In a new study, researchers have discovered that we use a different part of our brain to learn about social hierarchies than we do to learn ordinary information.
People are remarkably good at ranking each other within social hierarchies, a survival technique that helps us avoid conflict and select advantageous allies, according to a team of researchers at the University College London Institute for Cognitive Neuroscience.
But we know very little about how the brain determines who is the top dog, which is why the researchers used brain imaging techniques to investigate this in 26 healthy volunteers.
The volunteers were asked to play a science fiction computer game where they would act as future investors. In the first phase, they were told they needed to learn which individuals have more power within a fictitious space mining company — the social hierarchy — and then which galaxies have more precious minerals, which is the non-social information.
While they were playing the game, the researchers used functional magnetic resonance imaging (fMRI) to monitor brain activity. Another MRI scan was taken to look at their brain structure.
The findings reveal a striking dissociation between the neural circuits used to learn social and non-social hierarchies, according to the researchers.
They report they observed increased neural activity in both the amygdala and the hippocampus when participants were learning about the hierarchy of executives within the fictitious space mining company.
In contrast, when learning the non-social information, relating to which galaxies had more minerals, only the hippocampus was recruited.
The researchers also found that those who were better at learning the social hierarchy had an increased volume of grey matter in the amygdala.
“These findings are telling us that the amygdala is specifically involved in learning information about social rank based on experience and suggest that separate neural circuits are involved than for learning hierarchy information of a non-social nature,” said Dr. Dharshan Kumaran, who led the study.
In a second phase of the experiment, researchers looked at how we recall information about social rank when we meet somebody again. They asked the volunteers to place bids on investment projects based on the knowledge about rank they had acquired during the first phase of the experiment. This was played out in the game as a particular executive heading up a mission to harvest minerals from a galaxy.
They found evidence that social rank is translated into neural activity in the amygdala in a linear fashion.
The level of activity in the amygdala was observed to increase according to the social rank of the person being encountered, the researchers explain. This increased activity provides a potential mechanism by which individuals select advantageous coalition partners in the real world based on their rank.
Being able to interpret social rank is important for us to meet the challenging pressures of living in large social groups, the researchers said, explaining that knowing where we fit into a social group determines how we behave towards different people.
As well as giving new understanding of which brain circuits are involved in learning and storing this information, the findings help explain why some people are better at it than others, according to the researchers.
The study was published in the journal Neuron.
Source: The Wellcome Trust