P889: Electrical impedance tomography (EIT) of epileptic seizures in rat models – a potential new tool for diagnosis of seizures

activity without severe motion restriction. Therefore, NIRS has been applied for exploring cerebral functions in various populations. Our future research goal is to objectively evaluate the perception of facial emotion in people with profound multiple disabilities. Thus, we examined neural correlates of facial expression changes in normal adults by using NIRS. Methods: 12 female adults participated in this experiment. The three cycles of the block design composed of 40-second rest period and 30-second task period were done in each condition for NIRS measurement. Participants were asked to view passively the fruit and face images. This experiment was done in the following conditions: 1) Face recognition: a fruit image in the rest period and a neutral face in the task period. 2) Eye-closed facial expression: neutral face images in the rest period and facial expression change into eyes closed face from eyes open face (neutral face) in the task period. 3) Happy facial expression: neutral face images in the rest period and facial expression change to a happy face from a neutral face in the task period. 4) Angry facial expression: neutral face images in the rest period and facial expression change to an angry face from a neutral face in the task period. NIRS was recorded from 66 channels in frontal and bilateral temporal area. Mean values of Oxy-Hb at each channel was compared between 10-second before and 30-second during task period in all conditions. Results: Regardless of condition, Oxy-Hb significantly increased in right temporal area. On the other hand, Oxy-Hb in superior frontal area significantly decreased under all facial expression conditions, especially angry and happy face. In left inferior frontal area, a decrease of Oxy-Hb was observed in only happy face. Conclusions: Oxy-Hb decrease in frontal area might be related to facial movement since such a phenomenon was robustly observed in angry and happy face images with larger motion. On the other hand, difference of positive and negative facial expressions might be able to explain by deactivation in left inferior frontal area.