Monday, November 25, 2013

Linking social behavior to the brain

Tomorrow I am going to Stockholm to visit Niclas Kolm's new lab in Stockholm and start thinking about our project 'Linking social behavior to the brain'. We have received a rather large amount of money from the Wallenberg foundation to do this research (a popular science description in Swedish can be found here). My research group has recently published a rather nice series of papers on quantifying social interactions in fish and other animals, while Niclas' group has done some groundbreaking research on artificial selection in guppies. Combining these two ideas, going from social behavior to the brain, was an attractive combination. Adding to this some new perspectives in machine learning from Kristiaan Pelckmans and genomics from Judith Mank we have our very own social brain research dream team.

Section of the brain of a guppy artificially
selected for increased brain size
(photo by Laura Vossen).
O.K. I'll give the self-promotion a rest for now. We already got the research grant, so I don't need to go on about it! But I thought I'd write a little bit about what we are going to do. If society trusts us with a research grant, we should be able to explain what we are going to use the money for.

The starting point for our project is the social brain hypothesis: that humans and other primates have big brains because they have complex social lives. It takes a lot of brain power to keep track of all our friends and enemies. Just think about how much of your thoughts during today were dedicated to sorting out interpersonal relationships. You soon realize that you may well possess a social brain. And that brain costs you, not only through the time spent worrying about what other people think about you, but also because of the large amount of energy it consumes.

Our research will look at fish and their brains. Of course, fish do not have as complex brains as we do, but there is good reason to believe that the structure and capacity of the brain will effect social behavior, and visa-versa. Are fish bred for big brains more social than those with small brains? Are fish that are bred on the basis of their social interactions more likely to have smaller or larger brains? These are some of the things we aim to find out.

Turning response of a guppy as a function
of the position of its nearest neighbor
(image by Andrea Perna) 
It is important in this type of research to think clearly about what we mean by social interactions.  Interpersonal relationships are very different from many of the interactions seen in fish, where they follow each other and organize in to shoals. It is this latter type of interactions that we have been working on most recently (as in the image to the left). But guppies, the fish we will work on, have both the complicated interpersonal interactions where they 'recognize' each other and the simple behavioral interactions that determine their movements. We expect both of these to be important and will examine them in different ways.

Recent debate about the interpretation of Niclas and his co-workers results make my distinction between simple and complicated sociality all the more important. Sue Healy and Candy Rowe argued that differences in the ability of big and small brained fish to learn in a numerical task could be explained by changes in the motivation and stimulation of fish, instead of genuine intelligence differences. The suggestion is that simple behavioral rules can explain apparently complex outcomes. Naturally, Niclas is not convinced by their argument and their team gave a robust response. Our approach should allow us to get to the bottom of exactly these types of details. It will hopefully reveal some of the subtleties of the social brain.

This is a big project, and guppy breeding experiments are just part of it. We will develop better data analysis methods, make more accurate models of fish interactions, and look at in-silico evolution of fish shoaling (hence my recent revived interest in artificial life).  The project starts properly in July 2014, once Niclas has totally renovated his lab. We will be recruiting both theoretical and experimental Postdocs in the spring and there should be a possible PhD project too. Watch this space for more details.


  1. I'm curious what's known about fish now - do they have a PFC/is it enlarged in social fish compared to loners, etc?

  2. Just now, not very much. What Kolm and colleagues early work shows is that there are behavioral differences in fish selected for brain size. We would like to go the other way round. But establishing brain differences in social and non-social fish requires us first to have a good distinction of this, before we associate the social differences with brain differences. These social differences what we are working on first.