Papez Circuit

James Papez described the circuit which is involved in the cortical control of emotion in 1937.

It is also important in storing the Memory

Papez discovered the circuit after injecting Rabies virus into a cat's hippocampus and monitoring its progression through the brain.

The initial pathway described by Papez include

Hippocampal formation (Subiculum) → Fornix → Mammillary bodies → Mammillothalamic tract → Anterior thalamic nucleus → Genu of the internal capsule → Cingulate gyrus→ Cingulum → Parahippocampal gyrus → Entorhinal cortex → Perforant pathway → Hippocampus.

The Perforant pathway provides a connectional route from the entorhinal cortex to all fields of the hippocampal formation, including the dentate gyrus, all CA fields (including CA1),and the subiculum.

With newer inventions the Prefrontal cortex (PFC), Amygdala, and Septum are also included in the Papez circuit with the PFC and amygdala considered as the  key components.

The nuclei in the septum play a role in reward and reinforcement with the nucleus accumbens identified to have a key role as a pleasure center