Figure 5. A schematic drawing of the differential and common pathways of DRN (red) and MRN (yellow). The MRN projects very heavily to both hippocampus and cortex, but not to the striatum, while the DRN projects very heavily to striatum and cortex, but sparsely to septal pole of the hippocampus. When the fibers from one nucleus are destroyed, the 5-HT fibers from the other nucleus will sprout into the vacated territory (11,12).