Emotion and Brain Oscillations: High Arousal is Associated with Decreases in Alpha- and Lower Beta-Band Power.

The study of brain oscillations associated with emotional picture processing has revealed conflicting findings. Although many studies observed a decrease in power in the alpha- and lower beta band, some studies observed an increase. Accordingly, the main aim of the present research series was to further elucidate whether emotional stimulus processing is related to an increase or decrease in alpha/beta power. In Study 1, participants (N = 16) viewed briefly presented (150 ms) high-arousing erotic and low-arousing people pictures. Picture presentation included a passive viewing condition and an active picture categorization task. Study 2 (N = 16) replicated Study 1 with negative valence stimuli (mutilations). In Study 3 (N = 18), stimulus materials of Study 1 and 2 were used. The main finding is that high-arousing pictures (erotica and mutilations) are associated with a decrease of power in the alpha/beta band across studies and task conditions. The effect peaked in occipitoparietal sensors between 400 and 800 ms after stimulus onset. Furthermore, a late (>1000 ms) alpha/beta power increase to mutilation pictures was observed, possibly reflecting top-down inhibitory control processes. Overall, these findings suggest that brain oscillations in the alpha/beta-band may serve as a useful measure of emotional stimulus processing.