3-A-D-1-13. High frequency activities in the frontal cortices during observation of moral or immoral behaviors

Abstract

We measured MEG in twenty-one healthy subjects when they judged 120 duologue-scenes moral or immoral behaviors using a response of the left index (moral) or middle finger (immoral) movement. Sixty duologue-scenes contained aggressive or egoistic context of either character’s line, and the remainder were the same scenes with neutral or friendly context of both characters’ lines. These scenes were successively presented for 6.5 s in a random order with taking enough breaks. The mean reaction time for the response was approximately 4 s. Spontaneous MEG of 3 s prior to the response was analyzed by a spatial filtering algorithm method. The MEG when watching the duologue-scenes without any lines served as the baseline. As compared with the baseline, the power of high frequency activity (HFA, 22–100 Hz) was increased in the left occipital cortex from −2.5 to −0.5 s, and the right motor area from −1 to 0 s prior to the response for judgment of either moral or immoral behavior. When judging the scenes immoral behaviors, the augmented HFA was observed in the bilateral orbitofrontal and anterior cingulate cortices from −1.7 to 0 s, suggesting that the activations in these areas are related to aversion feeling and decision-making.