Retinal projections in two crocodilian species, Caiman crocodilus and Crocodylus niloticus

Derobert, Yann; Médina, Monique; Rio, J.P.; Ward, Roger; Repérant, J; Marchand, M. J.; Miceli, D.

doi:10.1007/s004290050271

Cited by 23 publications

(25 citation statements)

References 45 publications

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“…RGCs project bilaterally with a contralateral dominance in most lizards, and projections are, on the whole, contralateral in crocodilians and completely contralateral in chameleons and uromastix lizards [Burns and Goodman, 1967;Repérant, 1975;Bennis et al, 1994;Tarpley et al, 1994;Ward et al, 1995;Derobert et al, 1999;Bruce, 2009]. Since these animals have little frontal use for their forelimbs, this is consistent with the EF hypothesis.…”

Section: Vp: In the Agamid Uromastix Acanthinurussupporting

confidence: 75%

Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination

Larsson

2011

Brain Behav Evol

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It is commonly proposed that the number of fibers that do not cross in the optic chiasm (OC) is proportional to the size of the binocular visual field, and that the major advantage of binocular vision is acute depth perception. I present an alternative, an ‘eye-forelimb’ (EF) hypothesis, suggesting that alterations in the OC influence the length of neural pathways that transmit visual information to motor nuclei and somatosensory areas involved in forelimb coordination. Evolutionary processes resulting in increased ipsilateral retinal projections (IRP) are of adaptive value in animals that regularly use the forelimbs in a frontal position, while evolutionary change towards reduced IRP is of value for animals that mainly use the forelimbs in lateral positions. Primates and cats, to a large extent, use visually guided forelimb maneuvers, and both groups have high proportions of IRP. The fact that vertebrates’ IRP arise exclusively from the temporal retina supports the hypothesis, since IRP from the nasal retina would increase the length of neural pathways involved in forelimb coordination. The EF hypothesis offers new perspectives on why a high proportion of IRP among early limbless vertebrates became reduced during the evolution of laterally situated limbs, and why reptiles that lost their limbs (snakes) evolved more IRP. Anatomical, neurophysiological, phylogenetic, ontogenetic and ecological data suggest that mutations changing the proportions of ipsilateral visual connections in the OC may have selective value for EF coordination.

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Section: Vp: In the Agamid Uromastix Acanthinurussupporting

confidence: 75%

Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination

Larsson

2011

Brain Behav Evol

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“…RITC has been used to study the neural connections of the visual system in different animal species by injection into the vitreous. 18,25,26 It is a fluorescent tracer that is incorporated into proteins and is transported in both anterograde and retrograde directions by axonal transport. 27 It has the advantage of being visualized by fluorescent methods and permits labeling of other structures within the same tissue by using immunohistochemical techniques.…”

Section: Discussionmentioning

confidence: 99%

Axonal Transport and Cytoskeletal Changes in the Laminar Regions after Elevated Intraocular Pressure

Balaratnasingam¹,

Morgan²,

Bass³

et al. 2007

Invest. Ophthalmol. Vis. Sci.

117

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“…7A, 9A), which we call the vSCN, following the nomenclature of Cantwell and Cassone (2006). Interestingly, in the closest extant relatives of birds, the crocodiles, retinohypothalamic projections to both a lateral and a medial portion of the hypothalamus have been described (Derobert et al, 1999).…”

Section: Hypothalamusmentioning

confidence: 99%

The visual system of a Palaeognathous bird: Visual field, retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

Krabichler

Vega‐Zuniga

Morales

et al. 2014

J of Comparative Neurology

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Most systematic studies of the avian visual system have focused on Neognathous species, leaving virtually unexplored the Palaeognathae, comprised of the flightless ratites and the South American tinamous. We investigated the visual field, the retinal topography, and the pattern of retinal and centrifugal projections in the Chilean tinamou, a small Palaeognath of the family Tinamidae. The tinamou has a panoramic visual field with a small frontal binocular overlap of 20°. The retina possesses three distinct topographic specializations: a horizontal visual streak, a dorsotemporal area, and an area centralis with a shallow fovea. The maximum ganglion cell density is 61,900/ mm(2) , comparable to Falconiformes. This would provide a maximal visual acuity of 14.0 cycles/degree, in spite of relatively small eyes. The central retinal projections generally conform to the characteristic arrangement observed in Neognathae, with well-differentiated contralateral targets and very few ipsilateral fibers. The centrifugal visual system is composed of a considerable number of multipolar centrifugal neurons, resembling the "ectopic" neurons described in Neognathae. They form a diffuse nuclear structure, which may correspond to the ancestral condition shared with other sauropsids. A notable feature is the presence of terminals in deep tectal layers 11-13. These fibers may represent either a novel retinotectal pathway or collateral branches from centrifugal neurons projecting to the retina. Both types of connections have been described in chicken embryos. Our results widen the basis for comparative studies of the vertebrate visual system, stressing the conserved character of the visual projections' pattern within the avian clade.

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Retinal projections in two crocodilian species, Caiman crocodilus and Crocodylus niloticus

Cited by 23 publications

References 45 publications

Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination

Binocular Vision and Ipsilateral Retinal Projections in Relation to Eye and Forelimb Coordination

Axonal Transport and Cytoskeletal Changes in the Laminar Regions after Elevated Intraocular Pressure

The visual system of a Palaeognathous bird: Visual field, retinal topography and retino‐central connections in the Chilean Tinamou (Nothoprocta perdicaria)

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