Abstract
In this study we used the electroencephalograph (EEG) dipole tracing method to analyze the visual and emotional evoked potentials (VEEPs) triggered by emotional stimuli induced by pictures of fear, sadness and happiness selected from the International Affective Picture System. We hypothesized that if we used the emotional pictures as triggers for averaging the EEG, we could determine VEEPs, and dipoles could be estimated in the visual cortex as well as in the areas related to the picture-induced emotions. We found the VEEP components elicited by fearful and sad stimuli were quite similar and there were no differences in the root mean square values of the positive waves, P1 and P2, in these two stimuli. However, the VEEP elicited by the happy stimulus had a significantly different amplitude compared to the fearful and sad stimuli. Different amplitude components of VEEPs between negative and positive emotions might be caused by differences in the processing of activations. The negative emotions of fear and sadness activated the amygdala in parallel with the visual cortex immediately after the stimuli; and at a later time period the anterior cingulate cortex was activated for conscious awareness of the negative emotions. A simple happy stimulus does not need parallel activation of the amygdala and anterior cingulate cortex, along with activation of the visual cortex. We suggest that parallel processing in the visual cortex and amygdala might serve to rapidly evaluate stimuli, in readiness for the conscious awareness of negative emotions.
