Poster B51, Thursday, August 16, 3:05 – 4:50 pm, Room 2000AB
Neural plasticity of speech and reading networks associated with language learning
Kshipra Gurunandan1, Manuel Carreiras1,2, Pedro M. Paz-Alonso1;1BCBL - Basque Center on Cognition, Brain and Language, San Sebastián, Spain, 2Ikerbasque - Basque Foundation for Science, Bilbao, Spain
Learning a new language offers an excellent window to study neural plasticity. Functional and structural changes have been documented across the lifespan in studies of language-learning and literacy acquisition. Monolingual adults typically exhibit well-integrated speech and reading networks, an effect that is thought to be universal across highly contrastive languages (Rueckl et al., 2015). While language networks in monolinguals tend to be left-lateralized (Pujol et al., 1999), bilinguals exhibit less consistent lateralization patterns in their language networks due to variability in the age of acquisition, exposure and proficiency in their second language (L2). Little is known, however, about the neural changes associated with the process of learning a new language in adulthood. More specifically, it is still unknown whether bilinguals exhibit the convergence between speech and print networks characteristic of monolinguals, or whether cortical representations within and between languages change as a function of L2 proficiency. The present study was aimed at investigating functional changes associated with learning a new language during adulthood. We examined: 1) the convergence of speech and reading networks in L1 and L2, 2) the laterality of the language networks at different stages of learning a new language (intermediate and advanced), and 3) the effect of acquiring an L2 in the coupling of the primary auditory cortex and primary visual cortex with the speech and reading networks. Thirty-four adult (mean age = 46.5 years; 17 male) native speakers of Spanish, either at the intermediate or advanced levels of learning Basque, underwent functional MRI scanning while performing an animacy judgment task with spoken and print stimuli in their L1 and L2. Behavioral results showed a group by language interaction, with equal accuracy in the L1 and differential accuracy in the L2 between the intermediate and advanced language-learning groups. fMRI results revealed 1) a high level of convergence between speech and reading networks in both L1 and L2; 2) greater right-lateralization of the L2 in advanced relative to intermediate learners; and 3) between-group differences in the laterality of whole-brain functional connectivity with sensory areas for speech and reading, suggesting an effect of L2 learning on these networks. In sum, our study revealed considerable plasticity of the language networks in the adult brain, with increasing right lateralization of the L2 networks corresponding with concomitant proficiency increases.
Topic Area: Multilingualism