Fig. 6.
Models of courtship conditioning. Previous and current models of courtship conditioning are depicted. In the network model, a positive pathway responsive to both visual input and stimulatory pheromone and a negative pathway responsive to aversive pheromone are connected to the output center controlling male courtship. —‖ indicates an excitatory connection; —• indicates an inhibitory connection. Gray shading indicates connections at which CaM kinase-dependent heterosynaptic plasticity is expressed in the positive and negative pathways. Rules for synaptic strength modulation are as follows: (1) concurrent activity in the negative pathway and the courtship motor center leads to strengthening of the connection between the negative pathway and the motor center, and (2) concurrent activity in the positive pathway and the negative pathway leads to weakening of the connection between the positive pathway and the motor center.