The timing of language learning shapes brain structure associated with articulation

• Published in: Brain Structure and Function Vol. 221; no. 7; pp. 3591 - 3600
• Main Authors: Berken, Jonathan A., Gracco, Vincent L., Chen, Jen-Kai, Klein, Denise
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.09.2016; Springer Nature B.V
• Subjects: Adult; Bilingualism; Biomedical and Life Sciences; Biomedicine; Brain; Brain - anatomy & histology; Cell Biology; Female; Functional Laterality; Gray Matter - anatomy & histology; Humans; Language acquisition; Learning; Magnetic Resonance Imaging; Male; Multilingualism; Neurology; Neurosciences; NMR; Nuclear magnetic resonance; Original Article; Young Adult; Age of acquisition; Magnetic resonance imaging; Motor cortex; Accent; Voxel-based morphometry; Plasticity; Bilingualism; Gray matter density; Putamen; Brain structure; Skill learning
• ISSN: 1863-2653; 1863-2661; 0340-2061
• DOI: 10.1007/s00429-015-1121-9

We compared the brain structure of highly proficient simultaneous (two languages from birth) and sequential (second language after age 5) bilinguals, who differed only in their degree of native-like accent, to determine how the brain develops when a skill is acquired from birth versus later in life. For the simultaneous bilinguals, gray matter density was increased in the left putamen, as well as in the left posterior insula, right dorsolateral prefrontal cortex, and left and right occipital cortex. For the sequential bilinguals, gray matter density was increased in the bilateral premotor cortex. Sequential bilinguals with better accents also showed greater gray matter density in the left putamen, and in several additional brain regions important for sensorimotor integration and speech–motor control. Our findings suggest that second language learning results in enhanced brain structure of specific brain areas, which depends on whether two languages are learned simultaneously or sequentially, and on the extent to which native-like proficiency is acquired.