Right frontal lobe activation and right hemisphere performance. Decrement during a depressed mood.

TLDR: For instance, this paper found that depressed mood is characterized by asymmetrical EEG activation over the frontal lobes, with relatively greater activity in the right frontal region than the left frontal region.

Abstract: • Evidence from psychiatric patients has suggested that depressive affect may coincide with a decrement in the functioning of the right cerebral hemisphere. We have observed that college students who reported greater depression also reported less vivid imagery. Students undergoing experimental induction of depressive and euphoric moods in the laboratory showed an auditory attentional bias and impaired imagery during the depression condition, while their arithmetic task performance was unchanged. A second mood-induction experiment indicated a depressed mood to be characterized by asymmetrical EEG activation over the frontal lobes, with relatively greater activity in the right frontal region. These observations suggest that anterior regions of the brain may modulate the differential effects of emotional arousal on the information-processing capacities of the cerebral hemispheres.