EEG activity over frontal regions during positive and negative emotional experience

It has been shown that frontal EEG activity has potential for estimating emotional state. When one emotional state changes into another, it is likely that the time course and dominance of emotion play an important role in this process. Therefore, the present study investigated the correspondence between emotional state, such as pleasantness or unpleasantness, and EEG activity. In addition, we used different sensory modalities of emotional stimuli, such as odor and image, to examine whether EEG activity fluctuates with the time course of emotion. Fifteen university students participated in both the image and odor stimulus sessions. They were instructed to adjust a dial to rate their subjective emotional intensity during the period between the onset of image/odor presentation and the offset of a blank screen presentation. Standard 21 channel electroencephalograms were recorded and analyzed, after which laterality, coherence and frequency fluctuation of the alpha band of frontal EEG signals were compared among control, pleasantness and unpleasantness conditions. Our results indicated that both the laterality model and the frequency fluctuation model were able to estimate emotional state from frontal alpha band EEG activity. However, the sensory modality of the stimulation influenced the laterality of frontal cortical activity, as indicated by a difference in the laterality index between the image and odor sessions.