Are Avian Retinal Oil Droplets Optically Adapted To Enhance Light Collection In Cone Outer Segments?

Abstract

Event Abstract Back to Event Are Avian Retinal Oil Droplets Optically Adapted To Enhance Light Collection In Cone Outer Segments? David Wilby1, 2, 3 and Nicholas Roberts1* 1 University of Bristol, School of Biological Sciences, United Kingdom 2 University of Bristol, School of Physics, United Kingdom 3 University of Bristol, Bristol Centre for Functional Nanomaterials, United Kingdom Cone photoreceptors of around half of the vertebrate orders contain spherical optical structures known as oil droplets. These form at the junction between the inner and outer segments. Around half of these oil droplets are also coloured and act as spectral filters, and are believed to improve behavioural colour discrimination. The spherical nature of some of these, in addition to the existence of transparent oil droplets in many vertebrates, implies some optical function beyond that of a filter. The central aim in this work was to determine whether oil droplets are optimised at sub-wavelength scales as a condensing lens to intensify the light field absorbed in cone sub-type. Birds have five types of cone photoreceptor which all have oil droplets, including the primary member of the double cone. In this work, we concentrate on avian cone photoreceptors to study the structure and function of the oil droplet. We present measurements from digital holographic microscopy of chicken retina and electromagnetic models of the spherical oil droplet. Optical phase data and polarisation microscopy suggest a more complex aniostropic structure than a simple isotropic sphere, the presumed structure until now. Digital holographic measurements were used to determine the spatial refractive index properties of the oil droplet. We use these results to inform a sub-wavelgenth scale optical model which has been modelled using electromagnetic frequency- domain finite element analysis. The effect of the oil droplet on the incident light is compared with the morphology of the photoreceptor to determine the evaluate the hypothesis of the oil droplet as a condensing optical element adapted to optimise light capture in each cone sub-type. References G.H. Jacobs, M.P. Rowe, Evolution of vertebrate colour vision, Clin. Exp. Optom., 87 (4-5), 206-216, 2004. N.S. Hart, The Visual Ecology of Avian Photoreceptors, Prog. Retin. Eye Res., 20 (5), 675-703, 2001. Keywords: Colour vision, low-light vision, nanophotonics, optics, photonics, Vision Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for participant symposium and student poster award) Topic: Sensory: Vision Citation: Wilby D and Roberts N (2012). Are Avian Retinal Oil Droplets Optically Adapted To Enhance Light Collection In Cone Outer Segments?. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00103 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Apr 2012; Published Online: 07 Jul 2012. * Correspondence: Dr. Nicholas Roberts, University of Bristol, School of Biological Sciences, Bristol, BS8 1UG, United Kingdom, nicholas.roberts@bristol.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers David Wilby Nicholas Roberts Google David Wilby Nicholas Roberts Google Scholar David Wilby Nicholas Roberts PubMed David Wilby Nicholas Roberts Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.