The main aim of the study is to investigate whether orally administered oxytocin (24IU) could modulate females' neural and behavioral responses to affective stimuli including emotional faces and affective scenes.

All subjects will complete a series of questionnaires firstly to control for possible pre-treatment confounders in terms of personality traits and mood: Beck Depression Inventory-II (BDI), Autism Spectrum Quotient (ASQ), Liebowitz Social Anxiety Scale (LSAS), State-Trait Anxiety Inventory (STAI), Childhood Trauma Questionnaire (CTQ), the Second Version of Social Responsiveness Scale(SRS-2), Positive and Negative Affect Schedule (PANAS). PANAS is administered before and after oral administration and after functional magnetic resonance imaging (fMRI) scanning. In the current double-blind, between-subject, placebo-controlled study 80 healthy female subjects will be recruited and receive oral administration either oxytocin (24IU) or placebo. Blood samples are collected twice before and 30 minutes after oral administration to assess the plasma OXT concentrations change. 45 minutes after oral administration subjects will be required to finish fMRI scanning including resting-state fMRI task, emotional face task (happy, fear, angry and neutral faces), affective scene task (NAPS, Nencki affective picture system, positive, neutral, and negative-valence scenes). After fMRI scanning, subjects will be required to rate valence, intensity, and arousal responses (Likert scale, 1-9 ratings) to the emotional and affective stimuli are presented during fMRI scanning.