Now, a computer programme that can write our thoughts

In a discovery that could provide a new form of communication to millions of people suffering from paralysis or neurological diseases, American scientists have developed a technique that allows users to write numbers and characters on the screen just by thinking.

While demonstrating their technique, the neuroscientists at the Mayo Clinic campus in Jacksonville, Florida, said brain waves can be used to type alphanumerical characters on a computer screen.

They said paralytic patients could make letters appear on screen just by focusing on that letter when presented with a matrix of symbols.

"This study constitutes a baby step on the road toward that future, but it represents tangible progress in using brain waves to do certain tasks," said neurologist Jerry Shih, the lead author of the study.

The findings, presented at the 2009 annual meeting of the American Epilepsy Society, represent concrete progress toward a mind-machine interface that may, one day, help people with a variety of disorders control devices, such as prosthetic arms and legs.

These disorders include Lou Gehrig's disease and spinal cord injuries, among many others, The Science Daily reported.

The study saw two patients have electrodes placed inside their skulls and directly on to the surface of the brain through a surgical incision known as a craniotomy. These electrodes then monitored electrical activity produced by firing nerve cells.

The signals produced when the patients looked at specific figures on a six-by-six grid were then interpreted by a computer running the researchers software.

When a patient focused on a letter, it appeared on screen The technique, known as electrocorticography, produces better data than the more commonly-used electroencephalography, in which the electrodes are placed on the scalp.

"There is a big difference in the quality of information you get from ECoG compared to EEG. The scalp and bony skull diffuses and distorts the signal, rather like how the Earth's atmosphere blurs the light from stars," said Dr Shih.

"That's why progress to date on developing these kind of mind interfaces has been slow." Once the technique is perfected, its use will require patients to have a craniotomy, although it isn't yet known how many electrodes would have to be implanted. And software would have to calibrate each person's brain waves to the action that is desired, such as movement of a prosthetic arm, Dr Shih said.

"These patients would have to use a computer to interpret their brain waves, but these devices are getting so small, there is a possibility that they could be implanted at some point," he added.