The limbic system is associated with primitive emotions and higher mental functions. It is a complex network of tracts and nuclei that incorporates portions of the cerebral lobes (cerebrum), the basal nuclei, and the (Click to select) . The amygdala and the (Click to select) are two significant structures within the limbic system essential for learning and memory. The (Click to select) is an almond-shaped structure involved in responses to and displays of anger, avoidance, defensiveness, and fear, and prompts release of (Click to select) and other hormones into the bloodstream. The hippocampus is a seahorse-shaped structure deep in the (Click to select) lobe; it is physiologically structured to communicate effectively with the prefrontal area of the brain, which is also involved in learning and memory.