a, AGRP neurons from Agrp-ires-cre;lsl-halorhodopsin (halorhodopsin is expressed as a fusion protein with YFP) or Agrp-ires-cre;lsl-tdTomato mice were dissociated and responses to light (LED-ON) were measured by whole-cell current clamp recordings. Representative examples (left) and the number of spikes measured (right) across cells from different mice before, during and after photostimulation with normalization to the pre-illumination period. n = 6 cells, data are mean ± s.e.m., lines represent individual cells. *P < 0.05 by two-tailed Wilcoxon test (P pink pre versus light: 0.03, P pink light versus post: 0.03, P grey pre versus light: 0.78, P grey light versus post: 0.38). An additional statistical test involving one-way ANOVA with Tukey’s multiple comparisons test revealed similar results (pink one-way ANOVA: P = 0.0003, with Tukey’s multiple comparisons test: pre versus light: P < 0.0001, light versus post: P < 0.001, grey one-way ANOVA: P = 0.53). b, Timeline and schematic based on published brain section images31 of optogenetic inhibition experiments in PVT. c, Investigation times in the two-choice behavioural assay during arcuate nucleus illumination in Agrp-ires-cre (control) or Agrp-ires-cre;lsl-halorhodopsin (ARC-OFF) mice. n = 6 mice, data are mean ± s.e.m., lines with triangles represent individual mice, *P < 0.05 by two-tailed Wilcoxon test (P control: 0.03; P ARC-OFF: 0.44). d, Food consumption after the two-choice odour test (Food 1 in timeline) in Agrp-ires-cre (control) or Agrp-ires-cre;lsl-halorhodopsin (ARC-OFF, PVT-OFF) mice during ARC (left) or PVT (right) illumination. n = 6 mice, mean ± s.e.m., lines with triangles represent individual mice. *P < 0.05, two-tailed Mann–Whitney U-test (P left: 0.015, P right: 0.57).