Mental rotation of alphabet characters affects the face-sensitive N170 component

Face-sensitive N170 component of event-related potential is sensitive to face inversion, which has been defined as the face-inversion effect. Moreover, a previous study suggested that similar to the face-inversion effect of the face-sensitive N170 affected by mental rotation of the face, object-related N170 of three-dimensional objects was also affected by the mental rotation of two-dimensional objects. The purpose of the present study was to compare the relationship between face-sensitive N170 during face perception (upright and inverted faces) and object-related N170 during character perception (normal and mirror version for alphabet characters). The results indicated that the latency of N170 for mirror version for alphabet characters was significantly longer than that for normal version for alphabet characters, and the latency of N170 for inverted faces was significantly longer than that for upright faces. Therefore, the results of the present study clearly indicate that face-sensitive N170 components are related to the mental rotation of normal and mirror version for alphabet characters. These results suggest the novel possibility that face-sensitive N170 latency can be used as a biomarker for mental rotation and that mental rotation is related to the fusiform area as a neural generator of N170 in the human brain.