Meaningful social interactions are critical to a person’s wellbeing, and such interactions depend on how people behave towards one another.
In research published in Science, Massachusetts General Hospital (MGH) researchers mapped the neurons in the brain that enable one monkey to process and remember another monkey’s interactions and behaviors in order to influence the animal’s own actions . The results could be used to develop treatment strategies for people with neuropsychiatric disorders.
In the study, three rhesus monkeys sat around a turntable and took turns offering one of the other two monkeys an apple slice. At the same time, the researchers recorded the activity of individual neurons in an area of the brain known to play a role in social cognition, known as the dorsomedial prefrontal cortex (dmPFC).
During these interactions, the monkeys returned past offers of an apple slice and reciprocated if they did not receive a slice from another. The researchers’ recordings identified various neurons in the dmPFC that responded to the actions of other monkeys in the group.
Certain neurons were activated by certain individuals within the group with a certain action and a certain result (e.g. a neighboring monkey offering a piece of apple leads to the receipt of the reward). Many of the neurons encoded information not only about the actions and outcomes of certain people, but also about their previous behavior.
This information about past interactions with group members influenced an animal’s upcoming decisions to retaliate or take revenge, and researchers were able to use the neural information to predict which monkey would receive a piece of apple from a particular monkey before it was even offered.
This finding suggests that the dmPFC plays a role in strategic decisions. To test this idea, we stopped normal activity in this area and found that the animals were less likely to reciprocate. “
Raymundo Báez-Mendoza, PhD, Study Director and Investigator, Department of Neurosurgery, Massachusetts General Hospital
The results suggest that the dmPFC plays an important role in representing our actions and results, as well as the actions of others. “For neuropsychiatric conditions where this ability is impaired, treatments that directly or indirectly aim to improve the functioning of this area of the brain can improve people’s lives,” says senior author Ziv Williams, MD.
Massachusetts General Hospital
Báez-Mendoza-R., Et al. (2021) Identity cells of social agents in the prefrontal cortex of interacting groups of primates. Science. doi.org/10.1126/science.abb4149.