ISSN : 1226-9654
언어적 자료의 심상화 특성과 비언어적 자료의 언어화 특성이 의도적인 기억 부호화에 미치는 영향을 알아보고자 사건-유관 fMRI 연구를 수행하였다. 부호화단계에서 구체어, 대상 그림, 그리고 추상패턴을 의도적으로 학습하도록 요구하면서 fMRI 영상을 구하였고 인출단계에서 재인판단검사를 실시하였다. 재인 수행 결과 그림, 구체어, 추상패턴의 순으로 기억 수행이 우수하였다. 상측 전두회(BA 6), 상측 두정피질(BA 7), 그리고 내측두피질의 세 ROI에서 신호변화율을 분석한 결과, 상측 전두회에서는 추상패턴만이 좌반구보다 우반구에서 더 큰 활성화를 보였고 구체어와 그림은 반구 차이를 보이지 않았으며 추상패턴은 우반구에서 구체어와 그림보다 더 큰 활성화를 보였다. 상측 두정피질에서는 세 학습자료 모두 반구 차이를 보이지 않았고 추상패턴은 구체어와 그림보다 더 큰 활성화를 보였으며, 내측두피질에서는 세 학습자료간 차이와 반구차이가 모두 관찰되지 않았다. 학습자료간 대비를 수행한 결과, 추상패턴은 신호변화율 분석 결과와 유사하게 상측 전두회에서는 구체어와 그림에 비해 우반구에서 더 큰 활성화를 보였고 상측 두정피질에서는 구체어에 비해 양반구에서, 그림에 비해 우반구에서 더 큰 활성화를 보였다. 그러나 내측두피질에서는 학습자료간 대비 결과가 신호변화율 분석 결과와 상이하였는데, 구체어와 그림은 모두 추상패턴에 비해 양반구에서, 그림은 구체어에 비해 우반구에서 더 큰 활성화를 보였다. 전반적으로 구체어와 그림의 활성화패턴은 서로 유사하였으며 추상패턴과는 공통적으로 상이한 활성화패턴을 보였는데, 이러한 결과는 자료-특수 편측성 가설보다는 부호-특수 편측성 가설을 지지하는 것으로서, 기억 부호화의 신경기전이 학습자료의 심상화와 언어화 가능성에 따라 달라진다는 것을 시사하였다.
To investigate how the mechanisms of memory encoding were influenced by the verbalizability of nonverbal material and the imageability of verbal material, an event-related fMRI study was performed. Subjects were asked to intentionally memorize the mixtures of concrete words, object pictures, and abstract patterns and then perform recognition judgement test. Recognition scores revealed the superior accuracy for pictures and the worst accuracy for abstract patterns. Analyses of signal change ratio at the superior PFC(BA 6), superior parietal lobe(BA 7), and medial temporal lobe revealed right-lateralized frontal activation during abstract pattern encoding, no lateralized frontal activation during word and picture encoding, and higher right-frontal activation during abstract pattern encoding than word and picture encoding. No lateralized parietal activation during encoding was observed on all types of learning materials, and higher bilateral-parietal activation during abstract pattern encoding than during word and picture encoding was observed. No lateralized, nor differential MTL activation during encoding was observed on all types of learning materials. Analyses of contrast among learning materials revealed similar activation patterns at superior PFC and superior parietal lobe but different activation patterns at MTL, showing higher bilateral-MTL activation during word and picture encoding than during abstract pattern encoding as well as higher right-MTL activation during picture encoding than during word encoding. The overall bilateral activation patterns of words were similar to those of pictures, but activation patterns of words and pictures were different from those of abstract patterns. The data support the code-specificity rather than material-specificity hypothesis and indicate that the neural mechanisms of intentional memory encoding were dependent on the types of learning materials.
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