Working out who’s top dog

A new study reveals how the brain interprets information about social hierarchy. Dr Jen Middleton, senior media officer at the Wellcome Trust, explains the findings and what they might mean in real life.

As a child, my father’s job meant a lot of moving around to exotic places: Brazil, South Korea, Australia. While this experience was filled with great adventure and excitement, I always felt a brief stab of anxiety at knowing that, yet again, I’d be starting a new school. It meant making new friends, and making new friends meant making sense of the sea of faces and working out where I might fit into the social melee.

Primates (including people) are remarkably good at ranking each other within social hierarchies, a survival technique that helps us to avoid conflict and select advantageous allies, something that is extremely important in the playground. However, we know surprisingly little about how the brain does this. Using brain imaging techniques, researchers supported by the Wellcome Trust have now shown that we use a different part of our brain to learn about social hierarchies than we do to learn ordinary information. Not only that but you can actually tell a lot about how good somebody is likely to be at learning social rank by looking at the structure of their brain.

In a study published today in the journal Neuron, the team describes how the amygdala and the hippocampus are involved in learning information about social rank whereas only the hippocampus is involved in learning non-social information. They also found that participants who were better at learning a social hierarchy had an increased volume of grey matter in the amygdala compared to those less able.

When it comes to recalling information about rank, they showed that neural activity in the amygdala increased on a linear scale according to the level of rank of the person encountered. This, they suggest, could offer a mechanism by which an individual might choose advantageous allies in the real world, based on social rank.

That the amygdala is important for interpreting social information is nothing new. Previous studies have shown that teenagers with severe behavioural problems have less brain activity in the amygdala, which could underlie their insensitivity to the distress of others and to social signals of aggression. What is interesting in this new study is that it shows that there are different neural circuits involved in learning social information compared with ordinary information – and it reveals how this social knowledge may actually be represented in the brain.

The researchers are now keen to look at people with brain and developmental disorders to see how their ability to learn social hierarchies is affected. I’d be interested to know whether we can get better at learning and using social hierarchies with experience and, if so, whether I’ve got a stonking great volume of grey matter in my amygdala grown from years of moving schools .

Reference:

D. Kumaran, H.L Melo & E. Duzel. The emergence and representation of knowledge about social and non-social hierarchies. Neuron 76 (3) 653, 2012.

Image credit: Wellcome Library, London (Wellcome Images)