Humans often sacrifice material benefits to endorse or to oppose societal causes based on moral beliefs. Charitable donation behavior, which has been the target of recent experimental economics studies, is an outstanding contemporary manifestation of this ability. Yet the neural bases of this unique aspect of human altruism, which extends beyond interpersonal interactions, remain obscure. Moll et al. have used functional magnetic resonance imaging while participants anonymously donated to or opposed real charitable organizations related to major societal causes. They show that the mesolimbic reward system is engaged by donations in the same way as when monetary rewards are obtained.
Furthermore, medial orbitofrontal–subgenual and lateral orbitofrontal areas, which also play key roles in more primitive mechanisms of social attachment and aversion, specificalculy mediate decisions to donate or to oppose societal causes. More anterior sectors of the prefrontal cortex are distinctively recruited when altruistic choices prevail over selfish material interests.
Figure - Brain responses for monetary reward and donation. (a) Mesolimbic–striatal reward system, including the VTA and the dorsal and ventral sectors of the striatum (STR), activation for both pure monetary reward and noncostly donation (conjunction of pure reward vs. baseline and noncostly donation vs. baseline). (b) Subgenual area (SG) activation for decisions to donate (conjunction of costly and noncostly conditions) as compared with pure monetary reward.
Figure - Brain responses for opposition and costly decisions. (a) lOFC responses to decisions to oppose causes as compared with decisions involving pure monetary reward (conjunction of costly and noncostly conditions). (b) Comparison of costly decisions (sacrificing money either to donate or to oppose causes) to pure monetary rewards. Effects were observed in the anterior prefrontal cortex (aPFC), including the frontopolar cortex and the medial frontal gyrus (BA 10/11/32), and in the dorsal anterior cingulate cortex (dACC).