As the season for giving sets in, even monkey brains respond to the act of giving finds researchers.
During a task involving rhesus macaques, three distinct areas of the brain were found to be involved in weighing benefits to oneself against benefits to the other, according to Duke University researchers.
The team used sensitive electrodes to detect the activity of individual neurons (nerve cells) as the animals weighed different scenarios, whether to reward themselves, the other monkey or nobody at all, the journal Nature Neuroscience reports.
Calculating the social aspects of the reward system seems to be a combination of action by two centres involved in calculating all sorts of rewards and a third centre that adds the social dimension, says Michael Platt, director of the Duke Institute for Brain Sciences who led the study, according to a Duke statement.
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, and preferred to give to lower status than higher status monkeys, and had almost no interest in giving the juice to an inanimate object.