Comparison of Activation in the Prefrontal Cortex of Native Speakers of Mandarin by Ability of Japanese as a Second Language Using a Novel Speaking Task.

Li Cong,Chinami Ishizuki,Hideki Miyaguchi

doi:10.3390/healthcare9040412

Abstract

Evidence shows that second language (L2) learning affects cognitive function. Here in this work, we compared brain activation in native speakers of Mandarin (L1) who speak Japanese (L2) between and within two groups (high and low L2 ability) to determine the effect of L2 ability in L1 and L2 speaking tasks, and to map brain regions involved in both tasks. The brain activation during task performance was determined using prefrontal cortex blood flow as a proxy, measured by functional near-infrared spectroscopy (fNIRS). People with low L2 ability showed much more brain activation when speaking L2 than when speaking L1. People with high L2 ability showed high-level brain activation when speaking either L2 or L1. Almost the same high-level brain activation was observed in both ability groups when speaking L2. The high level of activation in people with high L2 ability when speaking either L2 or L1 suggested strong inhibition of the non-spoken language. A wider area of brain activation in people with low compared with high L2 ability when speaking L2 is considered to be attributed to the cognitive load involved in code-switching L1 to L2 with strong inhibition of L1 and the cognitive load involved in using L2.

Highlights

Humans learn their first language naturally from their parents in parallel with lateralization of the brain
It was reported that the volume of white matter in the prefrontal cortex of the right hemisphere increases and neural bonds strengthen with L2 acquisition [4]
Density of both gray matter and white matter was revealed to have increased with L2 acquisition [5,6,7] patterns of brain activation were associated with age of L2 learning, task difficulty, and proficiency of L2 ability

Summary

Introduction

Humans learn their first language (hereinafter referred to as L1) naturally from their parents in parallel with lateralization of the brain. Antoniou et al [2] elucidated how the prefrontal cortex was involved in learning a second language (hereinafter referred to as L2). It was reported that the volume of white matter in the prefrontal cortex of the right hemisphere increases and neural bonds strengthen with L2 acquisition [4]. Density of both gray matter and white matter was revealed to have increased with L2 acquisition [5,6,7] patterns of brain activation were associated with age of L2 learning, task difficulty, and proficiency of L2 ability

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Discussion

Conclusion