According to a recent study published in NeuroImage, the wiring patterns in the brain appear to reflect the grammatical characteristics unique to various languages, leaving a biological imprint that lasts a lifetime.
The study, which analyzed almost 100 brain scans of monolingual adults, found that German and Arabic speakers exhibited varying strengths of connections in specific regions of the brain's language circuit. These structural differences are believed to be the result of the cognitive demands imposed by each language, indicating that our native language can physically shape the brain.
the words of neuroscientist Alfred Anwander, "Distinct traces of each language's specific difficulties are imprinted in the brain, making us differently depending on which language we learn."
Each human language employs a distinct set of techniques to convey meaning. For example, some languages utilize intricate arrangements of prefixes and suffixes to construct complex, lengthy words, while others modify the pronunciation or arrangement of words within phrases to convey ideas.
The brain regions responsible for processing these linguistic techniques are interconnected via white matter, which facilitates efficient communication between different parts of the brain through long, cable-like nerve cells. This process of wiring different brain regions together is integral to the learning process: as we repeatedly utilize these connections, they become more established and resilient.
Although the various components of the brain's language circuit are specialized for different functions, the overall architecture of this circuitry is consistent across individuals. However, each language presents its own unique challenges, which can lead to distinct white matter networks, as explained by Anwander.
To investigate this phenomenon, Anwander and his team conducted structural MRI brain scans on 94 healthy volunteers who spoke either German or Levantine Arabic, two unrelated languages. Notably, the Arabic speakers were recent refugees to Germany and had yet to learn the German language. The scans revealed that the Arabic speakers tended to exhibit stronger connections between the left and right hemispheres, while the German speakers had a more concentrated network of connections within the left hemisphere.
“This corresponds to the specific difficulties in the respective languages,” Anwander says.
Through the comparison of MRI scans from nearly 100 individuals, researchers discovered distinct differences in brain connectivity between German and Arabic native speakers. As depicted in the accompanying image, German speakers displayed stronger white matter networks (red lines) within the left hemisphere, while Arabic speakers had denser networks (cyan lines) that spanned across both hemispheres. Each sphere in the image corresponds to a unique component of the language circuit, with its size indicating its degree of centrality. The lines illustrate the connections between nodes in the language circuit that were more robust in one group of native speakers relative to the other.
Variations in the connectivity of the language circuitry between native German and Arabic speakers
|X. WEI ET AL/NEUROIMAGE 2023|
Arabic's intricate root system, consisting of consonant trios that pair with vowel patterns to create words, may require increased activation in regions of the brain responsible for processing auditory and linguistic information. An illustrative example of this phenomenon is the root k-t-b, which generates various writing-related words such as Kitab (book), taktub (you or she writes), and maktab (office). Additionally, Arabic is written in a right-to-left direction, which the researchers suggest could necessitate greater communication between the two hemispheres of the brain.
German's syntax is both intricate and adaptable, enabling the language to convey nuanced nuances of meaning by rearranging words within a phrase. Unlike English, where altering the word order in the sentence "the woman gave the dog a ball" would compromise the fundamental message, German permits such reordering. As a result, the denser white matter connections within the left hemisphere of German speakers' brains, specifically those involved in word order analysis, could be attributed to this linguistic feature.
According to Zhenghan Qi, a cognitive neuroscientist at Northeastern University in Boston who did not participate in the research, it is conceivable that the white matter networks of Arabic speakers may have been influenced by their recent migration to Germany.
Qi suggests that even as little as one month of acquiring a new language can stimulate the right hemisphere of the brain and foster increased interhemispheric connectivity. To distinguish the impacts of language acquisition from those of the native language, Qi proposes that examining MRI scans of Arabic speakers in their home countries or monitoring changes in brain function as individuals learn new languages could be helpful.
According to Qi, the language circuit studied in the new research is involved in more than just language processing. Additionally, language learning could potentially lead to changes in nonlinguistic brain regions, suggesting that individuals with different language backgrounds may process nonlanguage information differently. While it remains uncertain whether white matter rewiring related to language impacts more than language processing, the study suggests that our native languages are not just a collection of words we learn but are integral to our identities.
X. Wei et al. Native language differences in the structural connectome of the human brain. NeuroImage. Vol. 270, April 15, 2023, 119955. doi: 10.1016/j.neuroimage.2023.119955.