Papez circuit, illustration. The Papez circuit describes the connections between several areas of the brain. This loop begins with sensory inputs to the hippocampus that travel via the fornix to the mammillary body, through the anterior nucleus of the thalamus to the cingulate gyrus 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.