The Effects of Oxytocin on Social Touch: an fNIRS-based Study

A randomized double-blind placebo-controlled mixed experimental design with three arms (intranasal oxytocin administration vs. oral oxytocin administration vs. placebo administration, each with 60 subjects) will be employed in the current study. 35 minutes after treatment subjects will be applied two different types of pleasant touch (social massage vs. caress-like stroking) to their calf. After each applied touch stimulation session, the subjects will be asked to rate their subjective experience of the touch including the perceived pleasantness, arousal, intensity and payment. The neural basis of touch processing will be measured via simultaneously acquired fNIRS together with skin conductance responses and the electrocardiogram recording. Blood samples will be taken before and after the treatment as well as after each run session to measure plasma oxytocin levels to explore the associations with primary outcome measure (the behavioral and neural measures of touch processing). Mixed-measure analysis of variance (ANOVA) with treatment as between-subject factor and condition as within-subject factor will be used to investigate oxytocin effects on social touch processing.

To control potential confounding effects across groups, before the experiment all participants will be asked to complete a range of Chinese versions of validated questionnaires on personality, traits, attitude towards interpersonal touch and sensitivity to reward: Autism Spectrum Quotient (ASQ), Beck Depression Inventory II (BDI), State-Trait Anxiety Inventory (STAI), the Cheek and Buss Shyness Scale (CBSS), the Adult Attachment Scale (AAS), the Childhood Trauma Questionnaire (CTQ), social touch questionnaire (STQ), Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), Sensory Over-Responsivity (SensOR) Scales and the Interpersonal Reactivity Index (C-IRI). And associations between questionnaire scores (especially the ASQ and STQ scores) with primary outcome measure will be explored to investigate modulatory effects of autistic traits. Additionally, to control for potential confounding effects of treatment on mood across the experiment, the Positive and Negative Affect Schedule (PANAS) will be administered immediately before and 30 minutes after the treatment. Participants will also complete the PANAS after each type of touch condition to further measure the modulatory effects of stroking touch and massage on mood.