For many of us, anxiety about math performance isn't so much a question of whether it will happen, but at what level of math it kicks in (in my case, Calculus III, sophomore year in college). But, as the authors of a new paper on math anxiety point out, most forms of higher math didn't even exist until a few centuries ago. It's very unlikely that this sort of anxiety has evolved a specialized brain structure dedicated to it. So, the researchers used a combination of math quizzes and functional MRI scans to identify the areas of the brain associated with the fear of math.

It turned out to be one that was previously associated with the experience of physical pain. And it doesn't appear to be the first time that area has been borrowed for other purposes by evolution: it also helps register the discomfort of social rejection.

The test the authors devised was pretty ingenious. First, they took their subjects (28 total) and divided them based on their level of distaste for math, using a series of questions termed the Short Math Anxiety Rating-Scale, or SMARS. Then, they put them in the MRI tubes and exposed them to a series of quizzes, some math focused, others targeting verbal skills. To trigger anxiety, a small warning indicator changed color based on the nature of the next test: a yellow circle indicated math was on its way, while a blue square indicated verbal questions would follow.

This gave them several ways to eliminate extraneous signals. For one, they could detect the difference between people experiencing discomfort while performing math and when those same people were simply dreading the need to do so. And they could also separate it from a general performance anxiety, since this should also be present for the verbal tests. Finally, they could zero in on those subjects whose SMARS scores indicated they had anxiety about math performance.

This left them focusing on a limited number of brain regions, with the signals being strongest in the bilateral dorso-posterior insula, an area deep in the core of the brain. This was one of the key regions that was active ahead of any actual attempts to perform math, and didn't seem to be triggered by test-taking in general. Or, as the authors put it, "the neural responses in the current study aren’t merely an artifact of anticipating having to do a harder task; rather, this response appears to be specific to anticipating doing a math task."

In fact, getting signaled that a word test was coming actually dropped activity in the insula by a significant margin. The authors speculate this could reflect a "visceral relief" about being spared the need to do further math. "Anticipating the word task may have served as a kind of refuge," they suggest, "in that, for the moment at least, it meant one didn’t have to do math.

This region of the insula has been associated with the experience of pain in a variety of studies. So, the authors consider a number of other ideas about the activities that normally go on in this chunk of the brain. Some have suggested that it's actually involved in the recognition of events that threaten to cause bodily harm and the pain associated with it, while others have indicated it can be triggered by indirect forms of pain, such as social rejection. But the authors note the majority of published studies associate it with pain, and that it's possible to induce the experience of pain simply by stimulating the insula.

So, their conclusion is that we are actually dealing with a pain response, and one that's not triggered by doing math. "It is not that math itself hurts; rather, the anticipation of math is painful," they suggest. However, that pain may be enough to keep people from engaging with math during their school years. The authors point out the study also gave them a chance to confirm that the anxiety correlated with poor performance on the test questions.

PLoS one, 2012. DOI: 10.1371/journal.pone.0048076 (About DOIs).