New York, November 21
Speech sounds elicit comparable neural responses and stimulate the same region in the brains of humans, macaques and guinea pigs, study finds that could help pave the way for better understanding and diagnosis of auditory processing deficits .
A multidisciplinary group of researchers from the University of Pittsburgh reported in the journal eNeuro that the brain’s responses to sound – called frequency tracking responses, or FFRs – can be recorded from small electrodes placed on the scalp of one person.
They are used by clinicians to quickly assess a child’s hearing ability and flag a large number of potential speech and language disorders, such as dyslexia and autism. But the method has one major drawback – it lacks specificity.
“These tests can only tell us that something is wrong – but we don’t know what it is,” said Bharath Chandrasekaran, professor at Pitt’s School of Health and Rehabilitation Sciences. “Understanding the source and mechanism of FFR generation would allow the development of specific markers of speech disorders, which would help improve clinical diagnoses of auditory processing deficits,” he added.
FFRs are also used to identify any problems with auditory processing or how the brain interprets sounds from the environment, especially speech. The more the FFR profile resembles the profile of the sound source, the stronger the auditory processing capacity of the brain. On the other hand, the more the two profiles are different, the higher the chances of diagnosing a hearing loss.
Until recently, scientists believed that FFRs appear deep inside the brainstem – the brain’s innermost structures near the base of the skull – and spread outward, eventually reaching the surface of the brain and scalp.
Pitt’s researchers proved the long-held theory to be wrong when they discovered that FFRs are generated not only in the brainstem, but also in the auditory cortex of the brain – the region responsible for processing sound located just around the temple. , only one to a few centimeters from the surface of the skull – and that the pattern of FFR generation is similar in mammals.
In response to four different tones of the mandarin syllable ‘yi’, the brains of English speaking individuals unfamiliar with Mandarin Chinese generated FFRs similar to those of macaque monkeys and guinea pigs, both of which have hearing range. and a sensitivity very similar to humans.
A better understanding of how hearing deficits manifest in the brain may fill a critical gap in the development of rapid, accurate and non-invasive diagnoses, the researchers said. IANS