RESEARCH ARTICLE The expression of tyrosine hydroxylase and DARPP-32 in the house crow (Corvus splendens) brain Shankhamala Sen 1 | Pooja Parishar 1 | Arvind Singh Pundir 1 | Anton Reiner 2,3 | Soumya Iyengar 1 1 Division of Systems Neuroscience, National Brain Research Centre, Gurugram, Haryana, India 2 Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States 3 Department of Ophthalmology, University of Tennessee, Memphis, Tennessee, United States Correspondence Soumya Iyengar, PhD, Professor and Scientist VI, Systems Neuroscience, National Brain Research Centre, NH-8, Manesar, Gurugram, Haryana 122052, India. Email: soumya@nbrc.ac.in Funding information Department of Science and Technology, Ministry of Science and Technology, Grant/ Award Number: SR/CSI/03/2010; National Brain Research Centre, Manesar, India ABSTRACT Birds of the family Corvidae which includes diverse species such as crows, rooks, ravens, mag- pies, jays, and jackdaws are known for their amazing abilities at problem-solving. Since the cate- cholaminergic system, especially the neurotransmitter dopamine, plays a role in cognition, we decided to study the distribution of tyrosine hydroxylase (TH), the rate-limiting enzyme in the synthesis of catecholamines in the brain of house crows (Corvus splendens). We also studied the expression of DARPP-32 (dopamine and cAMP-regulated phosphoprotein), which is expressed in dopaminoceptive neurons. Our results demonstrated that as in other avian species, the expression of both TH and DARPP-32 was highest in the house crow striatum. The caudolateral nidopallium (NCL, the avian analogue of the mammalian prefrontal cortex) could be differenti- ated from the surrounding pallial regions based on a larger number of TH-positive “baskets” of fibers around neurons in this region and greater intensity of DARPP-32 staining in the neuropil in this region. House crows also possessed distinct nuclei in their brains which corresponded to song control regions in other songbirds. Whereas immunoreactivity for TH was higher in the vocal control region Area X compared to the surrounding MSt (medial striatum) in house crows, staining in RA and HVC was not as prominent. Furthermore, the arcopallial song control regions RA (nucleus robustus arcopallialis) and AId (intermediate arcopallium) were strikingly negative for DARPP-32 staining, in contrast to the surrounding arcopallium. Patterns of immunoreactivity ABBREVIATIONS: (A4), location of A4 in other avian species; *A, putative A4 in house crows; A, arcopallium; AId, intermediate arcopallium; APHcl, caudolateral part of parahippocampal area; APHi, intermediate part of parahippocampal area; APHl, lateral part of parahippocampal area; APHm, medial part of parahippocampal area; Bas, nucleus basorostralis; BC, brachium conjunctivum (only in figure); BSTL, lateral part of bed nucleus of stria terminalis; BSTM, medial part of bed nucleus of stria terminalis; BSTMpa, pallial division of BSTM; BSTMpo, preoptic division of BSTM; CA, anterior commissure; Cb, cerebellum; CDL, dorsolateral corticoid area; Ceov, oval central nucleus; CO, optic chiasm; DG, dentate gyrus; DLL, nucleus dorsolateralis anterior, pars lateralis; DLM, nucleus dorsolateralis anterior, pars medialis; DLP (P), dorsolateral pallium; DLP, nucleus dorsolateralis anterior, pars posterior; DMA, nucleus dorsomedialis anterior; DNC, dorsomedial division of caudal nidopallium; DSV, ventral supraoptic decussation; DTZ, dorsal thalamic zone; E, entopallium; EAce, central extended amygdala; EAme, Medial extended amygdala; FA, fronto- arcopallial tract; FLM, fasciculus longitudinalis medialis; FPL, fasciculus prosencephali lateralis (lateral forebrain bundle); GCt, griseum centrale; GP, globus pallidus; HA, apical part of the hyperpallium; HD, densocellular part of the hyperpallium; Hi2, hippocampal area 2; HL, nucleus habenularis lateralis; HM, nucleus habenularis medialis; Hp, hippocampus; HVC, abbreviation used as formal name; Hy, hypothalamus; ICo, nucleus intercollicularis; IMc, nucleus isthmi, pars magnocellularis; INC, intermediate division of caudal nidopallium; INP, nucleus interpeduncularis; IO, nucleus isthmo-opticus; IPc, nucleus isthmi, pars parvocellularis; ITC, intercalated-like cell patches; ITCv, ventral part of the ITC; La, nucleus laminaris; LAD, lamina arcopallialis dorsalis; LaM, lamina Mesopallialis; LFS, lamina frontalis superior; LHy, lateral hypothalamus; LMAN, lateral magnocellular nucleus of the anterior nidopallium; lNCL, lateral part of caudolateral nidopallium; LoC, locus coeruleus; LPS, lamina pallio-subpallialis; LSt, lateral striatum; LV, lateral ventricle; M, mesopallium; Mc, nucleus magnocellularis; MeA, medial amygdala; MLd, nucleus mesencephalicus later- alis, pars dorsalis; mNCL, medial part of caudolateral nidopallium; MSt, medial striatum; MV, mesopallium ventrale; N, nidopallium; NAc, nucleus accumbens; NC, cau- dal nidopallium; NCL, caudolateral nidopallium; NCM, caudomedial nidopallium; NF, frontal nidopallium; nST, nucleus of the solitary tract; NIII, nervus oculomotorius; NVIII, nervus vestibulocochlearis; OM, tractus occipitomesencephalicus; OMN, oculomotor nucleus; OMv, nucleus nervii oculomotori, pars ventralis; POC, commis- sural part of preoptic area; PrV, nucleus sensorius principalis nervi trigemini; PT, pretectal nucleus; RA, robust nucleus of arcopallium; Rt, nucleus rotundus; S, septum; SCd, nucleus subceruleus dorsalis; SCv, nucleus subceruleus ventralis; SL, lateral septal nucleus; SLu, nucleus semilunaris; SM, medial septal nucleus; SN, substantia nigra; SNc, substantia nigra pars compacta; SNr, substantia nigra pars reticulata; SpA, subpallial amygdala; SpL, nucleus spiriformis lateralis; StC, striatal capsule; TeO, optic tectum; TFM, tractus thalamo-frontalis et frontalis-thalamicus medialis; TnA(P), nucleus taeniae of the amygdala; TD, nucleus tegmenti dorsalis; TTD, tractus descendens nervi trigemini; Uva, nucleus uvaeformis; V, ventricle; V4, fourth ventricle; VeD, nucleus vestibularis descendens; VeM, nucleus vestibularis medialis; VeS, nucleus vestibularis superioris; VNC, ventral division of caudal nidopallium; VTA, ventral tegmental area; X, area X. Shankhamala Sen and Pooja Parishar contributed equally to this study. Received: 5 April 2018 Revised: 22 January 2019 Accepted: 24 January 2019 DOI: 10.1002/cne.24649 J Comp Neurol. 2019;1–36. wileyonlinelibrary.com/journal/cne © 2019 Wiley Periodicals, Inc. 1