Emotion and attention effects as revealed by brain oscillations.

Neural oscillations are thought to represent a fundamental brain mechanism and are widely used to study cognitive processes. In comparison, less is known about emotion processing, which so far yielded an ambiguous pattern of find-ings. To further advance understanding, a series of experiments examined emo-tional stimulus processing in different task contexts. In the first experiment, 16 participants viewed erotic and romantic pictures, differing in stimulus arousal and inter- trial interval (~1 vs. ~8 s). In one condition, participants passively viewed the pictures, in the other, they performed an active picture categoriza-tion task. The processing of erotic compared to romantic images was associated with a decrease in power in the alpha- and lower beta- band in posterior and an-terior sensor clusters between 600- 1000 ms post- stimulus. The finding was con-firmed across conditions, different quantifications of power, i.e., absolute and decibel change to baseline, and independent from baseline activity. Follow- up experiments revealed similar findings across studies including negative stimulus materials, i.e., mutilation pictures, and an explicit counting rather than reaction time task. These findings suggest that power decreases in the alpha- and lower beta- band are a reliable phenomenon of emotionally significant stimulus ma-terials (pleasant and unpleasant). Results are discussed with respect to the hy-pothesis that alpha- and lower beta- band activity may reflect cortical activation associated with emotional stimulus significance and compared to established event related potentials.