title: Retinal projection to the pretectal nucleus lentiformis mesencephali in pigeons (Columba livia).
abstract: In birds, the nucleus of the basal optic root (nBOR) and the nucleus lentiformis mesencephali (LM) are retinal-recipient nuclei involved in the analysis of optic flow and the generation of the optokinetic response. The nBOR receives retinal input from displaced ganglion cells (DGCs), which are found at the margin of the inner nuclear and inner plexiform layers, rather than the ganglion cell layer. The LM receives afferents from retinal ganglion cells, but whether DGCs also project to LM remains unclear. To resolve this issue, we made small injections of retrograde tracer into LM and examined horizontal sections through the retina. For comparison, we also had cases with injections in nBOR, the optic tectum, and the anterior dorsolateral thalamus (the equivalent to the mammalian lateral geniculate nucleus). From all LM injections both retinal ganglion cells and DGCs were labeled. The percentage of DGCs, as a proportion of all labeled cells, varied from 2-28%, and these were not different in morphology or size compared to those labeled from nBOR, in which the proportion of DGCs was much higher (84-93%). DGCs were also labeled after injections into the anterior dorsolateral thalamus. The proportion was small (2-3%), and these DGCs were smaller in size than those projecting to the nBOR and LM. No DGCs were labeled from an injection in the optic tectum. Based on an analysis of size, we suggest that different populations of retinal ganglion cells are involved in the projections to LM, nBOR, the optic tectum, and the anterior dorsolateral thalamus.
authors.affiliation: Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9; Department of Psychology, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Wylie
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kolominsky
authors.forename: David J
authors.initials: DJ
authors.lastname: Graham
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Lisney
authors.forename: Cristian
authors.initials: C
authors.lastname: Gutierrez-Ibanez
mesh_terms: D000818:Animals; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D001931:Brain Mapping; D002772:Cholera Toxin / Q000378:metabolism; D010856:Columbidae / Q000033:anatomy & histology*; D003911:Dextrans / Q000378:metabolism; D008636:Mesencephalon / Q000166:cytology*; D009474:Neurons / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D013477:Superior Colliculi; D014795:Visual Pathways / Q000502:physiology*
chemical_list: D003911:Dextrans; C076397:biotinylated dextran amine; D001710:Biotin; D002772:Cholera Toxin
keywords: RRID:rid_000096; accessory optic system; anterior dorsolateral thalamus; displaced ganglion cells; nucleus of the basal optic root; optic flow; optic tectum; optokinetic; retinal ganglion cells; visual motion