The aim of the present study is to examine whether the neuropeptide oxytocin (OXT) influences social reward processing and whether the effects are context- and sex-dependent.

In a double-blind, randomized, placebo-controlled, between-subject design healthy volunteers will receive either oxytocin or placebo nasal spray (40IU in 10 puffs).

Subjects will come to the experiment in pairs (two friends of the same sex). 45 min after drug administration, the two subjects will simultaneously undergo a social reward task - during the task, functional magnetic resonance imaging (fMRI) data will be acquired from one of them. During the social reward task subjects will be asked to rate the valence and arousal of emotional pictures in three different conditions: alone, share with a stranger and share with their friend.

Before treatment, subjects will complete a range of validated questionnaires to control for potential confounders, such as level of depression (assessed using the BDI) and to explore associations between relevant personality factors and treatment effects, such as adult attachment style (assessed using the AAS).

Inclusion Criteria:

• Healthy subjects without past or current psychiatric or neurological disorder, right-handed, had normal or corrected-to normal vision.

Exclusion Criteria:

• self-reported medication use, substance abuse, and presence of medical or psychiatric disorders