Researchers develop robot arm controlled by thought

Researchers in the US have developed a robot arm controlled by the power of thought. It significantly raises hopes that paralysed patients might soon direct artificial limbs using nothing more than their imagination.

The scientists studied the activity of circuits inside the brain of a monkey as it moved its arm when reaching for food. They developed a powerful computer programme that could interpret what the firing of these circuits meant and then mimic the motion, using a robotic limb.

The computer instantaneously matched the monkey's movement simply by reading what its brain was doing. To further demonstrate the system's effectiveness it used the Internet to direct another robot hundreds of miles away, with this robot also imitating the monkey's hand and arm in real time as it moved about.

Teams from Duke University, North Carolina, the State University of New York and the Massachusetts Institute of Technology (MIT) collaborated on the remarkable achievement, which is described today in the science journal, Nature.

"The idea of driving robotic limbs with what effectively amounts to the mere power of thought was once in the realm of science fiction. But this goal is edging closer to reality," Dr Sandro Mussa-Ivaldi, of Northwestern University Medical School, Illinois, and the Rehabilitation Institute of Chicago, stated.

The team implanted very fine "microwires" in the brains of two owl monkeys so they could watch the reactions of large groups of brain cells called neurons. They studied how the neuron groups responded when the monkeys made three-dimensional hand movements as they reached for food on a tray.

They then used an advanced computer called a neural network and complex software "to predict hand position in real time", the researchers reported. The software was able to predict the monkey's intended movement by interpreting its neuron response and then mimic the motion with a nearby robot arm at Duke and one operating several hundred miles away at MIT.

The implanted wires operated reliably for at least two years, the researchers said. "In this context, our findings support the notion that motor signals derived from ensembles of cortical neurons could be used for long-term control of prosthetic limb movements," they stated.

The use of denser wires with implantable microchips "could one day form the basis of a brainmachine interface for allowing paralysed patients to control voluntarily the movements of prosthetic limbs."