The retinal projection to the nucleus lentiformis mesencephali in zebra finch (Taeniopygia guttata) and Anna’s hummingbird (Calypte anna)
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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. In both pigeons and chickens, retinal inputs to the nBOR arise from displaced ganglion cells (DGCs), which are found at the margin of the inner nuclear and inner plexiform layers. The LM receives afferents from retinal ganglion cells, but whether DGCs also project to LM is a matter of debate. Previous work in chickens had concluded that DGCs do not project to LM, but a recent study in pigeons found that both retinal ganglion cells and DGCs project to LM. These findings leave open the question of whether there are species differences with respect to the DGC projection to LM. In the present study, we made small injections of retrograde tracer into the LM in a zebra finch and an Anna’s hummingbird. In both cases, retrogradely labeled retinal ganglion cells and DGCs were observed. These results suggest that a retinal input to the LM arising from DGCs is characteristic of most, if not all, birds.
KeywordsDisplaced ganglion cells Optic flow Optokinetic Accessory optic system Nucleus of the basal optic root
Displaced ganglion cell
Ganglion cell layer
Lateral geniculate nucleus, pars ventralis
Inner nuclear layer
Inner plexiform layer
Nucleus lentiformis mesencephali pars medialis/lateralis
Nucleus of the basal optic root
Outer nuclear layer
Outer plexiform layer
Retinal ganglion cell
We would like to thank Melissa Armstrong Rebecca Long for help with this study.
All authors had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: CG-I, AHG, DLA, DRW. Acquisition of data CG-I, AHG, MRD, DRW. Analysis and interpretation of data: CG-I, AHG, MRD, DLA, DRW. Drafting of the article: CG-I. Critical revision of the article for important intellectual content: CG-I, AHG, DLA, DRW. Obtained funding: DLA, DRW. Study supervision: DLA, DRW.
This research was supported by funding to D.R.W. and D.L.A. from the Natural Sciences and Engineering Research Council of Canada (NSERC).
Compliance with ethical standards
Conflict of interest
The authors have no conflict of interest.
All experimental procedures were approved by the University of British Columbia Animal Care Committee in accordance with the guidelines set out by the Canadian Council on Animal Care.
- Grasse K, Cynader M (1990) The accessory optic system in frontal-eyed animals. In: Leventhal A (ed) Vision and visual dysfunction. The neuronal basis of visual function, vol IV. MacMillan, New York, pp 111–139Google Scholar
- Miceli D, Gioanni H, Reperant J, Peyrichoux J (1979) The avian visual Wulst: I. An anatomical study of afferent and efferent pathways. II. An electrophysiological study of the functional properties of single. In: Granda A, Maxwel J (eds) Neural mechanisms of behavior of the pigeon. Plenum Press, New York, pp 223–354Google Scholar