Inter-Subject Neuronal Correlation during Natural Article Reading

過去針對閱讀理解的腦造影研究多半使用嚴格控制且簡化過的閱讀材料，並以迥異於日常閱讀情境的方式呈現給受試者。本實驗中，我們讓受試者以自然的方式閱讀整篇文章，並以功能性磁振造影（functional magnetic resonance imaging, fMRI）揭露對文章的用字遣詞與文字排列方式有所反應的腦區。具體而言，我們讓受試者閱讀選自紐約時報（新聞）與讀者文摘（故事）之英文原文經由專業譯者或翻譯軟體產生的兩種中文譯文。我們計算閱讀同一篇文章的各受試者腦部活動的相關係數。藉由本實驗的設計，我們得以探討一般情境下腦部活動因文體（紐約時報對上讀者文摘）或翻譯方式（人類對上機械翻譯）的差異而導致的腦部活動變化。 我們發現fMRI訊號的受試者間相關係數的空間分布情形確實受到文體與翻譯方式的調控。不論閱讀何種文體或翻譯方式的文章，我們都能在上、中顳葉皮質觀察到較低的受試者間相關係數（inter-subject correlation, ISC），同時能在中央溝前後的背內側皮質觀察到較高的ISC值。 進行文體間的對比後，發現右側前顳葉區域的ISC值在閱讀新聞時比閱讀故事時低；翻譯方式之間的對比則顯示右側下方額葉皮質在閱讀機械翻譯文章時的ISC值較高。綜上所述，當受試者需要使用較高的閱讀整合能力以理解一篇文章，右半腦的活動便會顯著提升。未來的神經語言學家若要進一步揭露自然語言裡解所牽涉的腦部處理歷程，本實驗所採用的方法與觀察到的結果可能有所助益。Most neuroimaigng studies on reading comprehension use well-controlled simplified materials and show them in a way different from natural reading. In this study, we used functional magnetic resonance imaging (fMRI) with texts presented in a natural way to reveal brain areas sensitive to word choices and arrangements. Specifically, articles from the New York Times and the Reader’s Digest translated either by human or machine were presented to participants. The correlation of brain activity across participants during article reading was calculated. This experiment design allowed us to study how the common brain activity changes between text genres (New York Times vs. Reader’s Digest) and translations (human vs. machine translations). We found that spatial distributions of correlated fMRI signal across participants were modulated by article genre and translation. Across text genres and translation, we found low inter-subject correlation (ISC) at superior and middle temporal cortices and high ISC at dorsal medial pre- and post-central cortices. Comparing between text gernes, we found ISC values at right anterior temporal lobe were lower during news article reading than during fictional article reading. Comparing between translations, increased ISC values were observed at right inferior frontal cortex when reading texts translated by machine. Taken together, the right hemisphere is more activated when a higher demand in the reading comprehension capacity is required. The experimental approach and results described in this study may be useful for neurolinguists to further elucidate brain processes related to natural language comprehension