Psychology of Sexual Monogamy - Attachment - Neural Processes of Attachment

Neural Processes of Attachment

Studies of pair bonding in animals have allowed scientists to identify several chemicals in the brain related to social monogamy. Three chemicals which have received a lot of attention are oxytocin, vasopressin, and dopamine. These chemicals have been strongly linked to socially monogamous pair bonding in prairie voles.

Some species of prairie voles form socially monogamous pair bonds following sexual behavior. The pair bonds can be interrupted by injecting chemicals that interfere with oxytocin and vasopressin. The chemicals do not interfere with sexual behavior. The chemicals interfere with the normal activity of oxytocin and vasopressin and thereby prevent the formation of pair bonds. Conversely, injecting chemicals that increase the activity of oxytocin and vasopressin causes social but not necessarily sexual monogamous pair bonds to form more easily. Increasing the activity of oxytocin and vasopressin can lead to pair bonding without the need for sexual behavior. Studies have also compared species of prairie voles that form socially monogamous pair bonds versus species of prairie voles that do not form socially monogamous pair bonds. The brains of species that form socially monogamous pair bonds contain more neurons that are more sensitive to oxytocin and vasopressin. (This is because the neurons contain more receptors, or chemical "docking ports," for oxytocin and vasopressin.) The findings of many studies have consistently shown that oxytocin and vasopressin play a critical role in socially monogamous pair bonding in prairie voles. For a better understanding of the findings here is an explanation from the director of the National Institute of Mental Health "Thomas Insel, director of the National Institute of Mental Health (formerly director of Yerkes Primate Center) and an expert on the prairie vole, says that those in the know have a less exalted view of the prairie vole's monogamy: "They'll sleep with anyone but they'll only sit by their partners." Biologist do not define monogamy the same way as most people. "The average person probably thinks of monogamy as a sexually exclusive relationship. Biologists, however, define the word a little differently. The monogamous animal is one that spends most of its time with one mate but is not entirely faithful, points out Insel. Most monogamous animals will, on occasion, mate with a stranger, he says. In addition, the monogamous male vole often takes a fiercely protective stance when a stranger threatens the nest. Finally, such males often help their mates with child-rearing tasks.""

Part of the effects of oxytocin and vasopressin may be due to their influence on dopamine in the reward circuits of the brain.

Reward circuits are neurons in the brain responsible for feelings of pleasure and reinforcement in response to positive stimuli such as food, sex, and social interaction. Dopamine is one of the key chemicals that controls the reward circuits of the brain. Oxytocin and vasopressin may influence how dopamine acts on the reward circuits. Thus, oxytocin and vasopressin may facilitate attachment to relationship partners by influencing the activity of dopamine in reward circuits during positive interactions with those partners.

Although human brains contain oxytocin, vasopressin, and dopamine, human brains differ in many respects from animal brains. These differences may include changes in how oxytocin, vasopressin, and dopamine work. Neuroscientists simply do not understand the differences between human brains and animal brains well enough to say these chemicals play a role in human pair bonding. Yet, initial studies look promising. Oxytocin reduces stress in human beings.

Oxytocin may facilitate attachment by reducing stress in response to the support and comfort offered by relationship partners. Oxytocin also increases trust in human beings.

Oxytocin may facilitate attachment by increasing trust between relationship partners. Brain scans have shown that areas of the human brain containing oxytocin, vasopressin, and dopamine are activated by looking at pictures of attachment figures but not by looking at pictures of other people.

The coming decades promise a better understanding of how oxytocin, vasopressin, and dopamine function in human attachment.

Recent studies have looked at which areas of the human brain play a role in attachment.

These studies asked people to look at pictures of their romantic partners or pictures of their children. Some areas of the brain were activated by both pictures of romantic partners and pictures of children. These areas of the brain were involved in both romantic and parental attachment. But other areas of the brain were activated only by pictures of romantic partners or only by pictures of children. These areas of the brain appeared to be involved in either romantic attachment or parental attachment, but not both. These findings have opened the door to future studies clarifying how different areas of the brain function in attachment.