マンガの文脈に基づいて色を想起する際の脳活動

Brain Activations during Retrieval of Colors Based on the Context of Cartoons

左右の紡錘状回に色覚中枢があるが，色の想起過程は不明である。ストーリーを伴うマンガと共感課題を用いてこの領域の活動をfMRIで調べたところ，馴化効果は不自然な反転色を含む条件に限られ，モノクロでもカラーバーの反応レベルを維持した。また，1ページで十分な文脈を伴うマンガをモノクロで先に提示すると，カラー提示と同等の反応が見られ，共感度と合致した。以上の結果は，文脈に基づいて色が想起されたことを示唆する。

Abstract

The color center exists in the bilateral fusiform gyrus, but it is unknown whether this region also functions when one retrieves color information through the context of a story. To compare the effects of presentation condition/order between color and monochrome on activations in the color center, we used high-quality cartoons with a full story. We hypothesize that retrieval of colors based on the context can be much more than color retrieval through object vision. The participants performed two sets of an empathy task while their brain activations were quantified by functional magnetic resonance imaging. While color-selective activations were observed in the bilateral fusiform gyrus, habituation effects were observed only under the condition in which unnatural inverted colors were used. We confirmed that the responses of these regions to cartoons in monochrome were at the control level of color-bars even for second-half scanning runs. Moreover, when a full story cartoon on one page was presented first in monochrome, strong activations were elicited in the bilateral fusiform gyrus, which demonstrated an interaction effect similar to that of the degree of empathy. These results indicate that colors were retrieved in the brain based on the context of a cartoon.

(Received 5 September, 2022; Accepted 7 November, 2022; Published 1 February, 2023)