Poster E64, Saturday, August 18, 3:00 – 4:45 pm, Room 2000AB

Associations Between Degree of Bilingualism, Executive Function, and Brain Maturation in English-Spanish Bilingual Children

Marybel Gonzalez1, Tamar Gollan2, Anders Dale2, Terry Jernigan2;1Children's Hospital Los Angeles, 2University of California, San Diego

Children who are raised bilingual can vary individually across language skills and experience, including vocabulary skill, the extent they practice and hear one language relative to another (i.e., language balance), and language mixing practices. The associations between language characteristics, executive function, and brain maturation were examined in 48 English-Spanish bilingual children ages 5 – 13 years of age. Bilingual children were compared to an age-matched English monolingual group of 53 children. Children were recruited across San Diego County, California. Executive function measures included response inhibition, inhibitory control, and cognitive flexibility. Expressive vocabularies in both languages were obtained in bilinguals using the Multilingual Naming Test (MINT). Parental report assessed the degree of language experience in one language relative to another, based on questions of language use in the home and school environment. Language mixing practice was also assessed via parental report of whether the child mixed words or sentences from both languages in speech. Diffusion-weighted images (DWI) were obtained for both groups. Bilingual children underperformed on executive function tasks compared to the monolingual children. Socio-economic status (SES) mediated group differences in cognitive flexibility, however not for inhibitory control performance.  Within the bilingual group, more balance in language experience predicted better response inhibition performance, while lower frequencies of language mixing predicted better inhibitory control. Further, a measure of white matter maturation, fractional anisotropy (FA), was compared in bilingual children to monolingual children in white matter fiber tracts chosen a priori. Monolingual children showed higher FA (more mature values), in the superior longitudinal fasciculus (SLF) compared to the bilingual group, independent of SES.  While there were no group differences in the whole segment of the inferior fronto-occipital fasciculus (IFOF), post-hoc analysis revealed monolinguals had higher FA in the anterior and middle IFOF, while bilinguals had higher FA in the posterior IFOF.  Within the bilingual group, higher FA in the anterior cingulum was predicted by more balanced vocabularies in the two languages, independent of age and sex. There was an interaction effect of language experience balance by the rate of language mixing on FA in the anterior cingulum. Specifically, the association between higher FA in the anterior cingulum and more balance in language experience was evident in bilinguals with reported low rates of language mixing, while the association was weaker in bilinguals with reported high rates of language mixing. A similar interaction effect on FA in the anterior cingulum trended for vocabulary balance by the rate of language mixing. Findings from this study support a relationship between individual differences in degree of bilingualism, executive function, and brain maturation.

Topic Area: Multilingualism