The brain histaminergic system, whose cell bodies are in the tuberomammillary nucleus, regulates various memory types. The best studied is inhibitory avoidance, which depends on histamine H2 receptors in hippocampus and basolateral amygdala, contextual fear conditioning, which depends on histamine H3 receptors in hippocampus, and the extinction of these two tasks, which relies on histamine H2 receptors in the ventromedial prefrontal cortex, hippocampus, and basolateral amygdala. In addition, histamine can promote fear extinction through H1 receptors and inhibit it through H2 receptors, both in hippocampus.