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The Science behind Multilingual Aphasia

Before delving into bilingual aphasia, here’s some background. Contrary to popular belief, being bilingual isn’t “black-and-white”; it’s a spectrum. Some bilinguals may be able to speak both languages perfectly; others may be able to understand but not speak, and more. Being bilingual and being monolingual require similar parts of the brain, and with similar physical restraints of the brain- referred to as neuroanatomical substances- it could be assumed that speaking any language requires the use of similar neural structures. However, they do engage neural structures in different manners.

In a study conducted by Professor Ping Li (from Penn State University), it was discovered that Chinese and English words overlap in different “hemispheres” of the brain. His work shows that the right hemisphere is utilized when reading Chinese words despite language generally being lateralized to the left hemisphere in individuals who are right-handed. The right hemisphere is involved because of “the visual features of Chinese characters and the lexical tones carried by Chinese words” (psychology.org). It was also proven from this study that English and Chinese have differing portrayals of nouns and verbs, but the question remained: how do bilinguals store and process these languages? Apparently, in specific circumstances, bilinguals learn the word information for both languages separately- “word class” is vital for their language development. Therefore, it was concluded that the bilingual brain is “highly plastic”- meaning moldable and able to process quite a lot. Late bilinguals have more of a neural linguistic sensitivity to a new language, as their language skills in their first language are much more developed.

Now, to address the title: multilingual aphasia. What is it? Multilingual aphasia is a case in which someone who previously spoke more than one language struggles with those languages after a traumatic brain injury (most conditions involve a stroke).  In some incidents, the person who suffered from the brain trauma never regains one language. Generally, a clear parallel is seen between the recovery of both languages, while others have fluctuating levels of fluency in each language. In a few circumstances involving bilingual victims to a trauma, there have been reports of them being perfect in one language and dysfluent in one language one day, and vice versa the next.  The rate at which each language is regained is obviously related to which one they relearn writing, reading, speaking with others, etc. So, the question is- how is this possible? In fact, several cases that researchers looked into involve the speaker of the language maintaining the same control functions for both languages, but inhibited from speaking it as a result of embarrassment or mental restraint. Still, on the bright side, there are a large number of situations in which both languages are fully recovered.

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In conclusion, multilingual aphasia is very complex- scientists still don’t have a full comprehension of the brain functions involved, especially bilingual brain functions. They continue to explore bilingual neuroscience and the intricacy of diseases such as bilingual aphasia.

Edited by: Karen Yung and Mehek Dedhia