Greater Pattern Similarity between Mother Tongue and Second Language in the Right ATL Facilitates Understanding of Written Language.

Previous research has mapped out the brain regions that respond to semantic stimuli presented visually and auditorily, but there is debate about whether semantic representation is modality-specific (only written or only spoken) or modality-invariant (both written and spoken). The mechanism of semantic representation underlying native (L1) and second language (L2) comprehension in different modalities as well as how this mechanism is influenced by L2 proficiency, remains unclear. We used functional magnetic resonance imaging (fMRI) data from the OpenNEURO database to calculate neural pattern similarity across native and second languages (Spanish and English) for different input modalities (written and spoken) and learning sessions (before and after training). The correlations between behavioral performance and cross-language pattern similarity for L1 and L2 were also calculated. Spanish-English bilingual adolescents (N = 24; ages 16-17; 19 girls) participated in a 3-month English immersion after-school program. As L2 proficiency increased, greater cross-language pattern similarity between L1 and L2 spoken words was observed in the left pars triangularis. Cross-language pattern similarity between L1 and L2 written words was observed in the right anterior temporal lobe. Brain-behavior correlations indicated that increased cross-language pattern similarity between L1 and L2 written words in the right anterior temporal lobe was associated with L2 written word comprehension. This study identified an effective neurofunctional predictor related to L2 written word comprehension.