Steve Chang and his colleagues from Duke University in Durham, North Carolina, have discovered that monkeys have a specific area in their brains to keep track of altruistic acts. This might help researchers understand the mechanisms underlying normal social behavior in primates and humans, and could even provide insight about autism spectrum disorder.
The scientists published their findings in the journal Nature Neuroscience¹. They used electrodes to directly record neuronal activity in three areas of the prefrontal cortex, an area that is known to be involved in social decision-making while the monkey performed reward-related tasks.
When the monkeys had the choice to drink juice from a tube for themselves or give it to another, they would mostly drink it themselves. However, when the choice was between giving juice to a neighbor or neither monkey receiving anything, the monkey would often choose to give the juice to the other.
The researchers found that in two out of the three brain areas being recorded, neurons fired in the presence or absence of the juice reward only. By contrast, the area known as the anterior cingulate gyrus responded only when the monkey allocated the juice to the neighbor and observed it being received. The scientists suggest that the neurons in the ACG respond to and record the act simultaneously.
The ACG is known to be a region specialized for social decision-making in primates, and it is located in the same area of the brain as that associated with the generation of feelings of empathy in humans.
Whether the ACG operates in a similar fashion in humans hasn’t been demonstrated yet, but the authors suggest that the intricate balance between the signaling of neurons in these three brain regions may be crucial for normal social behavior in humans, and that disruption may contribute to various psychiatric conditions, including autistic spectrum disorders.
- Chang, S. W. C., Gariépy, J.-F. & Platt, M. L. Nature Neuroscience dx.doi.org/10.1038/nn.3287 (2012).