抄録
Although recent advances in the computer graphics techniques allow us to generate photo-like images, we can distinguish them from real photos. This suggests that an ability to detect the differences between real photo and photo-like images may be embedded in our cognitive system. In this study, we investigated the cortical mechanisms underlying this ability by means of fMRI. Color photographs of human face were modified into painting-like images in five steps. To characterize physical properties of stimulus, the spatial frequency, and the mean changes in color and luminance of each image were calculated. Participants were required to classify the images into one of the five steps(1:photo,5:painting-like image) during fMRI scanning. We found several brain regions, including middle occipital gyrus, middle temporal gyrus, temporo-parieto-occipital junction, parieto-occipital sulcus (POS), fusiform gyrus (FG) and middle frontal gyrus (MFG), were activated during the task. The detailed analysis showed that the activity in the POS and MFG was enhanced when participants evaluate the presented images as more painting-like, while activation in the other regions was correlated with the physical properties of images. These results suggest that the POS-MFG. network may play a crucial role in the detection of differences between real photos and photo-like images. This study was supported by Academic Frontier Project for Private Universities:"Brain Mechanisms for Cognition, Memory and Behavior"at Nihon University:matching fund subsidy from MEXT. [J Physiol Sci. 2008;58 Suppl:S144]
