Do American Goldfinches See Their World Like Passive Prey Foragers? A Study on Visual Fields, Retinal Topography, and Sensitivity of Photoreceptors

2014 ◽  
Vol 83 (3) ◽  
pp. 181-198 ◽  
Author(s):  
Patrice E. Baumhardt ◽  
Bret A. Moore ◽  
Megan Doppler ◽  
Esteban Fernández-Juricic
Keyword(s):  
Visual Fields ◽  
Retinal Topography

Retinal Topography in Two Species of Baleen Whale (Cetacea: Mysticeti)

2018 ◽  
Vol 92 (3-4) ◽  
pp. 97-116 ◽  
Author(s):  
Thomas J. Lisney ◽  
Shaun P. Collin
Keyword(s):  
Ganglion Cells ◽  
Feeding Strategy ◽  
Visual Fields ◽  
Humpback Whale ◽  
High Density ◽  
Resolving Power ◽  
Temporal Area ◽  
Baleen Whales ◽  
Axial Diameter ◽  
Retinal Topography

Little is known about the visual systems of large baleen whales (Mysticeti: Cetacea). In this study, we investigate eye morphology and the topographic distribution of retinal ganglion cells (RGCs) in two species of mysticete, Bryde’s whale (Balaenoptera edeni) and the humpback whale (Megaptera novaeanglia). Both species have large eyes characterised by a thickened cornea, a heavily thickened sclera, a highly vascularised fibro-adipose bundle surrounding the optic nerve at the back of the eye, and a reflective blue-green tapetum fibrosum. Using stereology and retinal whole mounts, we estimate a total of 274,268 and 161,371 RGCs in the Bryde’s whale and humpback whale retinas, respectively. Both species have a similar retinal topography, consisting of nasal and temporal areas of high RGC density, suggesting that having higher visual acuity in the anterior and latero-caudal visual fields is particularly important in these animals. The temporal area is larger in both species and contains the peak RGC densities (160 cells mm–2 in the humpback whale and 200 cells mm–2 in Bryde’s whale). In the Bryde’s whale retina, the two high-density areas are connected by a weak centro-ventral visual streak, but such a specialisation is not evident in the humpback whale. Measurements of RGC soma area reveal that although the RGCs in both species vary substantially in size, RGC soma area is inversely proportional to RGC density, with cells in the nasal and temporal high-density areas being relatively more homogeneous in size compared to the RGCs in the central retina and the dorsal and ventral retinal periphery. Some of the RGCs were very large, with soma areas of over 2,000 µm2. Using peak RGC density and eye axial diameter (Bryde’s whale: 63.5 mm; humpback whale: 48.5 mm), we estimated the peak anatomical spatial resolving power in water to be 4.8 cycles/degree and 3.3 cycles/degree in the Bryde’s whale and the humpback whale, respectively. Overall, our findings for these two species are very similar to those reported for other species of cetaceans. This indicates that, irrespective of the significant differences in body size and shape, behavioural ecology and feeding strategy between mysticetes and odontocetes (toothed whales), cetacean eyes are adapted to vision in dim light and adhere to a common “bauplan” that evolved prior to the divergence of the two cetacean parvorders (Odontoceti and Mysticeti) over 30 million years ago.

scholarly journals Eye Morphology and Retinal Topography in Hummingbirds (Trochilidae: Aves)

2015 ◽  
Vol 86 (3-4) ◽  
pp. 176-190 ◽  
Author(s):  
Thomas J. Lisney ◽  
Douglas R. Wylie ◽  
Jeffrey Kolominsky ◽  
Andrew N. Iwaniuk
Keyword(s):  
Visual Fields ◽  
High Density ◽  
Resolving Power ◽  
Transverse Diameter ◽  
Density Region ◽  
Temporal Area ◽  
Eye Morphology ◽  
Neuron Density ◽  
Retinal Topography ◽  
Central High

Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ∼45,000 cells·mm-2, and a temporal area with lower densities (38,000-39,000 cells·mm-2). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cycles·degree-1. Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects.

Semantic Priming by Pictures in Lexical Decisions in Visual Fields

2010 ◽  
Author(s):  
Linda Netherland ◽  
Daniel J. Schmoller ◽  
Quintino R. Mano ◽  
David C. Osmon
Keyword(s):  
Semantic Priming ◽  
Visual Fields ◽  
Lexical Decisions

Machines, Nations, and Faciality

2019 ◽  
pp. 156-193
Author(s):  
Serguei Alex Oushakine
Keyword(s):  
Elementary School ◽  
School Children ◽  
Industrial Production ◽  
Political Development ◽  
Elementary School Children ◽  
Visual Fields ◽  
Dual Process ◽  
Dual Nature ◽  
Soviet Russia ◽  
Visual Regimes

This article explores illustrated children’s books that were published in Soviet Russia during the first five-year plan (1928–1932). Targeting mostly preschool and elementary school children, these books are creatively illustrated, offering their readers highly detailed accounts of economic and political development in the country. Soviet pedagogues perceived this literature as a tool for training “literate spectators,” able to discern social and political importance of images. The article follows this idea, using the books for tracing visual regimes that represented class and ethnicity in the 1920s–1930s. Picture books for children successfully reflected the dual nature of socialist transformations in the USSR, where building new sites of industrial production were closely linked with the building of new nations. Very early on, this literature also documented the bifurcation of this dual process. The detailed portrayal of ethnic distinctions was paralleled by the visual disappearance of the working class, producing a stream of illustrations in which technology and ethnic groups emerged as self-sufficient visual fields, ostensibly disconnected from class, labor, and history.

Visual Field Accuracy and Eye Movement Direction: A Child's Eye View

1980 ◽  
Vol 50 (2) ◽  
pp. 631-636
Author(s):  
Evans Mandes
Keyword(s):  
Eye Movements ◽  
Visual Field ◽  
Eye Movement ◽  
Visual Fields ◽  
Movement Direction

Post-exposural eye movements were studied in 32 adults and 24 7-yr.-old children. Stimuli were binary figures exposed tachistoscopically in both visual fields simultaneously. The data showed significant correlations between direction of eye movement and locus of recognition for both children and adults. No significant differences were found in frequencies of eye movements of children and adults. The data are interpreted in terms of the facilitative effects of post-exposural eye movements upon perception for both groups.

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