prosthetics controlled directly by the brain. Other systems have already allowed paralysed patients to type or write in freehand simply by thinking about the letters they want. And in the last month, researchers in Switzerland used electrodes implanted directly on the retina to enable a blind patient to read.
The development of brain-machine interfaces is moving quickly and scientists predict the technology could eventually be used to bypass nerve damage and re-awaken a person's own paralysed muscles.
In the meantime, they say, systems like this could be paired with robotic 'exoskeletons' that allow paraplegics and quadraplegics to walk.
"This bioinspired brain-machine interface is a remarkable technological and biomedical achievement," said Grégoire Courtine at the Swiss Federal Institute of Technology in Lausanne, who was not involved in the study.
"Though plenty of challenges lie ahead, these sorts of systems are rapidly approaching the point of clinical fruition," Courtine said in a comment piece in the Lancet linked to the study.