US scientists spy on human minds with brain decoder

© Reuters / Michaela Rehle

Keeping your thoughts strictly to yourself may soon prove infeasible, with scientists working on a break-through, mind-reading device. The idea is to help people who are physically unable to interact with the outside world.

In fact, it's all about hearing "inner voices" and correctly interpreting them with the help of unique individual decoders, a researcher from the University of California, Berkley, explained.

"If you're reading text in a newspaper or a book, you hear a voice in your own head. We're trying to decode the brain activity related to that voice to create a medical prosthesis that can allow someone who is paralyzed or locked in to speak," Brian Pasley told magazine.

The team of researchers recorded brain activity in seven people undergoing epilepsy surgery, while they looked at a screen displaying texts from either one of the best-known speeches in US history: the Gettysburg Address by President Abraham Lincoln, or John F. Kennedy's inaugural address.

Each volunteer taking part in the experiment was asked to read their chosen text both aloud and silently. The challenge was to figure out which neurons reacted to specific aspects of speech in order to create a personalized decoder to turn this information into a visual representation.

Although the decoder was able to successfully reconstruct which words several of the volunteers were thinking, "it's not good enough yet to build a device," Stephanie Martin, who worked on the study with Pasley, told the magazine.

The researchers are currently sharpening the algorithms, scrutinizing the nuts and bolts of neural activity, especially the area concerned with speaking rate and different pronunciations of the same word.

The team is also trying to guess what a person is listening to by playing Pink Floyd songs to volunteers. "Sound is sound," Pasley wrapped up. "It all helps us understand different aspects of how the brain processes it."

In their previous study, when neuroscientists were hoping to produce sound from thoughts, they recorded brain activity in people who already had electrodes in their brain to treat epilepsy. They discovered that certain neurons in the brain's temporal lobe only responded actively to particular aspects of sound.

In 2011, Hollywood epics, such as , and , helped researchers from UC Berkeley monitor the blood flow in human brain with MRI scanners, and eventually recreate images similar to those being screened.