Subcortical volume and language proficiency in bilinguals and monolinguals: A structural MRI study

Area of Science:

• Neuroscience
• Linguistics
• Cognitive Science

Background:

• Heritage bilinguals represent a significant demographic in the U.S.
• Understanding the neural correlates of bilingualism is crucial for cognitive science.
• Subcortical gray matter's role in language acquisition remains under-explored.

Purpose of the Study:

• To investigate the relationship between language experience and subcortical gray matter volume in heritage bilinguals.
• To compare brain structure differences between bilinguals and monolinguals.
• To identify specific subcortical regions associated with L1 and L2 proficiency.

Main Methods:

• Combined data from eight MRI studies.
• Analyzed neuroimaging data from 215 heritage Spanish-English bilinguals and 145 English monolinguals.
• Correlated language proficiency (L1 Spanish, L2 English) and age of acquisition (AoA) with subcortical gray matter volume.

Main Results:

• In bilinguals, higher L1 Spanish proficiency was linked to reduced bilateral globus pallidus volume.
• Higher L2 English proficiency and earlier English AoA correlated with increased volume in the right thalamus, left accumbens, and bilateral globus pallidus.
• In monolinguals, higher English proficiency was associated with greater right pallidum volume.

Conclusions:

• Subcortical gray matter structures are significantly associated with second language learning.
• Language experience, including proficiency and age of acquisition, influences subcortical brain volumes.
• Further developmental research is needed to understand subcortical adaptation in L1 and L2 acquisition.