Shared and distinct neural correlates of first and second language morphological processing in bilingual brain

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Science

Background:

• Morphology is vital to language, but its neural underpinnings in bilinguals are unclear.
• Understanding how first language (L1) and second language (L2) morphology are processed is key to bilingualism research.

Purpose of the Study:

• To investigate similarities and differences in neural processing of L1 and L2 morphology in Chinese-English bilinguals.
• To explore the brain mechanisms underlying morphological processing in bilinguals.

Main Methods:

• Adult Chinese-English bilinguals completed a morphological priming lexical decision task.
• Electrophysiological and optical brain responses were recorded concurrently using electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS).

Main Results:

• Functional near-infrared spectroscopy (fNIRS) showed distinct neural patterns for morphological versus semantic priming in the left fronto-temporal network.
• L1 Chinese processing activated the left prefrontal cortex more than L2 English during morphological parsing.
• Early Left Anterior Negativity (ELAN) indicated cross-language morphological processing differs in degree, not kind.
• Shared early (P250) and late (300–500 ms negativity) structural parsing processes were observed for both L1 and L2.

Conclusions:

• Results support a unified competition model of bilingual development.
• Bilinguals appear to utilize L1 neural resources for L2 morphological representation and processing.