Detailing how your brain handles your internal dictionary

While words can obviously occupy space on a page, or even bulk up the size of an email, it feels a bit stranger to think that words also occupy space in your brain. Scientists have been investigating this idea for a while, looking brain cell activity when the brain’s owner (user? brain itself?) is interpreting a specific word. Using words seems to be funneled through shared neural anatomy, such as visual centers when you read text, but individual concepts seem to correspond with specific pieces of your cerebral cortex, the outer layer of lumps and folds on a human brain.

Estimated activity

For a long time, scientists have only had some scattered landmarks for these lexical landmarks. Early on, abstract concepts were thought to be divided up into large regions, such as a slab of brain cells corresponding with anything related to emotion. Other studies managed to map words or sentences to general regions of the brain, but locations were still rough estimates. Now, thanks to seven volunteers who spent hours listening to the Moth Radio Hour in an fMRI, researchers from the University of California, Berkeley have plotted out 60,000 to 80,000 pea-sized regions for different words. Aside from the enjoyment of the volunteers, listening to narratives also ensured that a wide variety of language was used in a very “real” way, closely corresponding to what our brains handle every day.

Refining conceptual regions, with storytime

Once the neural activity was recorded, researchers started breaking it down, and comparing it to the what words had been heard. They broke the stories into 985 concepts that corresponded with locations on the brain. When mapping these words and concepts across a cerebral cortex, it became clear that words were distributed all over, but was clustered by concept, which actually lines up as a refinement of earlier studies. So for example, “family,” “home” and “mother” were located near each other (above and behind the right ear.) The brain handled homophones well too, properly placing “top” with both clothing and numbers and measurements.

The next step is to expand the number of volunteers, and ensure that a wider variety of people’s vocabularies are mapped. This is a good idea for any study, but in this case the authors are especially interested in the fact that of the seven brains studied, there is very little variation in where words are kept. If that holds true across a wider variety of people, it may provide clues about underlying, inherent frameworks to how our brains handle language on a basic level.

Source: Words’ meanings mapped in the brain by Meghan Rosen, Science News