Bilingual brain: a review of the most important findings

Bilingualism imposes additional requirements on the cognitive system. As such, it can be a driving force of neuroplastic changes in the brain of a person who speaks more than one language. The need to store and use two systems of representations corresponding to the two languages as well as to develop an efficient control system which allows to use the intendent, contextually appropriate language, may result in both functional and structural changes. Neuroimaging studies show that the neural organization of language representations in a bilingual brain depends to a large degree on the type of representation. Conceptual representations seem to share common neural underpinnings between the different languages. Lexical representations, related to the vocabulary and words, are processed by the same brain regions regardless of the language, however, they have been shown to be coded by distinct neuronal populations. Finally, neuroplastic reorganization of syntactic representations is highly dependent on factors related to individual experiences of bilingualism, such as age of acquisition and proficiency in the second language. Neuroplastic changes in the bilingual brain have also been linked to the increased demands that using two languages imposes on the cognitive control mechanisms. Both structural and functional changes in the brain of bilinguals were observed withing a wide network referred to as language control network. Summing up, neuroimaging studies have demonstrated that bilingualism is related to neuroplastic changes in both structure and functioning of the brain. However, the newest reports suggest the extent and intensity of the neuroplastic changes are most likely dependent on individual experiences of each bilingual speaker.