'Inner voices': US scientists spy on human minds with brain decoder
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 New Scientist 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 Madagascar 2, Pink Panther 2 and Star Trek, helped researchers from UC Berkeley monitor the blood flow in human brain with MRI scanners, and eventually recreate images similar to those being screened.