Comparative Study of Photoreceptor and Retinal Ganglion Cell Topography and Spatial Resolving Power in Dipsadidae Snakes

Author(s)

Hauzman, Einat ^{[1, 2]} ; Bonci, Daniela M. O. ^{[1, 2]} ; Grotzner, Sonia R. ^[3] ; Mela, Maritana ^[3] ; Liber, Andre M. P. ^{[1, 2]} ; Martins, Sonia L. ^{[1, 2]} ; Ventura, Dora F. ^{[1, 2]}

Affiliation

^[1] Univ Sao Paulo, Inst Psicol, Dept Psicol, BR-05508030 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Nucleo Neurociencias & Comportamento, BR-05508030 Sao Paulo - Brazil

^[3] Univ Fed Parana, Dept Biol Celular, BR-80060000 Curitiba, Parana - Brazil

• Document type: Journal article
• Source: BRAIN BEHAVIOR AND EVOLUTION; v. 84, n. 3, p. 197-213, 2014.
• Web of Science Citations: 5

Abstract

The diurnal Dipsadidae snakes Philodryas olfersii and P. patagoniensis are closely related in their phylogeny but inhabit different ecological niches. P. olfersii is arboreal, whereas P. patagoniensis is preferentially terrestrial. The goal of the present study was to compare the density and topography of neurons, photoreceptors, and cells in the ganglion cell layer in the retinas of these two species using immunohistochemistry and Nissl staining procedures and estimate the spatial resolving power of their eyes based on the ganglion cell peak density. Four morphologically distinct types of cones were observed by scanning electron microscopy, 3 of which were labeled with anti-opsin antibodies: large single cones and double cones labeled by the antibody JH492 and small single cones labeled by the antibody JH455. The average densities of photoreceptors and neurons in the ganglion cell layer were similar in both species (similar to 10,000 and 7,000 cells.mm(-2), respectively). The estimated spatial resolving power was also similar, ranging from 2.4 to 2.7 cycles.degree(-1). However, the distribution of neurons had different specializations. In the arboreal P. olfersii, the isodensity maps had a horizontal visual streak, with a peak density in the central region and a lower density in the dorsal retina. This organization might be relevant for locomotion and hunting behavior in the arboreal layer. In the terrestrial P. patagoniensis, a concentric pattern of decreasing cell density emanated from an area centralis located in the naso-ventral retina. Lower densities were observed in the dorsal region. The ventrally high density improves the resolution in the superior visual field and may be an important adaptation for terrestrial snakes to perceive the approach of predators from above. (C) 2014 S. Karger AG, Basel (AU)

• FAPESP's process: 08/58731-2 - Vision as a sensitive indicator of conditions threatening retinal and central nervous system function
• Grantee: Dora Selma Fix Ventura
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/17423-6 - Study of the visual pigments of New World primates and analysis of genetic markers for diabetic retinopathy
• Grantee: Daniela Maria Oliveira Bonci
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 09/06026-6 - Psychophysical and genetic study of color vision deficiency in humans with different pathologies
• Grantee: Dora Selma Fix Ventura
• Support Opportunities: Regular Research Grants