Theneuroscientistsmight, in a not too distant day, be able to listen to the constant internal monologues that take place in our minds, or to hear the imaginary speech of a patient with a stroke or an inability to speak, according to a team of researchers from the University of California (USA).
In a study published in the journal ‘PLoS Biology’, scientists explain how they have achieveddeciphering electrical activity in a region of the human auditory system called the superior temporal gyrus(STG). And how, by analyzing the pattern of activity in the STG, they were able toreconstruct the words that the subjects heard in normal conversation.
“This research is based on the sounds a person actually hears, but to use this in a prosthesis, these principles must apply to someone who is imagining a speech,” notes first author Brian N. Pasley, a post-doctoral researcher at the University of California, Berkeley. Pasley tried two different methods to match spoken sounds to the activity pattern of the electrodes. The patients heard a single word and Pasley used two computational models to predict the word based on the electrode recordings; the better of the two methods was able to reproduce a sound quite close to the original word.
The ultimate aim of the study was to explorehow the human brain encodes speech, and determine which aspects of language are most important for understanding. “At some point, the brain has to extract auditory information from outside and map it into a word, since we can understand language and words regardless of how they sound,” explains Pasley, “The big question is, what is the most significant unit of speech, a syllable or a phoneme? “.
This study could be crucial for patients with impaired speech mechanisms from stroke or Lou Gehrig’s disease, for example.
