Task-related dissociation of EEG β enhancement and suppression.

Previous investigations of EEG β processes can be divided into two categories: one in which β enhancement is obtained and one in which β suppression is obtained. The current study investigated the β band range (14-30Hz) by subdividing the signal into 2Hz sub-bands. We presented participants with photographs of faces expressing happy, angry, sad or neutral expressions under two primary tasks in which participants judged the emotion the individual was expressing, or how the way the other person feels makes the participant feel. Results revealed a pattern of both β suppression and enhancement that appeared to depend on whether the task required first-person emotional experience (self-task) or perspective-taking (other-task). Specifically, the self-task was associated with enhancement while the other-task was associated with suppression. While some previous research has reported β enhancement to emotion-inducing stimuli, other research has reported β suppression in tasks also associated with mu suppression. To our knowledge, the current data are the first to reveal both β enhancement and suppression within a single experiment and suggests a neurocognitive dissociation of enhancement and suppression within the β band range.