Brain Plasticity in Adulthood—ERP Evidence for L1‐attrition in Lexicon and Morphosyntax After Predominant L2 Use

Since the early 2000s, neurocognitive research on second language (L2) acquisition has been controversial as to how plastic the human brain is after puberty. Recent studies have extended this debate to first language loss (L1 attrition). This article gives an overview of the first event‐related brain potential (ERP) studies on L1 attrition and L2 learning and discusses their implications for our understanding of the bilingual brain. We will address the highly controversial question of whether L1 morphosyntax is subject to attrition in adult migrants. One previous ERP study on grammatical gender in German migrants failed to find such effects. However, ERP work on grammatical structures in English‐dominant Italian attriters demonstrated that they perceived a grammatical sentence in their L1 as ungrammatical if it violated the L2 grammar. These data suggest that the adult brain remains plastic for both L2 and L1.