In a 2011 study, participants with electrodes in direct brain contact were able to move a cursor on a screen by simply thinking of vowel sounds. This technique is called functional magnetic resonance imaging, to track blood flow in the brain has shown promise for identifying which words or ideas someone may be thinking about. By studying patterns of blood flow related to particular images, Jack Gallant’s group at the University of California Berkeley showed in September that patterns can be used to guess images being thought of -recreating “movies in the mind”.
Brian Pasley of the University of California, Berkeley and a team of colleagues have taken that “stimulus reconstruction” work one step further. They focused on an area of the brain called the superior temporal gyrus, or STG, which is one of the “higher-order” brain regions that controls linguistic functions.
The team monitored the STG brain waves of 15 patients who were undergoing surgery for epilepsy or tumours, meanwhile the team was playing an audio of a number of different words and sentences on speakers. They used a computer model that helped map out which parts of the brain were firing at what rate, when different frequencies of sound were played. Patients were told words to think about, the team was able to guess which word the participants had chosen and were even able to reconstruct some of the words, turning the brain waves they saw back into sound on the basis of what the computer model suggested those waves meant.
“From a prosthetic view, people who have speech disorders… could possibly have a prosthetic device when they can’t speak but they can imagine what they want to say,” Prof Robert Knight of UC Berkeley, senior author of the study, explained.