Task-dependent changes in cortical color representation measured by the functional MRI technique

Color perception has multiple aspects, such as categorical perception and the continuous perception of colors. Past studies on color information processing in the visual cortex have suggested that categorical color perception is processed mainly at higher-order visual areas, such as hV4 and VO, while more continuous color perception (color appearance) is considered to be processed in the early visual cortex, such as V1-3. The aim of this study is to report changes in cortical representation in the regions of interest in visual areas through the explicit manipulation of participants' tasks using identical color stimuli. Our results showed that cortical activity patterns changed from the diverted attention condition when participants performed a color task. The difference was smaller in the early visual cortex during color appearance judgments than during the color category task but was significant in higher-order visual areas (V3, hV4, and VO1/2). The differences in cortical activity patterns were evaluated by direct comparisons between brain activities, and the differences between color appearance and categorization tasks were more pronounced in the anterior part of the ventral cortex. In summary, color representation at the earlier level of the visual cortex under diverted attention is more similar to that observed during the color appearance judgment, while color representation in higher-order visual areas changes more significantly from the diverted attention condition when conducting the color evaluation tasks.