A multidisciplinary group of researchers at the University of Pittsburgh just published a study in the journal eNeuro that suggests that monkeys, guinea pigs and native English speakers have similar brain responses to speech sounds .
The brain’s responses to sound, called frequency tracking responses, or FFRs, can be recorded from tiny electrodes placed on a person’s scalp.
Diagnosis for hearing
The finding could help pave the way for a better understanding and diagnosis of auditory processing deficits. And it is that doctors use FFR to quickly assess a child’s hearing ability and point out a large number of possible speech and language disorders, such as dyslexia and autism. But the method has a major drawback: it lacks specificity .
Understanding the source and mechanism of FFR generation would allow the development of specific markers of speech disturbances, which would be essential to improve the clinical diagnosis of auditory processing deficits.
The more closely the FFR profile resembles the profile of the sound source, the stronger the brain’s auditory processing ability. On the contrary, the more different the two profiles are, the greater the chances of diagnosing a hearing impairment.
By combining EEG recordings of the scalp with recordings of electrodes placed inside the skull, the researchers discovered that FFRs are generated not only in the brainstem, but also in the auditory cortex of the brain, the region responsible for processing sounds located around it. from the temple , just a few centimeters from the surface of the skull, and that the FFR generation pattern is similar in all mammals.
In response to four different tones of the Mandarin syllable "yi", the brains of English speakers unfamiliar with Mandarin Chinese generated FFRs similar to those of macaque monkeys and guinea pigs, which have a range hearing and sensitivity very similar to humans .