Kolb – play and brain development

So when we let the animals engage in play we can then look in their brains as adults and say what happened? And what we find happens is that the cells in the frontal lobe are profoundly altered, so the cells in this region in the rat brain which would be equivalent to probably this region in our brain, change their connectivity. They actually reduce the number of connections.  

So we can control, we can manipulate two things: the number of animals you live with, and the amount of play you engage in. We can do that by having you live when you’re weaned with one adult or several adults, or we can live with one littermate or several littermates. The more littermates you live with, the more play you engage in, the more adults you live with the more interaction there is with the other adults but there’s virtually no play behaviour. If we then look in adulthood at the frontal lobe of these animals what we find is that both experiences alter the way the frontal lobe developed. It’s counter intuitive in what happens because if you look at frontal lobe development in rodents or in humans what happens in you have this rapid increase in the number of connections which peaks in the frontal lobe of humans around five years, between two and five years and then shows this decline that’s rather rapid through the pre-adolescent and adolescent period but actually continues until about at least age 30 years. In the rodent it’s compacted, but it’s the same logic, that is you have this increase and drop and during the adolescent period a rapid drop and then a leveling off into adulthood. 

So what we find is a reduction in the number of synapses in this region related to the amount of play. The more play you engage in, the fewer the connections are, and you might think well that’s a bad thing, you have fewer connections, but it’s not. The number of connections whether it’s bigger or smaller doesn’t predict very much 

So now what we’ve got is the frontal lobe, which is the brain’s executive be influence profoundly by this early play experience. So what? Well, there’s two ways to go here. One is to say, alright, if play’s important for adult behaviour, what kinds of things during development will interfere with play? Peri-natal stress changes play; animals play less and the other animals don’t really want to play with them. Peri-natal exposure, and then juvenile exposure to drugs such as methyphenoate, so stimulants in general actually reduce the amount of play and actually the play behaviour the animals engage in isn’t normal, they don’t follow the rules and so other animals don’t want to play with them. Autism, you can fill in the blanks. All sorts of early experiences alter play. What’s that mean? If you alter play, you’re altering brain development. The frontal lobe isn’t developing the way it ought to develop because of that change in play.