Papez circuit, illustration. The Papez circuit describes the connections between several areas of the brain. This loop begins with sensory inputs (orange arrows) to the hippocampus (purple) that travel via the fornix (green) to the mammillary body (yellow), through the anterior nucleus of the thalamus (light blue) to the cingulate gyrus (mid blue) and then back to the hippocampus. When first discovered this neural circuit was believed to control emotional expression, but it is now thought that it has a larger role in memory, especially episodic memory.