London: Scientists have successfully taught monkeys to move the arms of a computer game character using power of thought alone, a breakthrough they say could benefit severely paralysed patients.

A team at the Duke University Centre for Neuroengineering in Durham, the US, taught two rhesus monkeys to operate a virtual arm with their brain power. The animals were able to differentiate between the textures of virtual objects they were "feeling".

The researchers hoped that their findings could pave the way for the development of a "robotic exoskeleton" to be worn by severely paralysed people, helping them move and experience the world around them using brainwaves, a newspaper reported.

"Someday in the near future, quadriplegic patients will take advantage of this technology not only to move their arms and hands and to walk again, but also to sense the texture of objects placed in their hands," Professor Miguel Nicolelis, who led the study, said.

The electrical brain activity of the two rhesus monkeys trained at the centre was used to direct the hands of a virtual monkey shown on a screen -- without them moving any part of their real bodies.

The virtual hands were then used to explore the surface of three virtual objects, which looked the same but had been designed to have different textures, which were expressed as tiny electrical signals sent back to the monkeys' brains.

In the task, the monkeys had to search for a virtual object with a particular texture and were rewarded with fruit juice if they correctly identified it.

The study, published in the journal Nature, was the first to show that the brain controlling a virtual arm that explores objects while the brain simultaneously receives electrical feedback signals that describe the fine texture of objects "touched" by the monkey's newly acquired virtual hand.

Prof Nicolelis said: "Such an interaction between the brain and a virtual avatar was totally independent of the animal's real body, because the animals did not move their real arms and hands, nor did they use their real skin to touch the objects and identify their texture.

"It's almost like creating a new sensory channel through which the brain can resume processing information that cannot reach it anymore through the real body and peripheral nerves."

One of the monkeys needed only four attempts before it learned to select the correct object in the test, while the other took nine attempts.

"The remarkable success with non-human primates is what makes us believe that humans could accomplish the same task much more easily in the near future," Prof Nicolelis added.

The Walk Again Project, led by the Duke Centre for Neuroengineering, wants to carry out a public demonstration of a robotic exoskeleton, which could allow quadriplegic people to move again, at the opening game of the 2014 Football World Cup in Brazil.