Brain Activation in Response to Disgustful Face Images with Different Backgrounds

摘要

Previous studies have demonstrated tliat the stimulus of a fearful and disgustful face images lead to activation of neural responses in the medial temporal lobe. In particular, it was reported that seeing disgustful face image activated the insula area of brain. In these studies, no background images were used with facial stimuli. However, normal day-today images always have a background. Moreover, background images are considered important in art forms (painting, photography, and movies, etc.) for eliciting effective expressions. We assessed the effect of background images on brain activation by using functional magnetic resonance imaging (fMRI). During fMRI scanning, face images with background images were presented repeatedly to 8 healthy right-handed males. Facial stimuli comprised 5 photographs of a disgustful face selected from the Paul Ekman's database (Ekman and Friesen 1976). The background images comprised 2 photographs-one is worms and the other is a flower garden. It is thought that disgustful face images coincide with worms background image on the point of impression. After scanning, the subjects rated the impression created by the images on the Plutchik scale. Significant effects of the image of the disgustful face against the worms background minus that against the flower garden were assessed using a t-test and displayed as statistical parametric maps (SPMs) using SPM2 software. The results demonstrated activation of the right insula, and the image of the disgustful face against the worms background created a more disgustful impression than that against the flower garden. Therefore, the image of the face and the background together create the overall impression. The difference in the activation of the insula is possibly induced by the creation of this overall impression. This demonstrates the importance of background images in forming an impression of face images.