Abstract
While it has long been assumed that brain plasticity declines significantly with growing maturity, recent studies
in adult subjects show grey and white matter changes due to language learning that suggest high adaptability of brain structures
even within short time-scales. It is not known yet whether other language development phenomena, such as attrition, may also be
linked to structural changes in the brain. In behavioral and neurocognitive research on language attrition and crosslinguistic
influence, findings suggest high plasticity as language interaction patterns of bilingual speakers change constantly and from
early stages of language acquisition onwards. In this paper we will speculate on possible links between brain plasticity and L1
attrition in adult bilinguals, with particular attention to a number of factors that are put forward in memory frameworks in order
to explain forgetting: time elapsed, frequency of L1 use, and interference from L2. In order to better understand the time-scales
involved in the plastic changes during bilingual development, we then discuss some recent studies of re-exposure to L1 in formerly
attrited immigrants, and their implications with respect to brain plasticity.