Mounting evidence indicates that the intranasal administration of the neuropeptide oxytocin has prosocial effects. However, the neural substrates of these effects are still unclear. The investigators hypothesized that a single dose administration of oxytocin should increase empathogenic and affiliative responses and that these effects are mediated by an increased insula activity.

Inclusion Criteria:

• Healthy male volunteers
• In a heterosexual relationship

Exclusion Criteria:

• Current or past psychiatric disease
• Current or past physical illness
• Psychoactive medication
• Tobacco smokers