한국어-영어 이중 언어 학습 아동에서 제2언어 습득과 연관된 대뇌 영역 활성화 기전 = Neural Mechanism of Second Language Processing in Korean-English Bilingual Children

다국어 초록 (Multilingual Abstract)

Purpose To evaluate the neural mechanism of second language processing in Korean-English bilingual children using functional MRI (fMRI).
Materials and Methods The study was conducted on 20 Korean elementary school children who were learning English as a foreign language. fMRI was performed during short-passage comprehension tasks in Korean and English languages. We analyzed which brain areas were activated according to the language, English proficiency, and task difficulty.
Results Higher activities were observed in the dorsolateral prefrontal cortex, supplementary motor area, precentral gyrus, left basal ganglia, and left temporoparietal and occipital lobes during English comprehension than during Korean comprehension. The low English proficiency group showed higher activities than the high English proficiency group in the frontotemporal cortex, including the prefrontal cortex. Higher activities were observed in the right inferior frontal gyrus and right temporoparietal lobe during the English comprehension task of intermediate difficulty compared to that of low difficulty. However, the brain activities significantly decreased while performing a high-difficulty English task.
Conclusion Brain activities significantly increased during English comprehension in the lower English proficiency group while performing an intermediate-difficulty task. However, brain activation decreased when the task difficulty exceeded the moderate comprehension level. These results suggest that a proper level of education is important to learn a second language.

국문 초록 (Abstract)

목적 제1언어(한국어)~제2언어(영어) 이중 언어 학습 아동에서 기능적 자기공명영상(functional MRI; 이하 fMRI)을 이용하여 제2언어 습득과 연관된 대뇌 활성화 기전을 알아보고자 하였다.
대상과 방법 영어를 배운 적이 있는 초등학교 4~6학년(11~13세) 학생 20명을 대상으로 하였다. 상, 중, 하 난이도로 구분된 단문 이해 과제를 각각 한국어와 영어로 수행하는 동안 fMRI 데이터를 획득하였다. 언어별, 언어구사능력별, 난이도별로 나타난 대뇌 활성화 신호를 각각비교 분석하였다.
결과 영어 과제 수행 시 한국어 과제보다 등외측 전전두엽, 보조운동영역, 중심전회, 좌측 기저핵, 좌측 두정측두엽 및 후두엽 등에서 더 높은 활성화를 보였으며, 언어구사능력이 낮을수록 전전두엽을 포함한 전두측두엽 피질의 활성이 높게 나타났다. 중 난이도의 영어 과제에서 하 난이도의 과제보다 우측 하전두회, 우측 두정측두엽 등에서 더 높은 활성화를 보였으나, 상 난이도의 과제 수행 시 대뇌 활성 영역 및 정도가 현저히 낮게 나타났다.
결론 한국어에 비해 영어 과제를 수행할 때, 영어구사능력이 낮은 아동에서, 중 난이도의 영어 과제를 수행할 때 대뇌 활성화 범위가 넓고 정도도 높게 나타났다. 그러나 시험자의 이해도를 초과하는 과제 수행 시에는 대뇌 활성이 오히려 낮게 나타남으로써, 적절한 수준의제2언어 학습이 중요함을 알 수 있었다.

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