Figure 1. Hypothetical neural circuitry of agonistic behaviors of muroid rodents, showing location of
hormonal and learning effects. Hormonal effects shown are those of androgens (A), estrogens (E),
corticosteroids (C) and hormones of pregnancy and lactation (P). Learning effects, numbered 1-8, are
explained in the text. Three motivational systems are shown: offense, defense and patrol/marking. Four components are shown for each system: the motivational mechanisms, motor patterning mechanisms and two types of sensory analyzers and synthesizers - one set for motivating stimuli and one set for releasing and directing stimuli. Facilitative effects are illustrated by forks at tips of projections from one structure to another. Inhibitory effects are illustrated as filled circles. Projections that are present in some species but not in others are shown as dotted lines.