Over the past few years neural networks have been the subject of an explosion of interest from both the scientific research community and the popular media. However, the question of whether one needs to incorporate all the features that real neural networks have at either a neuronal or circuit level is the subject of much debate. Neural networks (both real and artificial) operate according to the same general principles: input from the outside world causes neurons to ‘fire’. The above is, to say the least, a very crude description of the basic processes of neural networks. The key point to realise about neural networks in relation to this debate is their extreme plasticity.