Oxytocin alters the human reward system to maintain romantic love

Only 3 – 5% of mammalian species exhibit monogamy, raising the key question of what biological mechanism results in their attachment to one mate? The evolutionarily conserved hypothalamic peptide oxytocin (OXT) has been implicated in mediating pair-bonds in various species, although its potential involvement in maintaining monogamous bonds in humans has yet to be established. In a counter-balanced, double-blind, within-subject experiment we tested if OXT can bias men's perception of attractiveness of their female partner and alter the neural signature of romantic love. We used functional magnetic resonance imaging to scan 20 heterosexual pair-bonded men while they viewed pictures of their female partner, or other women, after intranasal administration of OXT (24 IU) or placebo. OXT selectively increased both attractiveness ratings for pictures of the female partner and activity in brain dopaminergic reward regions, including the ventral tegmental area (VTA) and nucleus accumbens (NAcc). In addition, OXT enhanced functional coupling between the VTA and dorso-striatal (caudate nucleus) and meso-limbic (NAcc) projection areas. Taken together, our results provide the first evidence that OXT may strengthen and maintain established monogamous bonds in men by selectively facilitating the attractiveness of visual cues from their female partners via increased activation of brain reward systems. This study was supported by R.H. was supported by a German Research Foundation (DFG) grant (HU1302/2 – 2) and by a Starting Independent Researcher Grant ('NEMO – Neuromodulation of Emotion') jointly provided by the Ministry of Innovation, Science, Research & Technology of the German State of North Rhine-Westphalia (MIWFT) and the University of Bonn.