SAO PAULO (Reuters) - Scientists believe they are a step closer to enabling paralyzed people to walk and use artificial arms after an experiment in which monkeys moved and sensed objects using only their minds.

The monkeys were able to operate a virtual arm to search for objects through brain activity that was picked up by implants -- a so-called brain-machine interface.

In a leap forward from previous studies, the primates were also able to experience the sense of touch -- a crucial element of any solution for paralyzed people because it enables them to judge the strength used to grasp and control objects.

"This was one of the most difficult steps and the fact that we achieved it opens the door to the dream of a person being able to walk again," Miguel Nicolelis, a Brazilian neuroscientist who took part in the study carried out by a team at Duke University in North Carolina.

The results suggest it would be possible to create a kind of robotic "exoskeleton" that people could use to feel and sense objects, he said.

"The success we've had with primates makes us believe that humans could perform the same tasks much more easily in the future," Nicolelis said.

The study was published in the journal Nature on Wednesday.

In the first part of the experiment, the rhesus monkeys were rewarded with food for using their hands to control a joystick in search of objects on a computer screen.

The joystick was then disconnected, leaving the monkeys to control the movement of a virtual arm on the screen through brain power alone.

Nicolelis told Reuters his goal is to use the technology to enable a young paraplegic athlete to take part in the opening ceremony of the 2014 soccer World Cup in Brazil.

From 2012, Nicolelis said the study will be taken over by Brazil and carried out at the Neuroscience Institute in the northeastern state of Natal.

(Writing by Stuart Grudgings: Editing by Alonso Soto and Paul Simao)

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