Differential retinal origins of separate anatomical channels for pattern and motion vision in rabbit

Abstract

The most conspicuous feature of the rabbit retina is the visual streak that extends along the horizontal azimuth from the nasal margin to the temporal limit of the retina. We believe the streak processes movement vision and that the temporal region (area centralis) is responsible for pattern perception. Both anatomical and behavioural experiments were used to test this hypothesis. Behavioural measures of pattern vision in normal and chiasma-sectioned rabbits revealed both to have the same visual acuity. Using OKN as a measure of movement vision, normal rabbits showed both a directional and velocity-tuned response. The chiasma-sectioned rabbits, with only uncrossed fibre projections remaining, showed a total loss of movement detection. The injection of HRP into the vitreal chamber of one eye in normal rabbits revealed extensive uptake throughout the contralateral thalamus. In the ipsilateral thalamus, there was uptake solely from the ipsilateral retinal projection to a restricted wafer of the lateral geniculate nucleus (LGN). The chiasma cut rabbits showed a very different distribution of HRP in the thalamus. The uptake was restricted to a thin wafer of the LGN, with no contralateral uptake. Thus, the thalamic projections from the retinal area centralis were strictly segregated from the thalamic target areas for the visual streak without any overlap. These findings provide strong evidence for separate retinal origins with anatomically separate pathways for pattern and movement vision in the rabbit.

International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Nonproliferative and Proliferative Lesions of the Rabbit

“…Although not visible ophthalmoscopically, the visual streak is well developed in the rabbit 220 , 335 , 343 , 347 , 348 , 349 , 350 , 351 , 352 . Histologically, in typical sagittal sections, the rabbit visual streak is a discrete nasotemporal linear zone of increased ganglion cell density, located inferior to the optic nerve head and medullary rays 220 , 348 , 350 , 351 , 352 , 353 .…”

“…The area centralis is a specialized focus of increased ganglion cell density distinct from the linear visual streak which is present in the retina of many mammals 335 , 354 . Whether the rabbit possesses an area centralis is a subject of some controversy, with some authors 348 , 351 , 353 , but not others 217 , 350 reporting its presence.…”

Numerosity Perception in Peripheral Vision

“…This tendency to generalize and blend information is ecologically relevant, if we consider that one of the roles of peripheral vision is to monitor the environment for relevant changes while we use foveal vision to focus on the current task. For example, in rabbits, the upper peripheral visual field is particularly tuned for dark spots on blue skies signifying predator birds ( Levick, 1967 ; Steele-Russell et al, 2012 ). As humans, we need to cancel out redundant or predictable information in the periphery to save processing power and not be too easily distracted.…”