Functional implications of species differences in the size and morphology of the isthmo optic nucleus (ION) in birds

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dc.contributor.authorGutierrez-Ibanez, Cristian I.
dc.contributor.authorIwaniuk, Andrew N.
dc.contributor.authorLisney, Thomas J.
dc.contributor.authorFaunes, Macarena
dc.contributor.authorMarin, Gonzalo J.
dc.contributor.authorWylie, Douglas R.
dc.date.accessioned2016-11-15T19:59:43Z
dc.date.available2016-11-15T19:59:43Z
dc.date.issued2013
dc.descriptionSherpa Romeo green journal: open accessen_US
dc.description.abstractIn birds, there is a retinofugal projection from the brain to the retina originating from the isthmo optic nucleus (ION) in the midbrain. Despite a large number of anatomical, physiological and histochemical studies, the function of this retinofugal system remains unclear. Several functions have been proposed including: gaze stabilization, pecking behavior, dark adaptation, shifting attention, and detection of aerial predators. This nucleus varies in size and organization among some species, but the relative size and morphology of the ION has not been systematically studied. Here, we present a comparison of the relative size and morphology of the ION in 81 species of birds, representing 17 different orders. Our results show that several orders of birds, besides those previously reported, have a large, well-organized ION, including: hummingbirds, woodpeckers, coots and allies, and kingfishers. At the other end of the spectrum, parrots, herons, waterfowl, owls and diurnal raptors have relatively small ION volumes. ION also appears to be absent or unrecognizable is several taxa, including one of the basal avian groups, the tinamous, which suggests that the ION may have evolved only in the more modern group of birds, Neognathae. Finally, we demonstrate that evolutionary changes in the relative size and the cytoarchitectonic organization of ION have occurred largely independent of phylogeny. The large relative size of the ION in orders with very different lifestyles and feeding behaviors suggest there is no clear association with pecking behavior or predator detection. Instead, our results suggest that the ION is more complex and enlarged in birds that have eyes that are emmetropic in some parts of the visual field and myopic in others. We therefore posit that the ION is involved in switching attention between two parts of the retina i.e. from an emmetropic to a myopic part of the retina.en_US
dc.description.peer-reviewYesen_US
dc.identifier.citationGutierrez-Ibanez, C., Iwaniuk, A. N., Lisney, T. J., Faunes, M., Marin, G. J., & Wylie, D. R. (2012). Functional implications of species differences in the size and morphology of the isthmo optic nucleus (ION) in birds. PLoS ONE, 7(5), e37816. doi:10.1371/journal.pone.0037816en_US
dc.identifier.urihttps://hdl.handle.net/10133/4695
dc.language.isoen_CAen_US
dc.publisherPublic Library of Scienceen_US
dc.publisher.departmentDepartment of Neuroscienceen_US
dc.publisher.facultyArts and Scienceen_US
dc.publisher.institutionUniversity of Albertaen_US
dc.publisher.institutionUniversity of Lethbridgeen_US
dc.publisher.institutionUniversidad de Chileen_US
dc.publisher.institutionUniversidad Finis Terraeen_US
dc.subjectIsthmo optic nucleusen_US
dc.subjectIONen_US
dc.subjectSpecies differencesen_US
dc.subjectBirdsen_US
dc.subjectRetinofugal pathwaysen_US
dc.subjectRetinaen_US
dc.titleFunctional implications of species differences in the size and morphology of the isthmo optic nucleus (ION) in birdsen_US
dc.typeArticleen_US
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