(a) Left, targeting scheme for the GCaMP6s. Centre, localization of GCaMP6s. 3V, third ventricle; Arc, arcuate nucleus; D, dorsal; L, lateral; LH, lateral hypothalamus; M, medial; VMH, ventromedial hypothalamus, V, ventral. Scale bar, 500 μm. Right, GCaMP6s in Agrp cells at higher zoom. Representative example from 10 brains. Scale bar, 30 μm. (b) GCaMP6s response of Agrp cells (n=17) to EtOH (top), corresponding means±s.e.m. (bottom). (c) Relation between EtOH concentration and peak GCaMP6s response of Agrp cells (from experiments such as shown in b), n=12–17 cells for each concentration. One-sample t-tests: 1 mM, t=9.727, d.f.=16; 50 mM, t=8.794, d.f.=11; 100 mM, t=12.64, d.f.=15; ***P<0.0001.