Complex brain network properties in late L2 learners and native speakers

Whether the neural mechanisms that underlie the processing of a second language in highly proficient late bilinguals (L2 late learners) are similar or not to those that underlie the processing of the first language (L1) is still an issue under debate. In this study, a group of late learners of Spanish whose native language is English and a group of Spanish monolinguals were compared while they read sentences, some of which contained syntactic violations. A brain complex network analysis approach was used to assess the time-varying topological properties of the functional networks extracted from the electroencephalography (EEG) recording. Late L2 learners showed a lower degree of parallel information transfer and a slower propagation between regions of the brain functional networks while processing sentences containing a gender mismatch condition as compared with a standard sentence configuration. In contrast, no such differences between these conditions were detected in the Spanish monolinguals. This indicates that when a morphosyntactic language incongruence that does not exist in the native language is presented in the second language, the neural activation pattern is configured differently in highly proficient late bilinguals than in monolinguals. •The time-varying topological properties of EEG functional networks are examined and assessed.•Native and late L2 learners reading mismatching and standard sentences were compared.•Late L2 learners showed a lower graph-efficiency and longer path lengths in the mismatch condition.•No such differences were detected in the monolinguals.•Neural pattern are different in highly proficient late bilinguals than in monolinguals.