Anatomically, the limbic system is a diverse group of structures located in an arc between the thalamus and the cerebrum. These structures work together to produce our most basic and primitive emotions, drives, and behaviors, including fear, rage, tranquility, hunger, thirst, pleasure, and sexual responses. The limbic system includes the hypothalamus, portions of the thalamus, the amygdala, and the hippocampus.

The hypothalamus contains many different clusters of neurons. Some of these are neurosecretory cells that release hormones. Through its hormone production and neural connections, the hypothalamus acts as a major coordinating center, controlling body temperature, hunger, the menstrual cycle, water balance, and the autonomic nervous system. In addition, stimulation of specific areas of the hypothalamus elicits emotions such as rage, fear, pleasure, and sexual arousal.

The amygdala is believed to be responsible for the production of appropriate behavioral responses to environmental stimuli. It receives input from many sources, including the auditory and visual areas of the cerebral cortex. Different clusters of neurons in the amygdala produce sensations of pleasure, punishment, or sexual arousal when stimulated. By stimulating different portions of the amygdala, researchers can either reduce or enhance aggressive behavior. Conscious humans whose amygdalas are electrically stimulated have reported feelings of rage or fear. Recent studies have revealed that damage to the human amygdala eliminates the person's ability both to feel fear and happiness.

The shape of the hippocampus as it curves around the thalamus inspired its name, which is derived from the Greek word meaning "sea horse". As in the amygdala and hypothalamus, behaviors that reflect a variety of emotions including rage and sexual arousal can be elicited by stimulating portions of the hippocampus. The hippocampus also plays an important role in the formation of long-term memory and is thus required for learning.