The Papez circuit is a pathway of the limbic system of the brain. It helps the cerebral cortex control emotions. This circuit also aids in memory retention.

James Papez, a neuroanatomist, provided the first description of the Papez circuit in 1937 after studying the effects of rabies introduced to the hippocampus of a cat. Papez noted the circuit was made up of several smaller areas of the cerebral cortex. This circuit carries information through the cortex as it processes emotions and memories and works to store them for easy recalling ability.

Information is sent throughout the Papez circuit to sections in the brain starting at the hippocampal formation, which contains the fornix and other parts, then to the mammillary bodies. From there, information travels to the mammillothalamic tract and on to the anterior thalamic nucleus. The internal capsule to the cingulate gyrus is next along the path.

After the cingulate gyrus, information continues to the cingulum and parahippocampal gyrus, then to the entorhinal cortex and perforant pathway. The final stop on the Papez circuit is the hippocampus. All of these sections are contained within the brain and, from start to finish, information travels through 12 sections, according to Papez's research. Neuroanatomy research that has occurred since 1937 suggests that the septum, amygdala, and prefrontal cortex are also part of this circuit. This additional research has also suggested that the amygdala plays a larger part than the hippocampus.

Damage or scarring to any one of the stops through the circuit can cause problems with Papez circuit function and with other parts, both within the pathway and on outside areas of the brain. If the amygdala is damaged, a person may have problems with responses to fear. Some people with hippocampal damage may have irregular or inhibited aggression responses. Anterior thalamic nuclei damage can cause spontaneous outbursts of emotion, such as crying or laughing, at odd times. People with lesions that affect the entorhinal cortex do not have normal interactions between the neocortex and the hippocampus.

The Papez circuit may have a bit of variation with some of the parts that are included, but most neuroanatomists agree that the function remains the same. The only real argument is about how the amygdala and other parts, from ongoing research results, fit in along the circuit's path. There are still many unanswered questions and so much that is unknown about how the human brain can function; continuous research keeps providing doctors and patients with new information about how emotions, memories, and responses are carried and stored in the brain.