A MACHINE capable of deciphering people's thoughts could become a reality thanks to a breakthrough by US neuroscientists.

Researchers from the University of California-Berkeley developed a technique to record and decode patients' brainwaves and translate the electrical activity into words.

"This is huge for patients who have damage to their speech mechanisms because of a stroke or Lou Gehrig's disease and can't speak," Professor Robert Knight, coauthor of the study, said today. "If you could eventually reconstruct imagined conversations from brain activity, thousands of people could benefit."

The study involved 15 volunteers who were undergoing neurosurgical treatments for epilepsy or brain tumours. The Berkeley neurosurgeons placed electrodes in their temporal lobes to record activity and pinpoint the seizures.

They then recorded five to 10 minutes of conversation and used the data to reconstruct and play back the sounds the patients heard.

"There is some evidence that perception and imagery may be pretty similar in the brain," coauthor Dr Brian Pasley said. "If you can understand the relationship well enough between the brain recordings and sound, you could either synthesize the actual sound a person is thinking or just write out the words with a type of interface device."

As well as raising the hope of giving a voice to those who cannot speak, the researchers said that the study would advance understanding of how the brain represents and processes language.

"This research is a major step toward understanding what features of speech are represented in the human brain," Knight added.