García-pentón, L. 1 , Duñabeitia, J. A. 1 , Pérez, A. 1 , Fernández, Y. 1 & Carreiras, M. 1, 2
1 BCBL
2 IKERBASQUE
Our previous study suggested higher-connected and more efficient sub-networks developed by young-bilinguals. These sub-networks comprised mostly regions devoted to language processing and monitoring. However, which aspects of bilingualism contribute to these differences and the exact nature of these sub-networks is unclear. Additionally, how the organization of the brain networks develops over time during bilinguals' lifespan need to be assessed. The aim of the current study was to investigate whether the structural brain network changes over time comparing young and old adults bilinguals and monolinguals. Also to investigate how the age-of-acquisition and proficiency of second-language modify the brain network. To determine between-groups different connectivity patterns we employed DW-MRI tractography techniques and a network-based statistic. Any difference was found between elderly bilinguals and monolinguals. Instead, we found a positive correlation in young bilinguals between age-of-acquisition and interconnectivity in a set of regions (i.e. L_insula, L_precuneos, R_inferior-occipital-gyrus, R_middle-temporal-pole). We also found a negative correlation in old bilinguals between proficiency and interconnectivity in another set of regions (i.e. L_Heschl, R_medial-superior-frontal, R/L_medial-orbitofrontal, R_inferior-orbitofrontal cortex). The bilingual-specific neural sub-networks found in our previous study were not reproduced in these old adults. These could suggest a high-level dynamism and plasticity across lifespan of the neural networks supporting languages. Also, these findings could suggest that these dynamic circuits may be modulated by the age-of-acquisition and proficiency of second-language.