To test the hypothesis that activation asymmetries of the most
anterior parts of the prefrontal cortex may be related to
state-dependent regulation of emotion, spontaneous changes of
cortical activation asymmetries from one session to a second
one were related to spontaneous mood changes in two large samples
(ns = 56 and 128). The interval between sessions was
2 to 4 weeks. Results show that mood changes specifically covary
with changes of EEG asymmetry at the frontopolar electrode
positions, but not with changes at other locations (dorsolateral
frontal, temporal, and parietal). Anxiety, tension, and depression
were found to decrease when frontopolar activation asymmetry
shifted to the right. Taking the new findings into account may
contribute to the refinement and extension of theories on EEG
laterality and emotion.