Fig. 1: vSUB projection to the VS is activated by training in the water maze.
a Schematic of the experimental design. Retrograde tracer Fluoro-Gold (FG) combined with fos was used to identify subicular VS-projecting cells activated by cue or spatial training in the MWM. MWM images modified from ref. 9; Image credit for brains schematics: Allen Institute. b Microphotographs showing FG injection site in the VS and VS projecting cells in the vSUB (cyan). Images are counterstained with the nuclear dye propidium iodide (red). Scale bar: 1 mm; coordinates from bregma (mm). c Representative images showing FG, fos labeling and the overlay of the two labeling in the vSUB (red arrows: fos; yellow arrows: co-labeling). Scale bar: 100 µm. d fos expression was significantly increased in the whole vSUB (F2,22 = 4.762, p = 0.0191), as well as in the subicular VS-projecting cells (F2,22 = 4.178, p = 0.0290), in both cue (C; n = 8) and spatial (S; n = 9) trained mice compared to naïve (N = naïve to training; n = 8). No difference was found among groups in the number of FG-positive cells (F2,22 = 1.023, p = 0.3762). Histograms represent mean ± SEM. *p < 0.05 vs naïve (Fisher).
