6 January 2012
Monkeys feel the love on oxytocin
by Will Parker
Duke University researchers evaluating the effectiveness of oxytocin - the "love" hormone - in treating autism and schizophrenia say that their experiments with monkeys indicate that oxytocin enhances social interaction and increases trust.
Duke neuroscientist Michael Platt says that administering the hormone through a nebulizer can make rhesus macaques pay more attention to each other and make altruistic choices that give another monkey a squirt of fruit juice, even when they don't get one themselves.
In the experiment, two macaques were trained to select symbols from a screen that represented giving a rewarding squirt of juice to one's self, giving juice to the neighbor, or not handing out any juice at all. In repeated trials, they were faced with a choice between just two of these options at a time: reward to self vs. no reward; reward to self vs. reward to other; and reward to other vs. no reward.
"The inhaled oxytocin enhanced 'prosocial' choices by the monkeys, perhaps by making them pay more attention to the other individual," said Platt, who headed the study. "If that's true, it's really cool, because it suggests that oxytocin breaks down normal social barriers."
Earlier research by Platt's group had shown that macaques would rather give a reward to another monkey when the alternative is no reward for anyone, a concept they call "vicarious reinforcement." Their data in this study show an apparent improvement in vicarious reinforcement about a half-hour after exposure to oxytocin. Interestingly, for the first half-hour, the monkey was more likely to reward itself.
Platt says the study helps establish monkeys as a good behavioral and pharmacological model for understanding oxytocin therapy. "We were able to make the inhalation very tolerable by using the pediatric nebulizer," Platt said. "This may be much better for treating young children with autism or related disorders than the typical nasal spray, which can be uncomfortable."
Source: Duke University