iNDICA NEWS BUREAU-
Humans and monkeys do not have a lot of differences. Now another study proves that a monkey’s brain, macaques to be specific, receives and stimulates the neural responses of speech sounds similar to the brains of humans.
In research led by an Indian American professor from the University of Pittsburgh, reported that the brain’s responses to sound — called frequency-following responses, or FFRs — can be recorded from small electrodes placed onto a person’s scalp.
Bharath Chandrasekaran, Professor at Pitt’s School of Health and Rehabilitation Sciences, being a multidisciplinary group said that these findings can help clinicians to quickly assess a child’s hearing capacity and flag a slew of potential speech and language disorders, such as dyslexia and autism. But the method has a major drawback – it is lacking specificity.
“Understanding the source and mechanism of FFR generation would allow for the development of specific markers of speech impairments, which would be instrumental in improving clinical diagnostics of auditory processing deficits,” Chandrasekaran said
“These tests can only tell us that something is off – but we don’t know what that ‘off’ is,” he added.
The FFRs which show up on a neurotypical brain electroencephalogram as a near carbon copy of the sound wave that the brain is interpreting and responding to—have the potential to complement hearing screening of newborns.
If the baby’s brain produces an electrical response to a sound played though tiny headphones, then the neural pathway connecting the ear to the high-level information-processing center in the brain cortex is developed and functional.
The FFRs are also used to identify any issues in auditory processing, or the way that the brain interprets sounds coming from the environment, especially speech.
The closer the FFR profile resembles the profile of the sound source, the stronger the brain’s auditory processing capacity. In contrast, the more different the two profiles are, the higher the chances of diagnosing an auditory deficit.
Until recently, scientists thought that FFRs arise deep inside the brain stem and ripple outward, eventually reaching the surface of the brain and the scalp. This study proves the long-standing theory wrong as they found that FFRs are generated not only at the brain stem, but also in the auditory cortex of the brain — the region responsible for the processing of sounds located right around the temple, only a few centimeters away from the surface of the skull — and that the pattern of FFR generation is similar across mammals.
In response to four different tones of the Mandarin syllable “yi”, the brains of English-speaking individuals who aren’t familiar with Mandarin Chinese generated similar FFRs as macaque monkeys and guinea pigs, both of which have very similar hearing range and sensitivity to humans.
Between 5% and 10% of Americans have been diagnosed with communication disorders, researchers say.
A better understanding of the way auditory deficits manifest in the brain can fill a critical gap in the development of fast, accurate and non-invasive diagnostics, the researchers said.
“Recognizing the similarities between animal and human FFRs will allow us to study neural circuitry of sound processing in much greater detail,” said lead author Nike Gnanateja Gurindapalli, Ph.D., a postdoctoral fellow at Pitt.
“These explorations will further pave the way for new models of auditory processing in both typical and impaired auditory systems, which can eventually be used to infer auditory deficits using simple and effective non-invasive tools in the clinic.”
