A brain implant has allowed a paralysed American woman to take a sip of a coffee unaided for the first time in almost 15 years, by using her thoughts to control a robotic arm.

The 58-year-old, who lost the ability to speak or move her limbs following a stroke in 1996, learned to use the BrainGate system to make reach-and-grasp movements with a robotic arm, as part of a clinical trial.

"The smile on her face was a remarkable thing to see," the trial's lead investigator, Dr Leigh Hochberg, said.

"For all of us involved, we were encouraged that the research is making the kind of progress that we had all hoped.


"Years after the onset of paralysis, we found that it was still possible to record brain signals that carry multi-dimensional information about movement and that those signals could be used to move an external device," Dr Hochberg said.

A 66-year-old man, who has also been without speech or movement of his limbs since a stroke in 2006, was also able to control the robotic arm with his thoughts.

The findings of the trial has been published in a report in Nature today, and offers hope to people with tetraplegia.

"Although robotic reach and grasp actions were not as fast or accurate as those of an able-bodied person, our results demonstrate the feasibility for people with tetraplegia,
years after injury to the central nervous system, to recreate useful multidimensional control of complex devices directly from a small sample of neural signals," the report said.

However Dr Hochberg, an associate professor of engineering at Brown University in Providence, Rhode Island, and a critical care neurologist at Massachusetts General Hospital/Harvard Medical School in Boston, said the technology is years away from practical use. The trials were undertaken in controlled conditions in their homes with a technician present to calibrate the system, he said.

The BrainGate neural interface system consists of a sensor to monitor brain signals and computer software and hardware that turns these signals into digital commands for external devices. The sensor is a baby aspirin-sized square of silicon containing 100 hair-thin electrodes, which can record the activity of small groups of brain cells. It is implanted into the motor cortex, a part of the brain that directs movement.

Dr John Donoghue, who leads the development of BrainGate technology and is the director of the Institute for Brain Science at Brown University, said the woman's ability to use BrainGate was especially encouraging because her stroke occurred nearly 15 years ago and her sensor was implanted more than five years ago.

He said some researchers have wondered whether neurons in the motor cortex might die or stop generating meaningful signals after years of disuse. Researchers in the field have also worried that years after implantation, the sensor might break down and become less effective at enabling complex motor functions.

Dr Donoghue said it is not the first glimmer of hope offered to paralysed people. Previous trials have used the technology to point-and-click a computer cursor, which has been used for communication.

"This is another big jump forward to control the movements of a robotic arm in three-dimensional space. We're getting closer to restoring some level of everyday function to people with limb paralysis."