Why does it feel good to give — even at a cost to oneself, and even anonymously? In a new study, Jorge Moll and colleagues have used functional neuroimaging to investigate the neural source of the 'joy of giving'. They find that charitable donations activate the same neural systems as those that respond to monetary reward.

In the study, subjects were scanned using functional MRI while they made decisions about whether to donate to a charity (either with a cost to themselves or with no cost to themselves), to oppose the charity (again, with or without personal cost) or to receive a monetary reward. The charities were all associated with societal causes such as abortion, children's rights and euthanasia. The participants were also asked about their feelings towards the causes (compassion or anger) and about their real-life charitable donations.

A monetary reward caused activity in the mesolimbic reward system, including the ventral tegmental area and the striatum. Intriguingly, a decision to donate to charity led to even greater activity in this network. It also activated the subgenual area, which was not activated by monetary reward, and which has been implicated in social attachment. Costly donation and costly opposition — as compared with non-costly decisions — were also associated with activity in the anterior prefrontal cortex. The level of activity here correlated with participants' real-life charitable engagement, supporting the theory that the anterior prefrontal cortex is a key area in altruistic behaviour.

The decision to oppose a cause, whether at a cost or at no cost, was also associated with activity in the lateral orbitofrontal cortex. This region has previously been implicated in aversive responses such as anger and moral disgust, consistent with the subjects' reported feelings about causes they chose to oppose.

These results shed light on the link between altruistic behaviour and reward systems in the brain, and on the role of the anterior prefrontal cortex in resolving conflicts between motivation related to personal gain and moral altruism.