Healthy living

Scientists decode brain waves

Scientists decode brain waves Electrical signals 'translated' into sound

Scientists have taken the first step towards reading someone's mind, by linking brain waves to individual spoken words, a study shows.

In the future the method could be used to hear the imagined speech of a patient unable to speak due to stroke or paralysis, researchers at the University of California, Berkeley said.

For the study, the scientists enlisted the help of 15 epilepsy patient volunteers. The patients were undergoing neurosurgery, which involved having electrodes placed on their brains to try to pinpoint the source of their intractable seizures.

During surgery, the scientists read various words and sentences to the patients, while the brain activity detected by the electrodes was recorded onto a computer.

The researchers were most interested in the brain activity in a particular region known as the superior temporal gyrus, which is know to be involved in processing sound.

Using a computer model, they were able to map the brain activity patterns to the different frequencies of sound in the speech heard by the patients.

The researchers were then able to predict what words patients heard based on brain activity patterns alone. They even reconstructed some of the words using the computer model to "translate" the brain patterns back into sound.

"There is some evidence that hearing the sound and imagining the sound activate similar areas of the brain, said study co-author Dr Brian Pasley, a neuroscientist at the Helen Wills Neuroscience Institute.

"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."

Robert Knight, a professor of psychology and neuroscience at the university, added: "This research is a major step toward understanding what features of speech are represented in the human brain.

"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. If you could eventually reconstruct imagined conversations from brain activity, thousands of people could benefit."

The study is published in the journal PLoS Biology.

This article was published on Wed 1 February 2012

Image © Adeen Flinker, UC Berkeley

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