In patients with a psychiatric condition known as borderline personality disorder, a single dose of oxytocin has been found to hinder trust and cooperation
Neuroscience: The hard science of oxytocin
As researchers work out how oxytocin affects the brain, the hormone is shedding its reputation as a simple cuddle chemical.
In April 2011, Robert Froemke and his team were reprogramming the brains of virgin mice with a single hormone injection.
Before the treatment, the female mice were largely indifferent to the cries of a distressed baby, and were even known to trample over them. But after an injection of oxytocin, the mice started to respond more like mothers, picking up the mewling pup in their mouths. Froemke, a neuroscientist at New York University’s Langone Medical Center in New York City, was monitoring the animals’ brains to find out why that happened.
At first, the mice showed an irregular smattering of neural impulses when they heard the baby’s cries. Then, as the oxytocin kicked in, the signal evolved into a more orderly pattern typical of a maternal brain. The study showed in unusual detail how the hormone changed the behaviour of neurons. “Oxytocin is helping to transform the brain, to make it respond to those pup calls,” Froemke says.
Oxytocin has been of keen interest to neuroscientists since the 1970s, when studies started to show that it could drive maternal behaviour and social attachment in various species. Its involvement in a range of social behaviours, including monogamy in voles, mother–infant bonding in sheep, and even trust between humans, has earned it a reputation as the ‘hug hormone’. “People just concluded it was a bonding molecule, a cuddling hormone, and that’s the pervasive view in the popular press,” says Larry Young, a neuroscientist at Emory University in Atlanta, Georgia, who has been studying the molecule since the 1990s.