The Neural Basis of a Bilingual Brain

By Anjanie Khimraj
MBS 2018, Geisinger Commonwealth School of Medicine
akhimraj@som.geisinger.edu 
Mentor: Dr. Brian Piper, PhD

Researchers have hypothesized that bilinguals, people who speak more than one language, have the capacity to outperform people, who only speak one language, in highly ordered brain tasks. In order to test this, the scientists used several different neuroimaging techniques to capture images, and measure the density of tissues in various parts of the brain.

Bilinguals are constantly choosing and replacing words when switching between languages. However, they have the capacity to incorporate and use different brain processes to either inhibit, shift or update words or phrases from their spoken language. These are all tasks that bilinguals use the most because they play a significant role in the processing of language, and they enable bilinguals to perform brain tasks that require higher cognitive abilities.

The specific areas with a large difference in the density and volume of brain tissues for bilinguals, when compared directly to monolinguals, were the inferior parietal cortex and lobe, the left caudate nucleus, dorsolateral and rostrolateral prefrontal cortices, superior temporal gyrus and inferior frontal gyrus (please, refer to Figure 1). Most of these areas of the brain play an important role in language, whether it relates to understanding languages and their content, or using language to organize behavioral and social skills. Additionally, the areas more affected are in the left hemisphere of the brain because this hemisphere is not only responsible for language, but also for one’s working memory and reasoning skills.

Learning a second language at a younger age helps brain development and lessens the risks of developing neurological disorders at an older age. This is possible because a person speaking more than one language is using their brain at a higher capacity than someone who speaks a single language. Therefore, the bilingual brain works at a consistently higher rate even when performing the simplest tasks such as language translation when speaking to their family or friends.

In my perspective, both the ability to be bilingual, and its capacity to cause a configuration of the neural network is phenomenal because individuals from different ages are able to do it. For instance, imagine you are traveling one day to school or work using public transportation. You then observe a preschooler speaking to her parents in her native tongue, and then to her sibling in English. Being a monolingual, I would become perplexed by this preschooler’s ability to rapidly switch been languages because we usually think that it would be more common in grade schoolers and beyond. We are all unique in our individualized ways and being bilingual is one of those.

This skill serves as a great advantage because it comes with prolonged benefits during the different stages of development, especially in adulthood and beyond. In my perspective, it allows you to use areas in your brain that you may not as a monolingual. For future applications, more studies should be conducted to investigate if the same or newer areas in the brain are activated, when someone learns a second language and how it compares between bilinguals or multilinguals.



Figure 1 The different parts of the brain that are activated during language processing in bilinguals (Wong et al, 2015).

And here is a link to a great animation on this topic.