The Modulations Of Intranasal Vasopressin On Human Affinitive Behaviors And Related Neural Signatures

Arginine vasopressin(AVP)is a neuropeptide composed by 9 amino acids,which is also known as hypophyseal-vasopressin.Early rodent and primate studies demonstrated that AVP is a powerful regulator for pair bonds(reproduction-related behaviors)and caring offspring(paternal behaviors).With the advancement in research technology,AVP is also found to affect human complex social behaviors.The current study mainly concerned about functioning of AVP on the human social bonding.We adopted adult and infant facial expressions as stimuli in two studies respectively,combining with intranasal AVP administration,ERP and fMRI techniques to investigate the functions of AVP and the related potential neural signaturesThe aim of study 1 was to examine the effects of AVP on human pair bonds.Specifically,we tried to investigate how AVP affects the processing of same-and other-gender facial expressions among nulliparous males and females.After receiving either AVP or placebo(PBO)intranasally in a randomized and double-blind manner,participants were asked to rate their approachability to facial expressions while electroencephalogram(EEG)were recorded.Males rated lower approachability scores to neutral and positive male faces relative to the scores to emotion-matched female faces after AVP but not following PBO administration,such behavioral effects corresponded with the AVP-induced increased P1 and decreased N170 amplitudes.Females rated higher approachability scores to negative female faces than the scores to negative male faces after AVP but not following PBO treatment.Moreover,the amplitudes of these ERP components can predict participant’s behavior outputs.These results suggest that AVP decreases friendly responses to neutral and positive same-gender faces in males but increases friendly responses to negative same-gender faces in femalesStudy 2 was to investigate the functions of AVP on human paternal behaviors,specifically how AVP affects male’s behavioral and neural responses to infant cues.In experiment 1,after randomized and double-blind treatment of AVP or PBO,participants were asked to rate their subjective approachability to infant and adult faces while EEG were recording.The results showed that AVP treatment sustained pronounced late positive potential amplitudes(LPP)to neutral infant but not adult cues.The finding suggested that AVP alters the neural responses toward neutral infant cues.The experiment 2 used a similar paradigm excepted that we modified experiment design and fMRI to localize the neural substrates underlying AVP effects.We found that AVP enhanced the approachability ratings and the activation of important regions in parental brain,including the areas of middle cingulate gyrus,thalamus and left fusiform,toward neutral infant faces,presumably due to the reason that these infant faces were presented in an emotionally-ambiguous way.In this regard,AVP administration rendered males to allocate more attentional resource to those ambiguous infant cues,thus the results of study 2 support the hypothesis that AVP facilitates paternal behavior in human malesOverall,study 1 confirmed that the effects of AVP on pair-bonding depends on gender Specifically,AVP enhanced perceived aggression toward male in males and promotes affinitive response toward female in females.Study 2 found that AVP can promote the processing and facilitate affinitive behaviors in response to infant cues in males.These findings provided empirical evidences that AVP plays an important role in human social bonding.