Neural Control Of Jealousy And Modulatory Effects Of Oxytocin

Romantic jealousy is a complex social emotion combining the primary emotions of anger,fear and sadness.Non-morbid jealousy can help stabilize relationships whereas in its more severe forms,pathological jealousy can be destructive to both individuals and society.Previous evidence has suggested the involvement of fronto-striatal dopaminergic circuitry in pathological jealousy,although little is known about the neural representation of non-morbid jealousy.It is therefore important to use a dimensional approach to help establish the main neural or chemical factors involved in the control of romantic jealousy in intimate relationships since this may have potential therapeutic value for pathological jealousy.Against this background the current dissertation described three studies investigating the neural control of jealousy,specifically focusing on the neural substrates of trait jealousy and the modulatory effects of the neuropeptide oxytocin(OXT).Study 1 employed a dimensional neuroimaging approach to investigate the neural substrates of trait jealousy while processing static emotional faces.The current study carried out functional magnetic resonance imaging(fMRI)in 85 healthy adults to determine neural activation and functional connectivity changes associated with trait jealousy both during resting state and a face emotion task.A total of 150 faces(happy,angry,fearful,sad,neutral)were presented and subjects required to identify the emotional expression and rate its intensity.fMRI results showed that during processing of static angry versus neutral expression faces,subjects with higher trait jealousy scores exhibited increased activation in the right thalamus,insula,fusiform gyrus and hippocampus,left dorsal striatum,superior parietal lobule and bilateral cerebellum and inferior frontal gyrus after controlling for trait aggression and sex.Functional connectivity between the inferior frontal gyrus and dorsal striatum was also increased.No associations with resting-state functional connectivity were found.These findings demonstrated the neural substrates associated with trait jealousy using a dimensional approach in healthy subjects and provide the first evidence that altered dopaminergic fronto-striatal circuitry may be a feature of non-morbid as well as pathological jealousy.In study 2 a large cohort of 237 male and female Chinese adult subjects were therefore exposed to 100 dynamic face emotion stimuli(happy,angry,fear,disgust,cheek blowing)and associations between neural responses and trait jealousy analyzed using trait aggression as a covariate.Results also demonstrated a significant positive correlation in male subjects between trait jealousy and activations of regions associated with both emotion and action processing and implicated in pathological jealousy,including bilateral superior frontal gyrus,bilateral inferior parietal lobe,left inferior frontal gyrus,left middle cingulate cortex,and right insula when processing dynamic angry expressions.Intriguingly,female subjects showed the opposite pattern of association with significant negative correlations between jealousy scores and neural activation.Furthermore,functional connectivity between the inferior frontal gyrus and middle cingulate cortex was decreased in males with higher jealousy traits but increased in females.This gender effect on neural responses associated with trait jealousy towards dynamic threatening emotions with higher ecological validity may reflect possible sex differences in approach/avoidance responses to dynamic as opposed to static stimuli.Additionally,no associations with resting-state functional connectivity were found.In study 3,we investigated the effects of oxytocin on romantic jealousy in intimate relationships.The effects of intranasal oxytocin(24 IU)were determined in a double-blind,placebo-controlled,between subject design behavioral study of 70 heterosexual couples,on levels of romantic jealousy evoked by both imagined and real contexts of partner infidelity.Experiment 1 determined the effects of oxytocin on jealousy evoked in the context of imagined infidelity by a partner and experiment 2jealousy evoked in a real situation where one partner interacted preferentially with a rival stranger of the opposite sex and excluded their current romantic partner while playing a modified ball-tossing game(Cyberball).Results of experiment 1 showed that oxytocin decreased jealousy ratings towards imagined emotional and sexual infidelity by a partner in both sexes.Results of experiment 2 demonstrated that during the Cyberball game,while male and female subjects in both groups subsequently threw the ball least often to the rival stranger,under oxytocin both sexes showed reduced romantic jealousy and arousal ratings for this stranger and reported reduced negative and increased positive feelings while playing the game.Together,our results provide the first evidence that the oxytocinergic system is involved in reducing the emotional impact of jealousy evoked by imagined or real infidelity in romantic partners.This provides further support for an important role of oxytocin in promoting the maintenance of relationships.In summary,the findings of the above studies have demonstrated that increased emotional responsivity to static social threat and activity in limbic regions and dopaminergic fronto-striatal circuitry may be features of both non-morbid and pathological jealousy.While responses to dynamic social threat stimuli are also associated with neural regions involved in jealousy,they exhibit sex differences in their direction.As predicted,jealousy associations could only be demonstrated in terms of altered responses to threat and not in resting-state intrinsic circuitry.Importantly,intranasal oxytocin can reduce jealousy in both sexes and in both real and imagined contexts.Thus,these new findings deepen our understanding of the neural representation and neurochemical modulation of jealousy.Furthermore,they also provide support for the potential therapeutic application of oxytocin in pathological jealousy disorder.