Replication of Prefrontal Asymmetry in Approach-Avoidance Motivation in fMRI

A large body of research suggests that approach-related emotional states are lateralized to the left prefrontal cortex (Harmon-Jones et & Gable, 2018). However, because affective motivation and valence have often been entangled in experimental designs, it is unclear which construct drives this laterality. In one fMRI study designed to dissociate motivation and valence, Berkman and Lieberman (2010) found that approach motivation was more left-lateralized than avoidance motivation in the dorsolateral prefrontal cortex (DLPFC), controlling for valence. Our study did not replicate this key finding from Berkman and Lieberman (2010). Furthermore, whereas Berkman and Lieberman (2010) found that individuals' trait approach motivation predicted the laterality of approach-related DLPFC activity, we found that trait approach motivation predicted the laterality of positive valence, controlling for motivation. Overall, our results do not provide any clear support for the 'textbook' model of affective motivation in the frontal lobes.