This review article provides an overview of the neural correlates of second language (L2) morphosyntactic processing of the past 20 years. Morphosyntactic processing is of great relevance for our understanding of second language acquisition as it is believed to be more sensitive to age of acquisition (AoA) and maturational constraints than other linguistic sub-processes, i.e., lexical- and semantic processing.
In this review we present the more general questions raised by the first neuroimaging studies, namely, whether L1 and L2 neural representation of morphosyntax is shared or segregated. Next, we present studies that addressed the impact of AoA, proficiency level, and language transfer on L2 morphosyntactic processing and representation and their findings. We then discuss these findings in light of the procedural/declarative and unified competition models. Finally, we suggest some future directions for studies investigating L2 morphosyntactic processing using neuroimaging techniques. With this article we aim to provide the reader with an overview of what is currently known in terms of L2 morphosyntactic representation and processing and emphasize aspects that have remained understudied.