幾何圖形歸類判斷作業的認知行為表現與神經活動區域

Cognitive Behaviors and Neural Bases of Geometrical Categorization

本研究藉由行為實驗與腦功能核磁造影探討幾何圖形歸類之判斷作業的認知行為表現與神經活動區域。結果發現，概念類別、正/非例，和典型性會交互作用地影響反應時間，不論哪一種變因的效果都不是跨情境一致的，即使典型例的反應時間也未必在所有情況下都較非典型例來得短，可能因資料分析限定在正確率達98％的「三角形」與「四邊形」概念類別所致。而正/非例和典型性都未顯現特定腦區的差異，僅從事「三角形」與「四邊形」判斷作業時，均會產生後側扣帶迴的抑制反應，且兩概念類別所涉及的後側扣帶迴區域有明顯地重疊，雖然兩者也有引發不同的腦區，如「四邊形」作業還會抑制上顳葉（BA41）與前運動皮質（BA6）的活動，而「三角形」作業則無。上述結果意味著，幾何圖形概念的提取與比對可能獨立於圖例的處理，但都涉及到後側扣帶迴。

The study aimed to examine cognitive behaviors and the corresponding brain areas via functional magnetic resonance imaging (fMRI) while people categorize geometrical figures. The results showed categorization tasks, positive/negative examples, and typicality interactively influenced reaction times. It indicates that the effects of one variable were not constant across different variables. For instance, the reaction times (RTs) in the typical examples were not quicker, in all conditions, than that in the atypical examples. It may be the results of filtering out the accuracy below 98%. However, the corresponding brain areas were only found for the categorization tasks. Both “Triangles” and “Quadrangles” categorization tasks deactivated the posterior cingulated cortex and there were significantly overlapped areas in BA31. “Quadrangles” categorization task additionally deactivated superior temporal lobes (BA41) and premotor areas (BA6) but “Triangles” did not. The results suggested the retrieval of geometrical concepts and the comparison to the stimuli examples would be associated with the posterior cingulated cortex, which may be independent from the processing of stimuli examples.