The neural architecture in the auditory cortex - the part of the brain that processes sound - of profoundly deaf and hearing people is virtually identical, a new study has found.
The study raises a host of new questions about the role of experience in processing sensory information, and could point the way toward potential new avenues for intervention in deafness. The study is described in a June 18 paper published in Scientific Reports.
The paper was authored by Ella Striem-Amit, a post-doctoral researcher in Alfonso Caramazza's Cognitive Neuropsychology Laboratory at Harvard, Mario Belledonne from Harvard, Jorge Almeida from the University of Coimbra, Quanjing Chen, Yuxing Fang, Zaizhu Han and Yanchao Bi from Beijing Normal University.
"One reason this is interesting is because we don't know what causes the brain to organize the way it does," said Striem-Amit, the lead author of the study.
"How important is each person's experience for their brain development? In audition, a lot is known about (how it works) in hearing people, and in animals... but we don't know whether the same organization is retained in congenitally deaf people."
Those similarities between deaf and hearing brain architecture, Striem-Amit said, suggest that the organization of the auditory cortex doesn't critically depend on experience, but is likely based on innate factors. So in a person who is born deaf, the brain is still organized in the same manner. But that's not to suggest experience plays no role in processing sensory information.
Evidence from other studies have shown that cochlear implants are far more successful when implanted in toddlers and young children, Striem-Amit said, suggesting that without sensory input during key periods of brain plasticity in early life, the brain may not process information appropriately.