AFFECT, FACIAL EXPRESSION, AND BRAIN ASYMMETRY

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The research proposed in this application is designed to continue our studies of cerebral asymmetry and its relation to emotion and depression. Studies will be conducted on the relation between facial signs of emotion elicited by brief film clips and patterns of concurrently recorded brain activity. A methodological experiment will be performed during the first year of this project period which is designed to validate a procedure for removing muscle tension artifact from the ongoing EEG. The experiments which examine EEG during facial signs of emotion will broaden the range of emotions which have been studied. We will compare a negative emotion associated with withdrawal and one more commonly associated with approach (anger) in order to shed light on whether the basis for affective lateralization is hedonic tone or approach/avoidance. The role of facial expression in contributing to the EEG asymmetries associated with affect will be studied in order to more precisely specify which components of emotion are most directly reflected in scalp recorded brain activity. This will be accomplished by comparing EEG asymmetry in situations where facial signs of emotion and a measure of real-time self-report are consistent versus inconsistent. Asymmetries which differentiate between depressed patients and controls will also be explored. Differences between these groups in patterns of EEG asymmetry will be examined during resting conditions as well as in response to both cognitive and affective challenges. Relations between activation asymmetries in anterior and posterior cortical regions will be compared in these groups to replicate and extend our recent findings which suggest that depressed subjects show inverse relations between activation asymmetries in these regions. Differences between these groups in emotional response will be explored to determine whether elicitors which produce a range of different emotions in controls are more likely to produce sadness in depressed subjects. The groups will also be compared on EEG and self-report when facial behavior indicates that the same emotion is present, in order to determine, once an emotion is elicited, whether the pattern of EEG asymmetry and self-report is the same in these groups. The proposed studies will directly contribute to understanding emotion and affective disorders.