Individuals with high trait anxiety show stable anxiety proneness even in the absence of real threat, which could be a result of intrinsic hyper-connectivity in the defensive systems. In the present study, healthy subjects' trait anxiety levels will be assessed by the sub-trait inventory of the State-Trait Anxiety Inventory. Then two experiments using resting-state fMRI technique will be conducted to first map how hubs in the defensive systems organized in high anxious individuals in a stimuli-free situation (Experiment 1) and then we will examine the modulatory effect of the intranasal administration of oxytocin on functional connectivity in these independently defined defensive networks (Experiment 2).