Increase in Arc RNA expression in the dentate gyrus and CA3 regions 30 min after spatial water task training. a and c show nuclei (blue) and Arc RNA staining (red) for a caged control and a spatial water task-trained rat, respectively. b and dshow grayscale images of Arc RNA staining froma and c, respectively. Final magnification is 5×. Scale bars (shown in a andc): 200 μm. See Materials and Methods for experimental details and Table 4 for the summary of the quantitative analyses.