Mid-subjective day dark pulses activate orexin-A neurons in the tuberal hypothalamus. Photomicrographs illustrating c-Fos-ir and OXA-ir cells as well as c-Fos/OXA double-labeled cells within the TH. Panel (A) shows a low magnification representation of the regions shown in subsequent panels. Panel (B) shows OXA-ir cells (black arrows), a c-Fos-ir nucleus (blue arrow) and c-Fos/OXA double-labeled cells (red arrows) within the TH at high magnification. 3 V = third ventricle; lTH = lateral tuberal hypothalamus; mTH = medial tuberal hypothalamus; OPT = optic tract. Calibration bars = 100 μm (A), 10 μm (B), 25 μm (C-J).