Earlier second language acquisition is associated with greater neural pattern dissimilarity between the first and...

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Science

Background:

• The influence of age of acquisition (AoA) and proficiency on first language (L1) and second language (L2) neural representations remains debated.
• Understanding bilingual brain networks is crucial for cognitive neuroscience and language acquisition research.

Purpose of the Study:

• To investigate how AoA and proficiency level affect neural similarities and differences between L1 and L2 brain networks.
• To quantify the degree of neural similarity between L1 and L2 during sentence comprehension in adult bilinguals.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to study 26 Chinese-English bilinguals.
• Representational similarity analysis (RSA) was used to measure neural pattern similarity between L1 and L2 processing.
• Statistical analyses controlled for the effects of proficiency level and AoA.

Main Results:

• While L1 and L2 processing engaged similar brain regions, earlier AoA correlated with greater neural pattern dissimilarity in specific frontal regions (left inferior and middle frontal gyri).
• Proficiency level did not show a significant association with neural pattern dissimilarity when AoA effects were accounted for.
• AoA demonstrated a more substantial impact on neural distinctiveness between L1 and L2 than proficiency.

Conclusions:

• Earlier acquisition of an L2 results in more distinct neural activity patterns compared to the L1.
• AoA is a stronger determinant of neural pattern dissimilarity between L1 and L2 than L2 proficiency level in adult bilinguals.