Neurons in the prefrontal cortex of the monkey brain keep track of the rewards animals hold on to and those they give away, reports a study published online this week in Nature Neuroscience. These findings suggest that this brain area may support altruistic behavior.

Areas in the front of the brain carry information about rewarding events. Michael Platt and colleagues show that one region in particular, the anterior cingulate gyrus, responds to whether one monkey gets a reward or gives it away to another. Monkeys performed a task where they were given a choice between receiving some juice or letting another monkey sitting next to them have it. While monkeys mostly like to drink the juice themselves, sometimes they would act unselfishly and give it away to the other monkey. Some brains cells responded only when the monkeys drank the juice, while other responded only when the juice was given away to the other monkey. However, some neurons responded no matter who received the juice, suggesting that these neurons keep track of the social value of rewards.