Measurement of visual evoked potential by facial perception

This study focuses on the brain information processing in the facial perception. fMRI(functional Magnetic Resonance Imaging) and PET(Positron Emission Tomography) are used in the past study of the facial perception. However, these methods can not give the temporal information about the processing of the brain. These methods give only spacial information of the activated area in the brain. In this study, we measured the ERP (event related potential) in the facial perception to investigate the electrical activity in the brain of facial perception. Three tasks of the facial perception were conducted and each ERP was measured at four sites of the brain. First task is the simple face presentation. Second one related to the category classification of the face. The last task related to the visually search of the target face. In the third experiment, four face images are presented, and the subject searches whether there is a target or not. In the second experiment, P300 response was appeared. P300 caused by presenting the target stimulation and non-target stimulation. In the third experiment, the peak tended to be seen between 200 and 300ms. It is said that a right hemisphere is more dominant than a left hemisphere of the brain in the facial perception. In this experiment, the reaction between 100 and 200ms from the right temporal site was larger than that of the left. Therefore, it is thought that the reaction related to the facial perception appears at this time.