Morphology, projection pattern, and neurochemical identity of Cajal's “centrifugal neurons”: The cells of origin of the tectoventrogeniculate pathway in pigeon (Columba livia) and chicken (Gallus gallus)

Authors

  • Tomas Vega-Zuniga,

    Corresponding author
    1. Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
    • Correspondence to: Dr. Tomas Vega-Zuniga, Lehrstuhl für Zoologie, Technische Universität München, Liesel-Beckmann Str. 04, 85354 Freising, Germany. E-mail: tomas.vega-zuniga@tum.de

    Search for more papers by this author
  • Jorge Mpodozis,

    1. Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago de Chile, Chile
    Search for more papers by this author
  • Harvey J. Karten,

    1. Department of Neurosciences, School of Medicine, University of California San Diego, La Jolla, California, USA
    Search for more papers by this author
  • Gonzalo Marín,

    1. Laboratorio de Neurobiología y Biología del Conocer, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago de Chile, Chile
    2. Facultad de Medicina, Universidad Finis Terrae, Santiago de Chile, Chile
    Search for more papers by this author
  • Sarah Hain,

    1. Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
    Search for more papers by this author
  • Harald Luksch

    1. Lehrstuhl für Zoologie, Technische Universität München, Freising-Weihenstephan, Germany
    Search for more papers by this author

  • This article was published online on 19 April 2014. A production error was subsequently identified. This notice is included in the online version to indicate that it has been corrected on 26 April 2014.

ABSTRACT

The nucleus geniculatus lateralis pars ventralis (GLv) is a prominent retinal target in all amniotes. In birds, it is in receipt of a dense and topographically organized retinal projection. The GLv is also the target of substantial and topographically organized projections from the optic tectum and the visual wulst (hyperpallium). Tectal and retinal afferents terminate homotopically within the external GLv-neuropil. Efferents from the GLv follow a descending course through the tegmentum and can be traced into the medial pontine nucleus. At present, the cells of origin of the Tecto-GLv projection are only partially described. Here we characterized the laminar location, morphology, projection pattern, and neurochemical identity of these cells by means of neural tracer injections and intracellular fillings in slice preparations and extracellular tracer injections in vivo. The Tecto-GLv projection arises from a distinct subset of layer 10 bipolar neurons, whose apical dendrites show a complex transverse arborization at the level of layer 7. Axons of these bipolar cells arise from the apical dendrites and follow a course through the optic tract to finally form very fine and restricted terminal endings inside the GLv-neuropil. Double-label experiments showed that these bipolar cells were choline acetyltransferase (ChAT)-immunoreactive. Our results strongly suggest that Tecto-GLv neurons form a pathway by which integrated tectal activity rapidly feeds back to the GLv and exerts a focal cholinergic modulation of incoming retinal inputs. J. Comp. Neurol. 522:2377–2396, 2014. © 2014 Wiley Periodicals, Inc.

Ancillary