Our Brains Have a Map for Numbers

It is as if there is a number line in our heads

By Emilie Reas

“Come on. Get out of the express checkout lane! That’s way more than twelve items, lady.”

Without having to count, you can make a good guess at how many purchases the shopper in front of you is making. She may think she’s pulling a fast one, but thanks to the brain’s refined sense for quantity, she’s not fooling anyone. This ability to perceive numerosity – or number of items – does more than help prevent express lane fraud; it also builds the foundation for our arithmetic skills, the economic system and our concept of value.

Until recently, it’s remained a puzzle how the brain allows us to so quickly and accurately judge quantity. Neuroscientists believe that neural representations of most high-level cognitive concepts – for example, those involved in memory, language or decision-making – are distributed, in a relatively disorganized manner, throughout the brain. In contrast, highly organized, specialized brain regions have been identified that represent most lower-level sensory information, such as sights, sounds, or physical touch. Such areas resemble maps, in that sensory information is arranged in a logical, systematic spatial layout. Notably, this type of neural topography has only previously been observed for the basic senses, but never for a high-level cognitive function.

Researchers from the Netherlands may have discovered an exception to this rule, as reported in their recently published Science paper: a small brain area which represents numerosity along a continuous “map.” Just as we organize numbers along a mental “number line,” with one at the left, increasing in magnitude to the right, so is quantity mapped onto space in the brain. One side of this brain region responds to small numbers, the adjacent region to larger numbers, and so on, with numeric representations increasing to the far end.

Read more:

http://www.scientificamerican.com/articl...map-for-numbers