A new approach to location of the dentate gyrus and perforant path in rats/mice by landmarks on the skull.

The hippocampus has important roles in learning and memory. Many in vivo experiments require accurate location of a certain region of the hippocampus, long-term potentiation (LTP) recording being one of them. In vitro and in vivo studies can be used to measure LTP in the hippocampus. It is more difficult in vivo to locate the specific brain region than in vitro. Location of the dentate gyrus (DG) and perforant path (PP) is usually achieved using brain stereotaxic atlasses. Because the data in the atlasses were obtained from a particular rat/mouse strain (Rat: adult Wistar, 290 g; Mouse: adult C57BL/J6, 26-30 g), the data in atlases could not be easily applied in all the different other strains of these species. We describe a method that uses landmarks on the skull to locate these structures in both species, which has been successfully applied in BALB/c mice, KM mice, SAMP8, SAMR1 and Wistar rats; making it a reliable and useful means of locating the DG and PP.