Multilingual processing in the brain

Abstract

In this paper, in contrast to previous neuroimaging literature reviews on first language (L1) and second language (L2), the focus was only on neuroimaging studies that were directly conducted on multilingual participants. In total, 14 neuroimaging studies were included in our study such as 10 functional magnetic resonance imaging, 1 positron emission tomography, 2 magneto encephalography and 1 electroencephalography. Surprisingly, not many neuroimaging studies have been conducted on multilingual participants to date. As a result, most conclusions that are drawn about multilingual processing are in fact solely based on bilingual processing. Moreover, the few multilingual studies that were conducted frequently showed serious methodological flaws, often due to the practical limitations in terms of accessing a large homogeneous multilingual group. In future research, more multilingual neuroimaging studies are needed, in which factors such as language proficiency, age and manner of acquisition, language exposure and linguistic distance between the spoken languages, are better controlled for. Currently, these factors can explain away a large part of the differences that are found in brain activation between L1, L2 and L3. Finally, there is a need for more sophisticated neuroimaging techniques in order to capture non-invasive activity.