Step 3. An important circuit in the limbic system is the connection between the mammillary bodies and the hippocampus via the fornix, with the collaboration of the amygdala. This part of the limbic system is responsible for memory formation and the regulation of emotion (e.g. anxiety).

• Fornix (grey): Form two long tubes and place them against the mammillary body, then gently bend them towards the temporal horn of the ventricle.
• Hippocampus (light blue): Form two tubes, keeping one end slightly thicker. Place the thin part of the tube laterally to the temporal horn and against the fornix, then bend the hippocampus laterally over the temporal horn of the ventricle in a frontal direction.
• Amygdala (orange): Model two oval spheres and place them laterally on the frontal side of both hippocampi.