Tyrosine hydroxylase immunoreactive (TH-ir) cell groups in the zebra finch brain, shown from rostral (A15, panel A) to caudal (A8, panel H). Abbreviations: iii, 3rd ventricle; A12dl, A12 dorsolateral subdivision; A12vm, A12 ventromedial subdivision; ca, cerebral aqueduct; CG, central gray; HYP, hypothalamic; IP, interpeduncular nucleus; ME, median eminence; Niii, 3rd nerve; oc, optic chiasm; OM, occipitomesencephalic tract; ot, optic tract; POA, preoptic area; PVN, paraventricular nucleus; SN, substantia nigra; tsm, septomesencephalic tract; VTAc, caudal ventral tegmental area; VTAr, rostral ventral tegmental area; ZI, zona incerta. Scale bar denotes 500 μm.