The power of mind over matter

Researchers in the US have developed a robotic arm controlled directly by thought with a level of agility closer than ever to a normal human limb.

These electrodes are remarkable devices in that they are very small

Jan Scheuermann, a 52-year-old woman who was diagnosed with a degenerative brain disorder 13 years ago and is paralysed from the neck down, was able to operate the robotic arm with a level of control and fluidity not seen before in this type of advanced prosthesis.

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, re-searchers 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 reawaken a person’s own paralysed muscles.

Meanwhile, they say, systems like this could be paired with robotic exoskeletons that allow paraplegics and quadraplegics to walk.

In the latest study, published in the Lancet, a research team from the University of Pittsburgh Medical Centre 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.

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.