Bedny notes that the research does not refute the idea that the human brain needs Broca's and Wernicke's areas for language. "We haven't shown that every possible part of language can be supported by this part of the brain [the visual cortex]. It just suggests that a part of the brain can participate in language processing without having evolved to do so," she says.
One unanswered question is why the visual cortex would be recruited for language processing, when the language processing areas of blind people already function normally. According to Bedny, it may be the result of a natural redistribution of tasks during brain development.
"As these brain functions are getting parceled out, the visual cortex isn't getting its typical function, which is to do vision. And so it enters this competitive game of who's going to do what. The whole developmental dynamic has changed," she says.
This study, combined with other studies of blind people, suggest that different parts of the visual cortex get divvied up for different functions during development, Bedny says. A subset of (left-brain) visual areas appears to be involved in language, including the left primary visual cortex.
It's possible that this redistribution gives blind people an advantage in language processing. The researchers are planning follow-up work in which they will study whether blind people perform better than sighted people in complex language tasks such as parsing complicated sentences or performing language tests while being distracted.
The researchers are also working to pinpoint more precisely the visual cortex's role in language processing, and they are studying blind children to figure out when during development the visual cortex starts proces
|Contact: Caroline McCall|
Massachusetts Institute of Technology