MIND
March 25, 2011

The Brain As Executive Recruiter

Brain scans show how the visual cortex of blind people is recruited by the brain to help them process language.

In recent years, more evidence has come in to suggest that the brain is actually much more plastic – or changeable – than previously thought. Different brain areas step in and pick up functions normally covered by other areas if those areas are damaged. Even though various parts of brain are generally pretty specialized for certain tasks, new research shows that the brains of blind people may actually be able to redistribute functions.

This suggests that the brain is much more plastic than previously thought, and that when areas are not needed for one function (such as vision) they can be recruited for other functions to serve the individual better.

A new study found further evidence for the idea that the visual cortex of the brain is capable of processing language in intricate ways.

The researchers in the current study wanted to see how the visual cortices of blind people responded when processing spoken language. They scanned the participants’ brains with functional magnetic resonance imaging (fMRI) while they listened to sentences. The researchers found that the visual cortex was indeed reacting to word meaning and sentence structure in the same way that the normal language areas of the brain do. This is particularly striking since researchers used to think that the areas of the brain that process and produce language were too specialized to have their function replicated by other parts.

Study author Marina Bedny, PhD, Research Fellow in Neurology at Boston's Beth Israel Deaconess Medical Center says in a press release that the findings "suggests that a part of the brain can participate in language processing without having evolved to do so." But she admits that the results are exciting: "The idea that these brain regions could go from vision to language is just crazy. It suggests that the intrinsic function of a brain area is constrained only loosely, and that experience can have really a big impact on the function of a piece of brain tissue."

Other recent research has found that visual areas of the brain in blind people can be used to process auditory-spatial information much in the way that visual-spatial information is processed in sighted people. This suggests that the brain is much more plastic than previously thought, and that when areas are not needed for one function (such as vision) they can be recruited for other functions to serve the individual better. Bedny explains that "[a]s 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".

The team is currently planning future studies to determine whether blind people may actually be better at processing auditory information than sighted people, and at what age the visual parts of the brain switch over to language processing.

The study was carried out by researchers at MIT and Harvard University, and published in the February 28, 2011 online issue of Proceedings of the National Academy of Sciences.

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