Fig. 6: c-Fos expression is greater than Arc expression and is independent of memory state in the PVT.

A Left: representative section (PVT in dotted outline) showing Arc (green) and c-Fos (magenta) expression with a Hoechst nuclear counterstain (blue). Right: inset, with Arc and c-Fos channels presented separately. White arrow: example Arc⁺c-Fos⁺ cell. B PVT c-Fos⁺ cell density was greater than that of Arc at every timepoint. C Arc⁺c-Fos⁻ cell density increased from no shock to encoding but decreased from encoding to 5-day retrieval. D Arc⁺c-Fos⁺ cell density increased only from the no shock to the encoding group. E Arc⁻c-Fos⁺ cell density did not differ across timepoints. F The density of the total number of PVT cells expressing Arc or c-Fos did not differ across timepoints. G The level of Arc⁺c-Fos⁺ co-labeling normalized to expected chance levels (dotted line) decreased from the no shock control group to every experimental timepoint. At each timepoint, mean co-labeling was above chance (one-sample t-tests, ***p = 0.0006, *p = 0.0323, ***p = 0.0003, and ***p = 0.0003 respectively). H–K Among complements of all labeled PVT cells, a greater proportion were Arc⁻c-Fos⁺ than Arc⁺c-Fos⁻ and than Arc⁺c-Fos⁺ at every timepoint. L All labeled PVT cells for each group, summed across all sections quantified for all mice, represented as a Venn diagram of Arc expression (green), c-Fos expression (magenta), and their overlap (blue) (n = 2494, n = 5977, n = 5075, and n = 6239 cells, respectively). Percentages of total cells in each complement are overlaid for each timepoint. N = 4 (no shock) or 8 (encoding, 1-day retrieval, 5-day retrieval) mice. Error bars indicate ±SEM. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001. PVT paraventricular nucleus of the thalamus, ∪ union.