Wednesday, August 31, 2011

Localizing Language in the Brain: Study Pinpoints Areas of the Brain Used Exclusively for Language

New research from MIT suggests that there are parts of our brain dedicated to language and only language, a finding that marks a major advance in the search for brain regions specialized for sophisticated mental functions.

Functional specificity, as it's known to cognitive scientists, refers to the idea that discrete parts of the brain handle distinct tasks. Scientists have long known that functional specificity exists in certain domains: In the motor system, for example, there is one patch of neurons that controls the fingers of your left hand, and another that controls your tongue. But what about more complex functions such as recognizing faces, using language or doing math? Are there special brain regions for those activities, or do they use general-purpose areas that serve whatever task is at hand?

Language, a cognitive skill that is both unique to humans and universal to all human cultures, "seems like one of the first places one would look" for this kind of specificity, says Evelina Fedorenko, a research scientist in MIT's Department of Brain and Cognitive Sciences and first author of the new study. But data from neuroimaging -- especially functional magnetic resonance imaging (fMRI), which measures brain activity associated with cognitive tasks -- has been frustratingly inconclusive. Though studies have largely converged on several areas important for language, it's been hard to say whether those areas are exclusive to language. Many experiments have found that non-language tasks seemingly activate the same areas: Arithmetic, working memory and music are some of the most common culprits.

But according to Fedorenko and her co-authors -- Nancy Kanwisher, the Walter A. Rosenblith Professor of Cognitive Neuroscience, and undergraduate student Michael Behr -- this apparent overlap may simply be due to flaws in methodology, i.e., how fMRI data is traditionally gathered and analyzed. In their new study, published in this week's Proceedings of the National Academy of Sciences, they used an innovative technique they've been developing over the past few years; the new method yielded evidence that there are, in fact, bits of the brain that do language and nothing else.

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