A breakthrough has been reported in the quality of mind-controlled artificial limbs.
According to a study in the Lancet medical journal, a paralysed woman has been able to pick up objects, move them and place them in precise locations using only a robotic hand - and her mind.
The woman, Jan Scheuermann, was 52 at the time of the study, and has been paralysed for years after being diagnosed with spinocerebellar degeneration.
Her robotic arm works by implanting two sensors - each about 4mm square - in the part of the brain that deals with movement, known as the motor cortex.
Each of the sensors holds about 100 needles, which are able to pick up information from 200 brain cells each.
The electrical pulses are translated into movements for the robotic arm to follow, and after training it appears that the woman could "routinely" use the arm to deftly use and manipulate objects.
"There is no limit now to decoding human motion," Michael Boninger, who worked on the study, told Reuters.
"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."
Bionic arms controlled by the mind have been available in varying forms since at least 2006, but the precision of the movements allowed have often been called into question.
The report said:
"The participant was able to move the prosthetic limb freely in the three-dimensional workspace on the second day of training. After 13 weeks, robust seven-dimensional movements were performed routinely. Mean success rate on target-based reaching tasks was 91.6%"
"The participant was also able to use the prosthetic limb to do skilful and coordinated reach and grasp movements that resulted in clinically significant gains in tests of upper limb function. No adverse events were reported."
The BBC quoted Professor Andrew Schwartz from the University of Pittsburgh as saying the results were "better than anything that's been demonstrated before".