Affective disposition and cognitive processing in dysphoria: a time-frequency EEG study
To date, affective disposition and cognitive processing of emotional stimuli in individuals with depressive symptoms have not been fully explored within the same framework. Time-frequency analysis of electroencephalographic activity allows to disentangle the brain's parallel processing of information. The present study employed a time-frequency approach to simultaneously examine affective disposition and cognitive processing during the viewing of emotional stimuli in dysphoria. Time-frequency event-related changes were examined during the viewing of pleasant, neutral and unpleasant pictures in 24 individuals with dysphoria and 24 controls. Affective disposition was indexed by delta and alpha power, while theta power was employed as a correlate of cognitive elaboration of the stimuli. Cluster-based statistics revealed a centro-parietal reduction in delta power for pleasant stimuli in individuals with dysphoria than controls. Also, dysphoria was characterized by an early fronto-central increase in theta power for unpleasant stimuli relative to neutral and pleasant. Instead, controls were characterized by a late fronto-central and occipital reduction in theta power for unpleasant stimuli relative to neutral and pleasant. The present study granted novel insights on the interrelated facets of affective elaboration in dysphoria, mainly characterized by an hypoactivation of the approach-related motivational system and a sustained facilitated cognitive processing of unpleasant stimuli.