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Number and distribution of neurons in the retinal ganglion cell layer in relation to foraging behaviors of tyrant flycatchers

Authors

  • João Paulo Coimbra,

    Corresponding author
    1. Laboratório de Neuropatologia Experimental, Departamento de Fisiologia, Centro de Ciências Biológicas, Universidade Federal do Pará, UFPA, Belém, PA, Brazil
    • Laboratório de Neuropatologia Experimental, Hospital Universitário João de Barros Barreto, Departamento de Fisiologia, CCB, UFPA, Rua dos Mundurucus, 4487, Guamá – Belém-PA, Brazil – CEP: 66073000
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  • Nonata Trévia,

    1. Laboratório de Neuroanatomia Funcional, Departamento de Morfologia, Centro de Ciências Biológicas, Universidade Federal do Pará, UFPA, Belém, PA, Brazil
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  • Maria Luiza Videira Marceliano,

    1. Seção de Ornitologia, Departamento de Zoologia, Museu Paraense Emílio Goeldi, MPEG, Belém, PA, Brazil
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  • Belmira Lara da Silveira Andrade-Da-Costa,

    1. Laboratório de Neurofisiologia, Departamento de Fisiologia e Farmacologia, UFPE, Recife, PE, Brazil
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  • Cristovam Wanderley Picanço-Diniz,

    1. Laboratório de Neuroanatomia Funcional, Departamento de Morfologia, Centro de Ciências Biológicas, Universidade Federal do Pará, UFPA, Belém, PA, Brazil
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  • Elizabeth Sumi Yamada

    1. Laboratório de Neuropatologia Experimental, Departamento de Fisiologia, Centro de Ciências Biológicas, Universidade Federal do Pará, UFPA, Belém, PA, Brazil
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Abstract

The tyrant flycatchers represent a monophyletic radiation of predominantly insectivorous passerine birds that exhibit a plethora of stereotyped prey capture techniques. However, little is known about their retinal organization. Using retinal wholemounts, we estimated the total number and topography of neurons in the ganglion cell layer in the generalist yellow-bellied elaenia (Elaenia flavogaster) and the up-hover-gleaner mouse-colored tyrannulet (Phaeomyias murina) with the optical fractionator method. The mean estimated total number of neurons in the ganglion cell layer was 4,152,416 ± 189,310 in E. flavogaster and 2,965,132 ± 354,359 in P. murina. Topographic maps of isocounting lines revealed a similar distribution for both species: a central fovea and a temporal area surrounded by a poorly defined horizontal streak. In addition, both species had increased numbers of giant ganglion cells in the dorsotemporal retina forming an area giganto cellularis. In E. flavogaster, these giant ganglion cells were also distributed across the nasal and ventral retinal peripheries, which is in agreement with the generalist habits of this species. However, in P. murina these cells were rarely seen along the nasal and ventral peripheries, possibly reflecting a lesser need to perceive movement because this species captures stationary insects resting on foliage. Thus, we suggest that the retinas of the tyrant flycatchers in the present study show a general common pattern of neuron distribution in the ganglion cell layer irrespective of their foraging habits. We also suggest that the distribution of giant ganglion cells is indicative of the visual requirements of the species. J. Comp. Neurol. 514:66–73, 2009. © 2009 Wiley-Liss, Inc.

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