Fluency-dependent cortical activation associated with speech production and comprehension in second language learners

Area of Science:

• Neuroscience
• Cognitive Science
• Linguistics

Background:

• Second language acquisition (SLA) research increasingly explores the neural correlates of language learning.
• Understanding how brain activity changes with second language (L2) proficiency is crucial for optimizing learning strategies.

Purpose of the Study:

• To investigate the relationship between L2 English fluency levels and brain activation patterns during language production and comprehension tasks.
• To identify specific brain regions whose activity is modulated by L2 proficiency.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to monitor brain activity in 30 adult Japanese-English L2 learners.
• Participants completed an oral sentence building task (production) and an oral story comprehension task.
• L2 English proficiency was assessed using the Versant English Test.

Main Results:

• During sentence building, increased L2 fluency was associated with decreased activation in the dorsal part of the left inferior frontal gyrus (dIFG), suggesting enhanced automaticity.
• During story comprehension, higher L2 fluency correlated with increased activation in the left posterior superior temporal gyrus (pSTG), indicating greater engagement in post-syntactic integration.

Conclusions:

• L2 fluency influences neural resource allocation differently for language production and comprehension.
• The findings highlight distinct brain mechanisms underlying syntactic processing and semantic integration in L2 learners.
• This study provides insights into the neural basis of L2 learning and proficiency development across different language modalities.