Oxytocin Effects On Neural Mechanisms Underlying Affective Touch

Affective touch acting as an important way of social interactions,plays a crucial role for social communication and bonding relationships.The abnormalities of affective touch processing are common in psychiatric disorders such as autism.Therefore it is of great significance to explore the possible interventions on modulating affective touch processing.The neuropeptide oxytocin(OT)has been shown to be associated with social bonds and interactions,which seems quite similar to the beneficial effects on social relationships of affective touch.And affective touch has been shown to modulate the oxytocin release.However,the related researches about the interactions between OT and affective touch are rare and mainly focused on pleasant interpersonal touch processing.So no studies directly work on how OT will modulate the individual responses to tactile stimuli with different valence.In a functional fMRI study using placebo-controlled within-subject design,50 healthy participants were asked to concentrate on the positive and negative touch stimuli as well as control neutral condition and then rated the perceived pleasantness of each touch.Results showed that on the behavioral level,subjects rated the positive touch as most pleasant relative to other two conditions and most unpleasant to negative touch,indicating the experimental manipulation was effective.After intranasal oxytocin treatment,individual behavioral ratings across all touch conditions marginally increased compared with placebo treatment,and the post hoc analysis showed OT’s behavioral modulated effects were most sensitive to negative touch.On the neural level,results showed a significant main effect of valence that different touch activated different regions.OT significantly increased neural responses in oribitofrontal cortex(OFC)to all touch conditions.Besides,OT also significantly increased anterior insula activation to negative touch(vs.neutral touch).Personal autistic traits(including individual altitudes towards touch)can influence OT’s effects on negative touch.Results showed OT only augmented the behavioral ratings of negative touch and the activation in posterior cingulate cortex(PCC)to negative touch among subjects with low AQ scores.The psychophysiological interactions analysis found OT generally decreased the functional connectivity between OFC and middle cingulate cortex(MCC),which was mainly driven by the effects of OT on the functional connectivity to positive touch.Overall,this study emphasizes on OT’s modulated effects on the neural mechanism of affective touch and results suggested that OT could augment personal responses to positive and negative touch with the modulated effects on reward system and salience network.This study provided positive experimental evidence for clinical applications of intranasal oxytocin to improve affective touch processing in mental disorders,particularly autism.