Oxytocin (OXT), a neuropeptide produced in the hypothalamus, is a key modulator of complex socioaffective responses including affiliation, social approach and attachment, stress and anxiety. Subjects receiving an intranasal spray of OXT (8 IU or 13.44 mg; Syntocinon-spray; Novartis, Switzerland) .

Placebo contains all ingredients except for the peptide in three puffs of 1.33 IU per 2.24mg nostril.

intranasally administrated

Using seed-based and network level functional connectivity analysis, as well as graph theory analysis , functional network organization in brain under eight minutes resting state will be detected and compared between oxytocin and placebo group.

Friend or Foe Task is used to measure the verbal versus nonverbal emotional judgement of subjects. Both the response of subjects and the brain activity are recorded in the task. How oxytocin influences the relationship between subjects' behavior and representation pattern of emotional judgement will be investigated through RSA(representation similarity analysis) of brain pattern.

Two-Stage Decision Making Task is used to measure the model-based and model-free decision making process of subjects. The degree of model-based will be calculated by Computational modelling of Subjects' decision making process, and entering as modulation parameter in the OT effect on dynamic brain seed-based and network-based connectivity pattern.

The functional brain activity in resting state, emotional judgement and decision making task will be compared. Both the functional segregation and integration will be measured using graph theory and network connectivity analysis to discover the OT effect on brain network organization across multiple cognitive states.