Common And Separable Brain Basis Of Romantic Love And Friendship Between The Sexes

Both love and heterosexual friendships are close social relationships that can be observed in every culture.Both relationships have been addressed by a wide range of scholars from different perspectives.Studies have shown that romantic love is associated with the maintenance of marital relationships,subjective well-being,life satisfaction,and mental health.Close friendships also have positive impact on mental health and wellbeing.Neuroimaging studies of romantic love as well as heterosexual friendship have identified an important contribution of the reward circuits,including the ventral striatum.However,common and different brain circuits remain debated.Therefore the aim of this study was to investigate the shared and separate neural basis of romantic love and heterosexual friendship.This study combined structural and functional magnetic resonance imaging techniques using activation level analysis,psychophysiological interaction analysis and voxel-based morphological analysis in 52 healthy university students currently in a romantic relationship.A memory recall task was used with functional MRI study,containing three experimental conditions: romantic memories with the partner,happy memories with a friend,and recall of a neutral event experienced by one self.Activation analyses revealed that both romantic love and heterosexual friendship memories enhanced activation in the ventral striatum,dorsomedial prefrontal,and posterior cingulate regions,and reduced activation in the right orbitofrontal cortex,ventral lateral prefrontal cortex,and limbic and parietal regions,compared to neutral stimuli.Romantic friendship,relative to heterosexual friendship and neutral conditions,showed enhanced activity in the dorsal anterior cingulate gyrus and precuneus bilaterally,and reduced activity in the orbitofrontal cortex,the dorsolateral prefrontal cortex,and the right angular gyrus and inferior parietal gyrus.Functional connectivity of the precuneus with the ventral striatum was enhanced in analyses of physiopsychological interactions with the ventral striatum as the seed point in the romantic love versus heterosexual friendship condition and the neutral versus heterosexual friendship condition.Voxel-based morphological analyses revealed a negative correlation between Passionate Love Scale scores and grey matter volume in the left orbitofrontal cortex,and a positive correlation between Friendship Quality Questionnaire scores and grey matter volume in the right precentral gyrus.In summary,ventral striatal regions were significantly associated with romantic love and heterosexual friendship;relative to heterosexual friendship and neutral conditions,romantic love was specifically associated with activity in several brain regions,including suppressed activity in frontal brain regions and enhanced activation in precuneus and cingulate brain regions.Neural representations of shared and separate romantic love and heterosexual friendship were confirmed.