Unmasked: the elixir of human bonding

Hormone that makes mothers and babies bond also helps us to remember strangers' faces, study finds

Science Editor,Steve Connor
Wednesday 07 January 2009 01:00 GMT

It is said to be a love hormone that helps breastfeeding mothers to bond with their babies, as well as a "trust serum" secreted in the brain to inspire confidence in anyone from a lover to a business partner.

Now scientists have found the first experimental evidence to show that the hormone oxytocin plays an important role in helping us to remember the face of a stranger, a feat critical for maintaining the cohesion of society.

A study has found that men who sniffed a nasal spray containing oxytocin perform significantly better on a facial memory test where they have to recognise the faces of strangers a day after they had inhaled the hormone.

Scientists believe the findings provide strong support for the idea that oxytocin acts as a ubiquitous chemical glue within the brain to cement the personal relationships that are critical for the peaceful co-existence of individuals living within a social group.

The results will no doubt attract the attention of companies ranging from perfume manufacturers keen to develop the ultimate elixir of love, to marketing organisations hoping to spray department stores with trust-inducing scents to revive flagging consumers with feel-good factors. Oxytocin is secreted in the brain during lovemaking and is believed to play a key role in strengthening monogamous bonding of males and females, but until now no one has shown that it can improve the ability of the brain to remember faces.

The scientists found the inhalation of oxytocin only stimulated the part of the memory system tasked with recollecting faces, without affecting the system for remembering objects. "This is the first study to show oxytocin improves recognition for faces, but not for non-social stimuli," said Peter Klaver of the University of Zurich, who took part in the study published today in The Journal of Neuroscience. "Recognising a familiar face is a crucial feature of successful social interaction. In this study, we investigated the systematic effect of oxytocin on social memory in humans."

A group of 44 male volunteers were split in two, with each team asked either to sniff oxytocin, or a harmless nasal spray, three times in each nostril over a period of two minutes. A day later they were asked to identify faces they had seen briefly the day before.

Those given oxytocin correctly identified 46 per cent of faces, while those taking the placebo managed 36 per cent. The 10 per cent improvement was statistically significant, Dr Klaver said: "It shows that human memory for faces can be improved by oxytocin."

Oxytocin is a small molecule called a peptide. It is released by the pituitary gland at the base of the brain and is found within the brain and other selected sites of the body – such as the nipples of lactating women.

The latest findings support the idea that oxytocin is critical component of the system that stimulates the recognition, thereby the trust, of strangers. "Some suggest oxytocin could be used to improve trust in communities, but the mechanism of how it works may be too specific for this," Dr Klaver said.

Explainer: Oxytocin

Oxytocin is produced in the brain as well as being released by the pituitary gland at the base of the brain. It enters the bloodstream and affects other parts of the body, such as the nipples of lactating women, where it induces the release of milk. Many parts of the brain are affected by it, including the amygdala, which is involved in emotions such as fear and sexual behaviour. The hormone was isolated in 1953 and given to women to induce labour. It is released into the blood of both sexes during orgasm.

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