Effects of lateralized presentations of faces on self-reports of emotion and EEG asymmetry in depressed and non-depressed subjects.

Recent data suggest that individuals with affective disorders show anomolies on various measures of cerebral lateralization and hemispheric activation. In this study, EEG was recorded from left and right frontal and parietal scalp regions during left and right visual field and foveal presentations of happy, sad and neutral faces in 10 depressed and 10 non-depressed subjects. The sample was selected from a student population on the basis of scores on the Beck Depression Inventory. Faces were presented for 8 seconds and EOG was used to exclude trials associated with eye movements. Alpha activity from each of the leads during the middle 6 seconds of each trial was extracted for analysis. In addition, subjects were asked to rate each face on the degree to which it depicted various emotions, as well as the degree to which they experienced various emotions in response to each presentation. The results indicated that non-depressed subjects report more happiness in response to RVF compared with LVF presentations of the identical faces while depressed subjects show the opposite pattern. Frontal EEG alpha asymmetry paralleled the subjective ratings of happiness for both groups and accounted for more than 50% of the variance in self-reports of this emotion. Parietal asymmetry showed little relationship to subjective reports of emotion but did show systematic differences as a function of stimulus location, primarily due to changes in right parietal alpha. Finally, depressed subjects showed reciprocal relationships between frontal and parietal asymmetry while non-depressed subjects showed a positive relationship between asymmetry in these regions. The implications of these data for cognitive dysfunction in depression are discussed.