Oxytocin enhances processing of positive versus negative emotional information in healthy male volunteers

Animal studies have shown the role of oxytocin in affiliation and attachment, and recent evidence suggests that oxytocin is also involved in human models of approach behaviour, possibly by modulating the processing of emotionally valenced stimuli. Although oxytocin administration has been reported to decrease neural responses to facial emotional information, the effects on a wider range of behavioural measures of emotional processing shown to be sensitive to antidepressant manipulation have not been examined. The aim of this study was to investigate whether intranasally administered oxytocin affects the processing of positive and negative affective information in healthy male volunteers across tasks measuring attention, perception and memory. Twenty-nine male healthy volunteers were randomly allocated to receive a single dose of oxytocin nasal spray (24 UI) or placebo. 50 min later, participants completed a battery of psychological tests measuring emotional processing. A single dose of intranasally administered oxytocin slowed reaction time to correctly identify fearful facial expressions and reduced the misclassification of positive emotions as negative ones. These effects occurred in the absence of significant differences in subjective ratings of mood and anxiety. These results suggest that oxytocin modulates emotion processing in healthy male volunteers. This action may contribute to the emerging role of the neuropeptide in promoting affiliative and approach behaviours by reducing the salience of potentially ambiguous and threatening social stimuli.