Thursday, October 15, 1998 Published at 11:16 GMT 12:16 UK
Communicating with 'thought power'
Bionic brain implants allowing a computer to be operated by the power of thought, have been developed by American scientists.
Researchers at Emory University in Atlanta, Georgia, achieved the breakthrough by implanting hollow glass cone electrodes inside the brain's motor cortex - the part of the brain which controls movement - into which nerve cells grow and attach themselves.
Pointing the cursor at particular icons allowed them to communicate, making the computer voice phrases such as "I'm thirsty" or "please turn off the light".
The team hopes that as the technique is developed, the icons on the computer screen could perform more advanced functions, such as moving an artificial limb.
Simply by thinking of the movement, the computer could do what the body no longer can.
"It is going to take many more patients ... I don't think people should get their hopes up too high yet. I think it's going to take several years," he said.
Each implant consists of a hollow glass cone about the size of a ball-point pen tip.
Over several months, the implant becomes naturally 'wired' into the patient's brain as neurones grow into the cones and attach themselves to the electrodes mounted inside.
When the person thinks of an action which would normally occur through the nervous system, it is transmitted from the electrode to the computer.
An FM transmitter under the scalp transmits the signal without wires, and power induction means no batteries are needed.
"We transmit that out, process the signals, feed it back to the patient, so he can hear the activity, and also see the cursor move. So he is learning to move the cursor from one icon to the other," Dr Kennedy explained.
The first volunteer was a woman with Lou Gehrig's disease, a neurodegenerative condition that gradually robs victims of their ability to move.
She received the implants 18 months ago and has since died of her disease.
A second volunteer, a 57-year-old man almost totally paralysed by a stroke, received the implants six months ago.
The team has now been promised funding by the US National Institutes of Health to continue the research with three more patients.