New research mapping the brain’s “semantic system” – regions that work together to derive meaning from words we hear every day – shows that language is processed across the entire brain, rather than just in the left hemisphere, as previously thought.
What is more, the processing regions are remarkably similar in each individual.
For the study, led by Jack Gallant at the University of California, Berkeley, seven participants listened to narrative stories for two hours, while their brain activity was monitored by MRI.
“Most earlier studies of language in the brain have used isolated words or sentences,” the researchers explain. “We used natural, narrative story stimuli because we wanted to map the full range of semantic concepts.”
The stories contained different concepts including descriptions of people, food and tools, and the researchers recorded which regions of the brain were activated on hearing about these different topics.
They found that people appear to process language about certain topics in similar brain regions.
“Our study found that different individuals have remarkably similar semantic maps,” the research says.
For example, most of us comprehend words about people in a particular part of our brain, which is surrounded by other parts that process visual words, number words, and words about touch. More than 100 different parts of the brain, across both the left and right hemispheres, were part of this semantic system.
The team has developed a sort of atlas, outlining which parts of the brain process meaning across different language topics.
“The resulting maps show that semantic information is represented in rich patterns that are distributed across several broad regions of cortex,” say the researchers.
“Furthermore, each of these regions contains many distinct areas that are selective for particular types of semantic information, such as people, numbers, visual properties, or places.”
The researchers acknowledge that the similar life experience across all the participants may have contributed to the results, and further studies are needed to expand upon the findings.
The study was described in the journal Nature.