Topographic specializations in the retinal ganglion cell layer of Australian passerines

Joao Coimbra, Shaun Collin, Nathan Hart

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Thornbills, honeyeaters, and silvereyes represent an abundant group of Australian passerines, whose diversity in niche differentiation suggests a pivotal role for vision. Using stereological methods and retinal wholemounts, we studied the topographic distribution of neurons in the ganglion cell layer of insectivorous, nectarivorous, and frugivorous species occupying terrestrial and arboreal microhabitats. All species studied have a central convexiclivate fovea (peak densities from 130,000 to 160,000 cells/mm2), which is shallow in the terrestrial/insectivorous yellow-rumped thornbill and deep in the arboreal/nectarivorous honeyeaters and frugivorous silvereye. Surrounding the fovea, neuronal densities in the ganglion cell layer form a broadly ovoid and asymmetric plateau in the yellow-rumped thornbill and a more restricted, circular and symmetric plateau in the other species. These differences in the plateau organization may reflect specific needs to locate food on the ground or among dense vegetation. We also found a temporal area (peak densities from 43,000 to 54,000 cells/mm2) across species, which increases spatial resolution in the frontal visual field and assists with foraging. Using microtubule-associated protein 2 (MAP2) immunohistochemistry, we detected a higher concentration of giant ganglion cells forming an area gigantocellularis in the temporal retina of all species. Giant ganglion cell densities also form a horizontal streak in all species, except in the yellow-rumped thornbill, which has an unusual increase toward the retinal periphery. In the yellow-rumped thornbill and silvereye, giant ganglion cells also peak in the nasal retina. We suggest that these topographic variations afford differential sampling of motion signals for the detection of predators. J. Comp. Neurol. 522:3609-3628, 2014. © 2014 Wiley Periodicals, Inc.
Original languageEnglish
Pages (from-to)3609-3628
Number of pages20
JournalJournal of Comparative Neurology
Volume522
Issue number16
Early online date10 Jun 2014
DOIs
Publication statusPublished - 1 Nov 2014

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Retinal Ganglion Cells
Ganglia
Giant Cells
Retina
Microtubule-Associated Proteins
Visual Fields
Nose
Cell Count
Immunohistochemistry
Neurons
Food

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title = "Topographic specializations in the retinal ganglion cell layer of Australian passerines",
abstract = "Thornbills, honeyeaters, and silvereyes represent an abundant group of Australian passerines, whose diversity in niche differentiation suggests a pivotal role for vision. Using stereological methods and retinal wholemounts, we studied the topographic distribution of neurons in the ganglion cell layer of insectivorous, nectarivorous, and frugivorous species occupying terrestrial and arboreal microhabitats. All species studied have a central convexiclivate fovea (peak densities from 130,000 to 160,000 cells/mm2), which is shallow in the terrestrial/insectivorous yellow-rumped thornbill and deep in the arboreal/nectarivorous honeyeaters and frugivorous silvereye. Surrounding the fovea, neuronal densities in the ganglion cell layer form a broadly ovoid and asymmetric plateau in the yellow-rumped thornbill and a more restricted, circular and symmetric plateau in the other species. These differences in the plateau organization may reflect specific needs to locate food on the ground or among dense vegetation. We also found a temporal area (peak densities from 43,000 to 54,000 cells/mm2) across species, which increases spatial resolution in the frontal visual field and assists with foraging. Using microtubule-associated protein 2 (MAP2) immunohistochemistry, we detected a higher concentration of giant ganglion cells forming an area gigantocellularis in the temporal retina of all species. Giant ganglion cell densities also form a horizontal streak in all species, except in the yellow-rumped thornbill, which has an unusual increase toward the retinal periphery. In the yellow-rumped thornbill and silvereye, giant ganglion cells also peak in the nasal retina. We suggest that these topographic variations afford differential sampling of motion signals for the detection of predators. J. Comp. Neurol. 522:3609-3628, 2014. {\circledC} 2014 Wiley Periodicals, Inc.",
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Topographic specializations in the retinal ganglion cell layer of Australian passerines. / Coimbra, Joao; Collin, Shaun; Hart, Nathan.

In: Journal of Comparative Neurology, Vol. 522, No. 16, 01.11.2014, p. 3609-3628.

Research output: Contribution to journalArticle

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