The term limbic circuit refers to neural circuitry linking structures of the limbic lobe and interbrain to form a closed linear reverberating circuit that mediates emotional states originating in the hypothalamus and maintained as memory functions of the hippocampal formation. Originally defined by James Papez on the basis of neuroanatomical studies by Paul Broca, it has been described by various authors as containing or excluding certain of the substructures ( Anthoney-1994 ). In the basic description, neurons in the medial mammillary nucleus of the hypothalamus project via the mammillothalamic tract to the anterior nuclear group of the thalamus. Neurons there project to the cingulate gyrus, from which neurons in turn project to the CA fields via the cingulum or entorhinal cortex. Fibers arising from the CA fields course through the fornix to the hypothalamus, closing the circuit ( Carpenter-1983 ). Laterr authors have expanded the concept to include several areas of the frontal lobe and temporal lobe to form a network of structures serving emotional and memory functions ( Kamali-2023 ). Updated 19 May 2024.