In Praise of Walking: A New Scientific Exploration

by Shane O'Mara

Using microelectrodes implanted in the human brain, we have learned that we have place cells too.12 They have come to be recognised as the core elements of the cognitive map – they tell you where you are in the world, and they work best, and acquire most information, when we are walking. Place cells can also sometimes code for which way the rat is pointing. In rats, place cells are often recorded on ‘radial mazes’ – an experimental set-up with a central hub, the rat’s task being to walk to the end of the corridors of the mazes and retrieve food pellets. Under these circumstances, place cells have directional preferences: they will fire in one direction but not in the other. Part of the problem when we are lost, whether hillwalking or while in an unfamiliar part of town, is that you are likely to have been walking in a single direction. Your place cells will fire when you are walking in one direction but not the other. And when you realise that you’re lost, it’s because you aren’t getting the constant feed that hippocampal place cells provide.