Researchers from the Center for the Study of Learning at Georgetown University have found that people who are bilingual in two spoken languages have more gray matter in their nervous systems, according to a new study published in the journal Cerebral Cortex.
Gray matter is the component of the central nervous system that houses neuron cells, synapses, and other key components of the neural network. Gray matter is in charge of the systems that control memory, the senses, emotions, speech, decision making, and self-control.
Gray matter can differ from person to person based on their experiences and memories. For example, another study showed that taxi drivers in London had more gray matter in the areas of the brain involved in spatial navigation.
The bilingual’s cognitive advantages
Although it’s been thought for a while that bilinguals held certain cognitive advantages over their monolingual counterparts, such as greater attention and short-term memory, this is thought to be the first study that confirms bilingual brains as being physically different.
Previous studies of those advantages, collectively known as “executive function”, have been flawed.
“Inconsistencies in the reports about the bilingual advantage stem primarily from the variety of tasks that are used in attempts to elicit the advantage,” says senior author Guinevere Eden, DPhil, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC). “Given this concern, we took a different approach and instead compared gray matter volume between adult bilinguals and monolinguals. We reasoned that the experience with two languages and the increased need for cognitive control to use them appropriately would result in brain changes in Spanish-English bilinguals when compared with English-speaking monolinguals. And in fact greater gray matter for bilinguals was observed in frontal and parietal brain regions that are involved in executive control.”
Gray matter growth not due to increased vocabulary
To further narrow down the cause of these executive control advantages, the team also compared the gray matter of American Sign Language users and that of Spanish-English bilinguals. There was not the same increased gray matter in the ASL speakers.
The researchers reason that simply having a larger vocabulary in your brain, like both bilingual groups, is not enough for cognitive growth. That growth only comes from having to manage between two spoken languages in daily life. ASL speakers are using both languages at the same time when communicating.