a, Timeline and depiction of fibre photometry experiments during single-odour investigation, with schematic based on published brain section images31. Agrp-ires-cre mice were injected in the arcuate nucleus (ARC) with AAV-DIO-GCaMP6s, and fibre photometry was performed in the ARC, PVT or PVH during water investigation (Test A), pheromone investigation (Test B), food-odour investigation (Test C), and food consumption (Food 1). b, Top row, changes in GCaMP6s fluorescence (ΔF/F) were recorded by fibre photometry in brain regions indicated during single-odour investigation. Responses are depicted as the mean of measurements made in indicated time intervals (0–30 s, 30–60 s or each subsequent minute). n = 6 mice, mean ± s.e.m., *P < 0.05, **P < 0.01, ***P < 0.001, statistical comparisons between food odour and water responses by two-way ANOVA with Dunnett’s multiple comparison. Second row, food-odour investigation times per 30 s during fibre photometry measurements above at various time intervals (0–30 s, 30–60 s or each subsequent minute). n = 6 mice, data are mean ± s.e.m., lines represent individual mice. Third row, total investigation times for food odour, pheromones and water during 5-min fibre photometry test. n = 6 mice, data are mean ± s.e.m., lines with triangles represent individual mice, *P < 0.05 by two-tailed Wilcoxon test (P water versus pheromone: 0.03; P pheromone versus food odour: 0.03 for ARC, PVT, PVH). Bottom row, changes in GCaMP6s fluorescence (ΔF/F) were recorded by fibre photometry during food consumption (Food 1 in timeline of a) after odour tests in the same mice.