Language processing is not hardwired in the brain
People who are blind repurpose brain areas that are typically involved in vision to understand spoken language instead.
Scientists once thought that certain parts of the brain were hard-wired to process information from specific senses or to perform specific tasks. For example, some had concluded that language processing is built into certain parts of the brain, because the way the brain responds to language is remarkably similar in different people even from very early on in life. Yet other studies with individuals who were born blind emphasize that experience also shapes the way the brain works. In people who are born blind, parts of the brain that typically interpret visual information in sighted people are often put to other uses.
Now, van Ackeren et al. show that people who became blind early in life are able to repurpose parts of the brain that are more typically used for vision to understand spoken language instead. A technique called magnetoencephalography was used to map how different parts of the brain respond when both people with sight and those who are blind listen to recordings of someone talking. In some of the experiments, the speech was distorted, making it unintelligible. In both groups, areas of the brain known to process sound information showed patterns of activity that match the rhythms present in the speech. The group with blindness also showed similar activity in parts of the brain usually used to process visual information, and even more so when they were exposed to intelligible speech.
The experiments show that the brain efficiently reshapes to adapt to a world with no visual input. It may do this by making use of connections that already exist between the auditory and visual brain centers. For instance, very young children use these connections to link what they hear to the lip movements of adults. Future studies are needed to determine if individuals whose ability to see is restored would be able to process the visual information or if the adaptation of the visual processing parts of the brain to help understand speech would interfere with their sight.
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