Figure 5.

A GRN model of associative learning. A GRN model adapted from [141]. The dynamics of w1, w2 and p follow the ‘Hill’ function, which is traditionally used to model gene activation and repression behaviour through a binding process. An application of conditioned stimulus (CS) alone initially does not evoke a response (concentration of p is close to zero). However, an application of CS following a joint application of US–CS stimuli manages to evoke a response. This is because CS is ‘associated’ with US (unconditioned stimulus) during the joint application, in the sense that the GRN learns to ‘think’ that CS is equivalent to US during subsequent applications of CS alone. (Online version in colour.)