Bilingualism: A Tale of Brain-changing Experiences (Lecture)

The capacity of the brain to rewire when dealing with demanding experiences has far-reaching implications for effective learning or facing ageing in our societies. Bilingualism is known to change our brain structure, but the nature of such adaptations remains poorly understood, and the field produces results that are often inconsistent. This talk will shed new light on bilingualism-related brain changes by viewing them through the prism of general principles of experience-dependent neuroplasticity. According to these principles, demanding experiences impact brain architecture in non-linear ways and are governed by the quantity and quality of experiences that induce them.

In two studies, we investigated the potential non-linear effects of various quantified bilingual experiences on grey matter volumes. We focused on regions known to be affected by bilingual practices. The first study examined brain adaptations linked to composite scores of general bilingual experiences. The results reveal that engagement in bilingual language use can trigger region-specific grey matter increases, either sustained or followed by volumetric decreases, depending on the quantity of bilingual experiences. The second study examined brain adaptations induced by habitual code-switching practices, which impose different cognitive demands. The results suggest qualitatively diverse volumetric trajectories for the different code-switching types. These findings highlight that various bilingual experiences may impact the brain in dynamic, yet systematic ways. I will argue that a successful understanding of bilingualism-induced brain changes requires incorporating neurobiological principles of experience-dependent neuroplasticity. Moreover, it is necessary to consider the complexity of bilingual experiences carefully. Such an approach can offer explanations of bilingualism-induced brain effects that are not necessarily simple but rather adequate.