Languages in the neuronal mirror: Researchers report that mother tongues with very different characteristics lead to peculiarities in the interconnection of the language regions of the brain. Through investigations using magnetic resonance tomography, they were able to show how the system adapts to the special requirements of the respective language using the example of Arabic compared to German.
The ability to convey complex information to our fellow human beings through language is one of our species' most important recipes for success. The brain functions on which this system is based are therefore also the focus of brain research. Some fundamental aspects of language processing are already known. Studies have identified certain areas and networks in the brain that are responsible for processing the meaning of certain sound patterns and for interpreting the grammatical structure of sentences.
However, the different languages of humanity in some cases differ greatly in the way in which this so-called semantic and syntactic information is encoded. This represents one of the great challenges of learning a new language whose development history differs significantly from one's own mother tongue. Against this background, a team from the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig has now investigated the extent to which the different features of languages are reflected in structural features in the brain.
Targeting German and Arabic
They examined this using the example of the languages German and Arabic, which differ significantly in the formation of sound meanings as well as in sentence structure and grammar. 47 German and 47 Arabic native speakers took part in the study, each of whom had no knowledge of the other language. Their brains were scanned in a magnetic resonance imaging (MRI) scanner as part of the study. The researchers explain that a technique called "diffusion-weighted imaging" was able to provide information in the recordings about how intensively certain brain areas are wired together via neuronal connections.
As it turned out, characteristic differences between the two groups can actually be determined: "Arabic native speakers showed a stronger connection between the left and right hemispheres of the brain than German native speakers," says senior author Alfred Anwander. "This reinforcement was also found between semantic language regions and could be related to the relatively complex semantic and phonological processing in Arabic," explains the scientist. In the German native speakers, on the other hand, the researchers found a more intensive connectivity in the language network of the left brain hemisphere. They suspect that this peculiarity could be related to the comparatively complex syntactic processing in the German language. As they explain, this linguistic aspect is due to the rather free word order and the greater distance between the dependent sentence elements.
Neural traces of the language requirement
The researchers conclude that the results are now among the first to document clear neuronal differences between people who grew up with different mother tongues. “Brain connectivity is influenced by learning and the environment during childhood, which affects cognitive processing, i.e. thinking, in the adult brain. Our study provides new insights into how the brain adapts to cognitive demands - so our structural network of language is shaped by the mother tongue," says Anwander.
His team now wants to stay on the ball and continue researching the linguistic processing differences in the brain. In a next study, the researchers plan to investigate the extent to which structural changes in the brain can be detected when people learn a new language with characteristics that are foreign to them. Specifically, they want to analyze this with Arabic-speaking adults while they are learning German for six months.
Source: Max Planck Institute for Human Cognitive and Brain Sciences, specialist article: NeuroImage doi: 10.1016/j.neuroimage.2023.119955