Medical Research: Dual Adaptation In Deaf Brains

The brains of people who cannot hear adapt to process vision-based language, in addition to brain changes associated with the loss of auditory input.

The brains of Deaf people reorganize not only to compensate for the loss of hearing, but also to process language from visual stimuli sign language, according to a study published today (February 12) in Nature Communications. Despite this reorganization for interpreting visual language, however, language processing is still completed in the same brain region.



“The new paper really dissected the difference between hand movements being a visual stimulus, and cognitive components of language,” said Alex Meredith, a neurobiologist at Virginia Commonwealth University, who was not involved in the study.



The brain devotes different areas to interpreting various sensory stimuli, such as visual or auditory. When one sense is lost, the brain compensates by adapting to other stimuli, explained study author Velia Cardin of University College London and Linköping University in Sweden. In Deaf people, for example, “the part of the brain that before was doing audition adapts to be doing something else, which is vision and somatosensation,” she said. However, Deaf humans “don’t just have sensory deprivation,” she added they also have to learn to process a visual, rather than oral, language.



To untangle brain changes due to loss of auditory input from adaptations prompted by vision-based language, the researchers used functional MRI to look at brain activation in three groups of people: Deaf people who communicate through sign language, Deaf people who read lips but don’t understand sign language, and hearing people with no sign language experience.



The researchers showed the three groups videos of sign language and videos that held no linguistic content. The signing videos were designed to allow Cardin’s team to pinpoint which areas had reorganized to process vision-based language, as these areas would only activate in Deaf signers. In contrast, the language-free videos would allow the researchers to identify areas in Deaf brains that had adapted to the loss of auditory input, as these brain areas would activate in both Deaf groups, but not in the brains of hearing volunteers. ... Read more: http://www.the-scientist.com/?articles.view/articleNo/34363/title/Dual-Adaptation-in-Deaf-Brains/

Deaf People May Have Trouble Reading

VIDEO [CC] - A new reason for why the Deaf may have trouble reading, health report.



Deaf people may have no trouble communicating words through American Sign Language, or ASL. But studies of ASL users show that the average Deaf adult reads at the level of a nine-year-old. The explanation has always been that this is because they never learned to connect letters with sounds. But a recent study shows that Deaf readers are just like other people learning to read in a second language.

Linguist Jill Morford led the study. She says: "The assumption has always been that the problems with reading were educational issues with what's the right way to teach reading when you can't associate sounds with letters. But what we're finding is that all this time we've been ignoring the fact that they're actually learning a new language." Ms. Morford is a professor at the University of New Mexico and part of a research center at Gallaudet University in Washington.



Most students at Gallaudet are Deaf; the center studies how Deaf people learn and use language. Professor Morford says signers are like English learners whose first language uses a different alphabet. She says: "Anyone who has a first language that has a written system that's very different than English, like Arabic or Chinese or Russian, knows that learning to recognize and understand words in English is much more challenging than if you already speak a language that uses the same orthography. "The orthography is the written system and spelling of a language. Of course, with signers, their first language has no written system at all, just hand gestures.



Gallaudet professor Thomas Allen explains what effect this has on reading. He says: "There's a silent hearing going on ... when a hearing person reads a word. When a deaf person reads a word, there's not. They see the word and there's some kind of an orthographic representation.



And some of the research in our center has shown that when Deaf readers read an English word, it activates their sign representations of those words." Signers can face the same problems as other bilingual people. Their brains have to choose between two languages all the time. Take the words "paper" and "movie." Their spelling and meaning are not at all similar. But, as Professor Allen points out, the signs for them are. To make the sign for paper," he says, "you hold one hand flat and you just lightly tap it with a flat palm on the other hand, and you do that a couple times and that means paper." Movie is very similar, except the other hand "lightly moves back and forth as if it were a flickering image on a screen."



The study appears in the journal Cognition. For VOA Special English, I'm Alex Villareal. This is the VOA Special English Health Report, from http://voaspecialenglish.com.