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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Biology of romantic love | 8/14 | https://en.wikipedia.org/wiki/Biology_of_romantic_love | reference | science, encyclopedia | 2026-05-05T15:53:39.742070+00:00 | kb-cron |
=== Oxytocin, bonding, and attraction ===
Oxytocin is sometimes called the "love hormone", because of its involvement in the mechanisms of maternal behavior and adult pair bonding. Oxytocin is synthesized primarily in an area of the hypothalamus and released into the blood via the pituitary gland, where it has been found circulating in people in the early stages of romantic love. Additionally, the hypothalamus projects oxytocin to other areas of the brain, like the ventral tegmental area (VTA), nucleus accumbens (NAc), amygdala, and hippocampus. The projections to reward areas (VTA and NAc) are thought to modulate social salience, or i.e. the level of dopamine activity in response to socially-relevant stimuli. This oxytocin signaling in reward pathways may also be the source of salience in response to a loved one. A placebo-controlled study found that administering intranasal oxytocin enhanced facial attractiveness of a romantic partner while viewing a photograph, as compared to an unfamiliar face. The effect was also measured using fMRI, which found enhanced brain activity in reward areas like the VTA and NAc. Another fMRI study found dopamine-rich genetic expression of an oxytocin receptor gene in the left VTA, and the left VTA has also been found active in response to facial attractiveness. In humans, circulating oxytocin levels have been associated with higher levels of interaction between partners, and also predicted which couples would still be together 6 months later. Anna Machin calls the combination of oxytocin and dopamine the "glue" which makes the early stages of a relationship possible. The role of oxytocin in human behavior is varied and complex. Oxytocin lowers inhibitions to forming new relationships by deactivating the amygdala, involved with processing fear and anxiety. Oxytocin can be released with physical touch, hence it's also sometimes called the "cuddle hormone". Oxytocin also plays a role in sexual behavior, being released during sexual arousal and orgasm. Aside from romantic and parental bonding, oxytocin activity has a role in the interactions with peers or strangers, for example facilitating facial recognition and eye contact. Oxytocin is believed to facilitate trust and altruistic behaviors towards in-groups (e.g. partners or children), but also aggression towards out-groups (e.g. strangers or conspecifics). Much of the research on oxytocin comes from experiments on monogamous prairie voles (notably by Larry Young), but this research is also used for making inferences about humans. In prairie voles, both oxytocin and dopamine signaling have been shown to influence pair bond development. For example, the number of oxytocin receptors in the NAc is positively related to how fast a partner preference is formed. A partner preference can also be prevented by injecting either a dopamine or oxytocin receptor antagonist (a drug which blocks transmission) into the NAc of a prairie vole directly. In a contemporary model of the brain systems involved with romantic love, this type of salience (or 'bonding attraction') is present throughout the entire time a person is experiencing romantic love, including during the early stages. This contrasts with some previous theories (e.g. proposed by Helen Fisher in 1998) which stated that oxytocin activity and dopamine activity were distinct (and independent) systems, and that oxytocin activity only became prominent at some later stage of a relationship. Levels of oxytocin would still vary from situation to situation because of differing types of stimuli, for example because of less regular interaction and physical touch in cases of unrequited love. This could be used to explain some of the maladaptive symptoms of infatuation (e.g. sleep difficulties, social anxiety, clammy hands, etc.), when dopaminergic activity is high without the calming effect of oxytocin from the attachment system.
=== Brain opioid theory of social attachment ===