In 2013, a group of researchers from the University of Edinburgh published the largest study to date about the correlation between bilingualism and progression of dementia and other cognitive diseases like Alzheimer’s. The subjects were 648 patients from Hyderabad, the capital city of the state of Telangana, in India. Telugu and Urdu are the predominant languages in that region, where English is also commonly used. Most of the residents of Hyderabad are bilingual, 391 of whom were part of the study. The conclusion was that the bilingual patients had developed dementia, on average, four and a half years later than the monolingual ones, strongly suggesting that bilingualism has a deep impact on neurological structures and processes.
The process of acquiring a second language might be one we dedicate a lot of time and effort to, at school for example, but in some cases it happens naturally (picking up French after moving to Paris, for instance). So how can it be that this process, regardless of how it takes place, has such a big impact on the brain?
To the left cortex and beyond
It has long been established that humans’ capacity to use their native language is stored in the left hemisphere of the brain in over 90% of the normal population. The main parts of the brain involved in language processes are the Broca’s area, located in the left frontal lobe, which is responsible for speech production and articulation, and the Wernicke’s area, in the left temporal lobe, associated with language development and comprehension.
Language learning, however, is a complex procedure that scientists have determined is not limited to any hemisphere of the brain, but instead involves information exchange between the left and the right sides. Nothing that comes as a surprise, if we consider just how many elements a single language entails.
The professor of Psychology and Linguistics at Pennsylvania State University Dr. Ping Li explains that full knowledge of a language includes remembering the words (lexicon), learning its sound system (phonology), acquiring the writing system (orthography), getting familiar with the grammar (syntax) and picking up the subtle ways to express oneself (pragmatics). These distinct linguistic elements require the brain to activate different parts, including the frontal and parietal cortical regions, the frontal and temporal regions, the occipital and temporal-parietal regions and the frontal and subcortical regions. Also involved in the process is the corpus callosum, a white matter pathway that connects the left and the right hemispheres, enabling the transfer and integration of information between them.
But the complexity doesn’t stop here. The part of the brain where humans store a second language varies according to the age they acquire it. A study conducted at the Memorial Sloan-Kettering Cancer Center in New York with the help of 12 bilingual volunteers revealed that children who learn a second language early on store it together with their native language, while in adult learners it is saved in a different area of the brain. This suggests that the brain accommodates languages separately at different points of the subject’s lifespan, which means the structures involved in language acquisition and processing are not fixed, but change, undergoing cortical adaptation when a new language is added.
Change that’s good for the brain
The process of learning something has an effect on the brain similar to the one exercizing has on the muscles. If we make them move, they increase in size and become stronger. The same thing happens to the brain. By putting it to work, we’re making it alter its structure, while at the same time improving certain functions. Because language learning is such a complex process, the brain regions involved in it are enhanced. This is reflected in an increase of white and gray matter (that contains most of the brain’s neurons and synapses) in said regions.
When it comes to the corpus callosum, for instance, several studies suggest that the data transfer between the left and the right hemispheres that happens during the acquisition of a second language contributes to an increase in its white matter volume and in the number of fibers that provide greater cortical connectivity.
For people who speak more than one language, it takes imperceptible effort to switch between them. This mental exercise appears to be what boosts gray matter volume in other regions of the brain. Further research conducted by Dr. Ping Li shows that the anterior cingulate cortex increases in size because of the important role it plays in monitoring which language is being spoken and keeping the other language(s) from intruding our speech.
Research on this topic has also been conducted at the Center for the Study of Learning at Georgetown University Medical Center. Lead by senior author Guinevere Eden, a team compared gray matter volume between adult bilinguals and monolinguals and was able to observe greater gray matter in the bilingual individuals’ brains, specifically in frontal and parietal brain regions that are involved in executive control. Changes have further been observed in the dorsolateral prefrontal cortex of bilingual individuals. This is the region of the brain that plays a role in “executive function, problem solving, switching between tasks and focusing while filtering out irrelevant information,” as explained by Mia Nacamulli in a Ted-Ed talk about the benefits of bilingualism.
The brain is plastic, it’s fantastic
For a very long time, scientists didn’t believe it was possible for the brain to change throughout life. The overall assumption was that the brain would develop up until a certain point, from which its connections would become fixed and then eventually start to fade. It was also believed that there was no way to repair the brain after it suffered injury. However, recent studies proved the exact opposite: that the brain, in fact, never stops changing as a response to different experiences.
This is explained by the concept of neuroplasticity. In neuroscience, “plastic” refers to the capacity that materials have to change and be moulded into different shapes. It is the brain’s ability to adjust its physical structure and, this way, repair damaged regions, grow new neurons, rezone regions to perform new tasks and build networks of neurons that allow us to remember, feel and dream things. It is, furthermore, what allows us to explain how the brain is able to mould itself following second language acquisition.
Neuroplasticity generally decreases as we grow older, which is why it’s easier for children to become fluent in a second language than adults. The infant brain is more plastic, making it more easily adaptable and able to deal with the challenges of speaking two languages, like having to switch between one and the other in different contexts. This doesn’t mean that adults should give up learning a new language all together, on the contrary. The benefits associated with brain changes due to learning have been observed in sequential bilinguals (people who learn their second language later on in life) as well.
The changes to the brain aren’t felt like other changes in the body, such as growing pains, but translate into cognitive advantages. Learning a second language is, as mentioned before, a complex process that involves different brain regions and puts them to work. On top of that, once other languages are mastered, switching back and forth between them is more demanding on the brain. This mental gymnastics of sorts provides the brain with better compensatory mechanisms. The executive control center of the brain is what manages this dual or multiple language system, so as we learn how to use the right language at the right time, we are exercising the regions of the brain responsible for our executive function through neuroplasticity.
A stronger executive function means bilingual or multilingual individuals are generally better at analysing their surroundings, multitasking, and problem solving. There’s also evidence of them having a larger working memory even if the task at hand is not related to language. The biggest benefit, however, is the increased ability to cope with degenerative diseases like dementia or Alzheimer’s, as demonstrated in several studies like the one mentioned in the beginning. This doesn’t mean that the brains of bilinguals are not susceptible to cognitive degeneration, but they are better able to cope with the damage, thanks to the compensatory mechanisms arising from knowing, and using, a second language.
The concept of neuroplasticity, along with its link to language learning, helps clear up the evolution of the human brain throughout life, but most of all it shows that, up to a certain extent, we are able to control that transformation. The problem is, most of the times, we choose not to. Alvaro Pascual-Leone, a neurologist at Harvard Medical School, puts it best:
"We’re lazy, we don’t get out of our comfort zones, we stop learning new things. The fact is that whatever you do, from activities to relationships to thoughts, ultimately enters the brain and affects it. But we can harness that property of the brain for our own benefit."
Given the research, there’s no denying that learning, whatever subject we choose, has profound positive effects on us, that go far beyond making our CVs look better during a job interview. I don’t know about you, but I’m already dusting off my Duolingo app.
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