title: Microconnectomics of the pretectum and ventral thalamus in the chicken (Gallus gallus).
abstract: The avian pretectal and ventrothalamic nuclei, encompassing the griseum tectale (GT), n. lentiformis mesencephali (LM), and n. geniculatus lateralis pars ventralis (GLv), are prominent retinorecipient structures related to optic flow operations and visuomotor control. Hence, a close coordination of these neural circuits is to be expected. Yet the connectivity among these nuclei is poorly known. Here, using intracellular labeling and in situ hybridization, we investigated the detailed morphology, connectivity, and neurochemical identity of neurons in these nuclei. Two different cell types exist in the GT: one that generates an axonal projection to the optic tectum (TeO), LM, GLv, and n. intercalatus thalami (ICT), and a second population that only projects to the LM and GLv. In situ hybridization revealed that most neurons in the GT express the vesicular glutamate transporter (VGluT2) mRNA, indicating a glutamatergic identity. In the LM, three morphological cell types were defined, two of which project axons towards dorsal targets. The LM neurons showed strong VGluT2 expression. Finally, the cells located in the GLv project to the TeO, LM, GT, n. principalis precommisuralis (PPC), and ICT. All neurons in the GLv showed strong expression of the vesicular inhibitory amino acid transporter (VIAAT) mRNA, suggesting a GABAergic identity. Our results show that the pretectal and ventrothalamic nuclei are highly interconnected, especially by glutamatergic and GABAergic neurons from the GT and GLv, respectively. This complex morphology and connectivity might be required to organize orienting visuomotor behaviors and coordinate the specific optic flow patterns that they induce. J. Comp. Neurol. 524:2208-2229, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Tomas
authors.initials: T
authors.lastname: Vega-Zuniga
authors.affiliation: Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.|Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Marín
authors.affiliation: Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: Cristian
authors.initials: C
authors.lastname: González-Cabrera
authors.affiliation: Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Planitscher
authors.affiliation: Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Hartmann
authors.affiliation: Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Marks
authors.affiliation: Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
authors.forename: Jorge
authors.initials: J
authors.lastname: Mpodozis
authors.affiliation: Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Luksch
mesh_terms: D000818:Animals; D002645:Chickens; D017403:In Situ Hybridization; D009474:Neurons / Q000166:cytology; D066250:Pretectal Region / Q000166:cytology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013788:Thalamus / Q000166:cytology*; D014795:Visual Pathways / Q000166:cytology*
keywords: GLv; GT; ICT; LM; RRID:OMICS_02343; RRID:nlx_84100; RRID:nlx_84530; biocytin; birds; neurochemistry; slice