Scientists are to implant tiny computer chips in the brains of paralysed patients which could 'read their thoughts'.
The chip contains tiny spikes which will extend into the brain
US researchers from Cyberkinetics Inc are to be allowed to implant the chips underneath the skulls of patients.
The chips will map the neural activity which occurs when someone thinks about moving a limb.
Scientists will then translate those signals into computer code that could one day be fed into robotic limbs.
The company, based in Foxboro, Massachusetts, has been given Food and Drug Administration approval to begin the trials of the four-millimetre square chips.
The 'Brain Gate' contains tiny spikes that will extend down about one millimetre into the brain after being implanted beneath the skull, monitoring the activity from a small group of neurons.
The signals will be monitored through wires emerging from the skull, which presents some danger of infection. The company is working on a wireless version.
It is hoped the research - which until now has been carried out on animals - could eventually help patients who have been paralysed by strokes or diseases such as cerebral palsy.
While people may survive with many years with these conditions, their quality of life can be poor.
Other researchers have carried out work aimed at deciphering how the brain sends signals to make limbs move.
In 1998, researchers found a brain implant allowed a paralysed stroke victim move a cursor to point out
phrases on a computer screen.
The next year, other scientists said
electrodes on the scalps of two Lou Gehrig's disease, a motor neurone disease, allowed them to spell messages on a computer screen.
Cyberkinetics has previously carried out animal research where three monkeys were given implants.
These were used to record signals from their motor cortex - an area of the brain that controls movement - as they manipulated a joystick with their hands.
Those signals were then used to develop a programme that enabled one of the monkeys to continue moving a computer cursor with its brain.
The company believes it is the first to implant a sophisticated device inside human's brains.
It hopes to complete the research within three to five years.
'The right time'
Patients will be asked to imagine carrying out a particular movement, such as moving their hand a few inches.
Researchers will then try to identify the brain
activity associated with that desire
This could then one day be fed into devices such as a robotic arms, that could help patients act on that desire.
Moving the experiment from monkeys to humans is a
But Richard Andersen, an expert from the California Institute of Technology, who is carrying out similar
research, said the field was advanced enough to warrant this next step.
He said: "I think there is a consensus among many researchers that the time is right to begin trials in humans."
He said surgeons were already implanting devices
into human brains - sometimes deeply - to treat deafness and Parkinson's disease
"There is always some risk but one considers the benefits."
Dr Richard Apps, a neurophysiologist from Bristol University, told BBC News Online: "There have been some real advances in being able to do this kind of work in animals.
"The next step is trying to work out what computer coding to replicate the complex neural signals needed to direct limbs to move."
But he added: "This research is an encouraging step."