Nineteen blind children lay in a fMRI scanner and listened to stories, music, or someone speaking a foreign language such as Russian, Hebrew or Korean. As they listened to the stories, something unexpected happened — the visual cortex lit up.
A control group of 40 sighted children, even those who were blindfolded, did not have the same brain response.
Johns Hopkins cognitive neuroscientist Marina Bedny, one of the researchers who conducted the experiment while at the Massachusetts Institute of Technology, concluded that the brain is far more flexible than previously thought and that the blind children's visual cortex was involved in processing language. Her study was published in August in The Journal of Neuroscience.
"Studying this particular phenomenon gives us insight into how far the brain can stretch," she said. "It pushes this idea that the brain can do anything."
The phenomenon of the visual cortex responding to language has previously been documented in adults, but Bedny said it never before had been studied in children.
The adult response had been thought to be the result of learning Braille, but some of the children in Bedny's study, who ranged in age from 4 to 17, were too young to have learned Braille. Yet even the 4-year-olds had a fully formed ability to use their visual cortex to process language.
Their visual cortex responded to speech, music and foreign languages, but lit up the most in response to hearing stories they understood.
Previous research also documented similar brain rewiring in the deaf, and Bedny said her research attempted to probe questions of how much of the brain is shaped by nature and how much by nurture. In the future, Bedny said, she wants to explore whether the phenomenon occurs in people who have become blind in adulthood, rather than at birth.
But what it means that the visual cortex helps process language in the blind remains unclear, Bedny said. Some studies have documented that blind people have somewhat enhanced hearing abilities, but it's not yet known if that is a result of their experience and practice at paying attention to sounds.
The notion that the blind have super-powered hearing is a "myth," said Chris Danielsen, a spokesman for the National Federation of the Blind, which is based in Federal Hill. The idea has persisted in the era of gifted blind musicians like Stevie Wonder and Ray Charles, who lost their sight as children.
"As blind people we tend to pay more attention to sound, we analyze it more than the average sighted person does and use it to learn things about our environment," he said. "That would perhaps be the reason for the reallocation of the brain's resources, rather than just sort of let the visual cortex lie fallow, it's using it for input that it can process."
More recently while at Johns Hopkins, Bedny has documented that the visual cortex in blind adults responds to complex sentences but not to math equations read aloud. That research has been accepted by the same Journal of Neuroscience and is set to be published this month. In that study, Bedny relied on the help of blind adults at the National Federation of the Blind.
Bedny's research seemed to make sense on a layman's level, Danielsen said.
"My unscientific guess would be what's happening is that, because the brain is not getting input visually, it's simply reallocating resources toward the input that it is getting," he said.
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Though many sighted people have had the experience of visualizing a story they are told as well, the visual cortex did not have the same response in the sighted children. And for the blind children, the visual cortex responded the same whether the sentence they heard in a story was in active voice or passive voice.
Bedny said the assumption that Braille was responsible for causing the visual cortex to respond to language in the blind may be due to the tendency for the sighted to make conclusions based on how they think their own brain would respond.
"One of the things I've learned is that sighted people think the most difficult thing about being blind is being blind," she said. "But really it's dealing with the misconceptions, the social stigma."
Bedny immigrated to the United States from the Ukraine in the former Soviet Union at age 11, and she said she lost her accent while her parents kept theirs.
"It got me interested in that question of how does experience change how our mind works," she said.