title: An immunohistochemical and pathway tracing study of the striatopallidal organization of area X in the male zebra finch.
abstract: Area X is a nucleus within songbird basal ganglia that is part of the anterior forebrain song learning circuit. It receives cortical song-related input and projects to the dorsolateral medial nucleus of thalamus (DLM). We carried out single- and double-labeled immunohistochemical and pathway tracing studies in male zebra finch to characterize the cellular organization and circuitry of area X. We found that 5.4% of area X neuronal perikarya are relatively large, possess aspiny dendrites, and are rich in the pallidal neuron/striatal interneuron marker Lys8-Asn9-neurotensin8-13 (LANT6). Many of these perikarya were found to project to the DLM, and their traits suggest that they are pallidal. Area X also contained several neuron types characteristic of the striatum, including interneurons co-containing LANT6 and the striatal interneuron marker parvalbumin (2% of area X neurons), interneurons containing parvalbumin but not LANT6 (4.8%), cholinergic interneurons (1.4%), and neurons containing the striatal spiny projection neuron marker dopamine- and adenosine 3',5'-monophosphate-regulated phosphoprotein (DARPP-32) (30%). Area X was rich in substance P (SP)-containing terminals, and many ended on area X neurons projecting to the DLM with the woolly fiber morphology characteristic of striatopallidal terminals. Although SP+ perikarya were not detected in area X, prior studies suggest it is likely that SP-synthesizing neurons are present and the source of the SP+ input to area X neurons projecting to the DLM. Area X was poor in enkephalinergic fibers and perikarya. The present data support the premise that area X contains both striatal and pallidal neurons, with the striatal neurons likely to include SP+ neurons that project to the pallidal neurons.
authors.affiliation: Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA. areiner@utmem.edu
authors.forename: Anton
authors.initials: A
authors.lastname: Reiner
authors.forename: Antonio V
authors.initials: AV
authors.lastname: Laverghetta
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Meade
authors.forename: Sherry L
authors.initials: SL
authors.lastname: Cuthbertson
authors.forename: Sarah W
authors.initials: SW
authors.lastname: Bottjer
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D015415:Biomarkers; D003342:Corpus Striatum / Q000166:cytology* / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism / Q000648:ultrastructure; D004298:Dopamine / Q000378:metabolism; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004745:Enkephalins / Q000378:metabolism; D005917:Globus Pallidus / Q000166:cytology* / Q000378:metabolism; D007150:Immunohistochemistry; D007395:Interneurons / Q000378:metabolism / Q000648:ultrastructure; D007858:Learning / Q000502:physiology; D008297:Male; D009419:Nerve Tissue Proteins; D009434:Neural Pathways / Q000166:cytology* / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D012726:Sexual Behavior, Animal / Q000502:physiology; D020308:Songbirds / Q000033:anatomy & histology* / Q000502:physiology; D013373:Substance P / Q000378:metabolism; D013788:Thalamus / Q000166:cytology; D014828:Vocalization, Animal / Q000502:physiology
chemical_list: D015415:Biomarkers; D051937:Dopamine and cAMP-Regulated Phosphoprotein 32; D004745:Enkephalins; D009419:Nerve Tissue Proteins; D009842:Oligopeptides; D010320:Parvalbumins; D010750:Phosphoproteins; D013373:Substance P; C037243:neurotensin-related hexapeptide; D000109:Acetylcholine; D004298:Dopamine