A linguistic game of 'Where's Waldo?'
This methodology is exactly what allows Fedorenko, Behr and Kanwisher to see if there are areas truly specific to language. After having their subjects perform the initial language task, which they call a "functional localizer," they had each one do a subset of seven other experiments: one on exact arithmetic, two on working memory, three on cognitive control and one on music, since these are the functions "most commonly argued to share neural machinery with language," Fedorenko says.
Out of the nine regions they analyzed four in the left frontal lobe, including the region known as Broca's area, and five further back in the left hemisphere eight uniquely supported language, showing no significant activation for any of the seven other tasks. These findings indicate a "striking degree of functional specificity for language," as the researchers report in their paper.
Future studies will test the newly identified language areas with even more non-language tasks to see if their functional specificity holds up; the researchers also plan to delve deeper into these areas to discover which particular linguistic jobs each is responsible for.
Fedorenko says the results don't imply that every cognitive function has its own dedicated piece of cortex; after all, we're able to learn new skills, so there must be some parts of the brain that are both high-level and functionally flexible. Still, she says, the results give hope to researchers looking to draw some distinctions within in the human cortex: "Brain regions that do related things may be nearby [but] it's not just all one big mush
|Contact: Caroline McCall|
Massachusetts Institute of Technology