Part (a) shows a schematic neural network with intact connections between the constituent neurons. In part (b) some of the neurons are shown damaged and so fail to make their connection with a neighbouring neuron. Part (c) shows part of a damaged network on the left and part of an intact network on the right, and between them is a list of four antidepressant treatments that can enhance the plasticity processes needed to remake the neuronal connections and so repair the damaged.