Decision to give a group effort in the brain

A monkey would probably never agree that it is better to give than to receive, but they do apparently get some reward from giving to another monkey.

During a task in which rhesus macaques had control over whether they or another monkey would receive a squirt of fruit juice, three distinct areas of the brain were found to be involved in weighing benefits to oneself against benefits to the other, according to new research by Duke University researchers.

The team used sensitive electrodes to detect the activity of individual neurons as the animals weighed different scenarios, such as whether to reward themselves, the other monkey or nobody at all. Three areas of the brain were seen to weigh the problem differently depending on the social context of the reward. The research appears Dec. 24 in the journal Nature Neuroscience.

Using a computer screen to allocate juice rewards, the monkeys preferred to reward themselves first and foremost. But they also chose to reward the other monkey when it was either that or nothing for either of them. They also were more likely to give the reward to a monkey they knew over one they didn’t, preferred to give to lower status than higher status monkeys, and had almost no interest in giving the juice to an inanimate object.

Calculating the social aspects of the reward system seems to be a combination of action by two centers involved in calculating all sorts of rewards and a third center that adds the social dimension, according to lead researcher Michael Platt, director of the Duke Institute for Brain Sciences and the Center for Cognitive Neuroscience.

The orbital frontal cortex, right above the eyes, was activated when calculating rewards to the self. The anterior cingulate sulcus in the middle of the top of the brain seemed to calculate giving up a reward. But both centers appear “divorced from social context,” Platt said. A third area, the anterior cingulate gyrus (ACCg), seemed to “care a lot about what happened to the other monkey,” Platt said.

Based on results of various combinations of the reward-giving scenario the monkeys were put through, it would appear that neurons in the ACCg encode both the giving and receiving of rewards, and do so in a remarkably similar way.

The use of single-neuron electrodes to measure the activity of brain areas gives a much more precise picture than brain imaging, Platt said. Even the best imaging available now is “a six-second snapshot of tens of thousands of neurons,” which are typically operating in milliseconds.

What the team has seen happening is consistent with other studies of damaged ACCg regions in which animals lost their typical hesitation about retrieving food when facing social choices. This same region of the brain is active in people when they empathize with someone else.

"Many neurons in the anterior cingulate gyrus (ACCg) respond both when monkeys choose a drink for themselves and when they choose to give a drink to another monkey," Platt said. "One might view these as sort of mirror neurons for the reward system." The region is active as an animal merely watches another animal receiving a reward without having one themselves.

The research is another piece of the puzzle as neuroscientists search for the roots of charity and social behavior in our species and others. There have been two schools of thought about how the social reward system is set up, Platt said. One holds that there is generic circuitry for rewards that has been adapted to our social behavior because it helped humans and other social animals like monkeys thrive. Another school holds that social behavior is so important to humans and other highly social animals like monkeys that there may be some special circuits for it, Platt said.

This finding, in macaques that have only a very distant common ancestor with us and are “not a particularly prosocial animal,” suggests that “this specialized social circuitry evolved a long time ago presumably to support cooperative behavior,” Platt said.

(Photo: EPA)

How Random Is Social Behaviour? Disentangling Social Complexity through the Study of a Wild House Mouse Population

Out of all the complex phenomena displayed in the behaviour of animal groups, many are thought to be emergent properties of rather simple decisions at the individual level. Some of these phenomena may also be explained by random processes only. Here we investigate to what extent the interaction dynamics of a population of wild house mice (Mus domesticus) in their natural environment can be explained by a simple stochastic model. We first introduce the notion of perceptual landscape, a novel tool used here to describe the utilisation of space by the mouse colony based on the sampling of individuals in discrete locations. We then implement the behavioural assumptions of the perceptual landscape in a multi-agent simulation to verify their accuracy in the reproduction of observed social patterns. We find that many high-level features – with the exception of territoriality – of our behavioural dataset can be accounted for at the population level through the use of this simplified representation. Our findings underline the potential importance of random factors in the apparent complexity of the mice’s social structure. These results resonate in the general context of adaptive behaviour versus elementary environmental interactions.

If two birds meet deep in the forest, does anybody hear? Until now, nobody did, unless an intrepid biologist was hiding underneath a bush and watching their behavior, or the birds happened to meet near a research monitoring station. But an electronic tag designed at the University of Washington can for the first time see when birds meet in the wild.

A new study led by a biologist at Scotland’s University of St. Andrews used the UW tags to see whether crows might learn to use tools from one another. The findings, published in Current Biology, supported the theory by showing an unexpected amount of social mobility, with the crows often spending time near birds outside their immediate family.

The study looked at crows in New Caledonia, an archipelago of islands in the South Pacific. The crows are famous for using different tools to extract prey from deadwood and vegetation. Biologists wondered whether the birds might learn by watching each other.

The results, as reported by St. Andrews, revealed “a surprising number of contacts” between non-related crows. During one week, the technology recorded more than 28,000 interactions among 34 crows. While core family units of New Caledonian crows contain only three members, the study found all the birds were connected to the larger social network.

The new paper is the first published study using the UW tags to record animal social interactions.

Testosterone increases honesty

Researchers from the University of Bonn examine the biological background of lying

Testosterone is considered THE male hormone, standing for aggression and posturing. Researchers around Prof. Dr. Armin Falk, an economist from the University of Bonn, have now been able to demonstrate that this sex hormone surprisingly also fosters social behavior. In play situations, subjects who had received testosterone clearly lied less frequently than individuals who had only received a placebo. The results have just been published in the Public Library of Science’s international online journal “PLoS ONE.”

The hormone testosterone stands for typically male attributes – it fosters the forming of the sexual characteristics, increases libido and muscle building. Women also have this sex hormone, but to a much lesser extent. “Testosterone has always been said to promote aggressive and risky behavior and posturing,” reports Prof. Dr. Bernd Weber, a neuro-scientist from the Center for Economics and Neuroscience (CENS) at the University of Bonn. More recent studies indicate, however, that this sex hormone also fosters social behavior.

(Photo: Getty Images)

Kids who get migraine headaches are much more likely than other children to also have behavioral difficulties, including social and attention issues, and anxiety and depression. The more frequent the headaches, the greater the effect, according to research out now in the journal Cephalagia, published by SAGE.

Marco Arruda, director of the Glia Institute in São Paulo, Brazil, together with Marcelo Bigal of the Albert Einstein College of Medicine in New York studied 1,856 Brazilian children aged 5 to 11. The authors say that this is the first large, community based study of its kind to look at how children’s behavioural and emotional symptoms correlate with migraine and tension-type headaches (TTH), and to incorporate data on headache frequency.