ganglion cells and their support cells contain the optic nerve. The optic nerve receives a visual signal in orbit and moves back and forth through the visual channel. Then it leads to fiber. At this point, the fibers from the temporal fields are broken up. The fibers then pass through optical paths. Most of the axons of the optic nerve end in the lateral nucleus. Some other axons end in the suprachining nucleus, an area in which light is used to regulate the sleep and wake cycle. From the lateral nucleus, two optical irradiations, one temporal and one occipital, transmit visual information to the original visual cortex of the occipital lobe.


ganglion cells function


Retinal ganglion cells function (RGC) encode various features of the visual environment and send this information to the brain where they are processed for perception and behavior. RGC connections are extremely precise to ensure accurate visual processing. For example, neighboring RGCs project on neighboring parts of their targets and thus provide information about the spatial location of objects in the environment. Moreover, different RGCs functionally display different depths or “layers” within their targets, thereby establishing parallel circuits for analyzing various visual scene features such as motion, color or brightness. From a developmental perspective, each component of eye-brain communication translates into a different requirement for axon development, pathfinding, and target recognition during development.


Thus, understanding the full sequence of events that enable RGC to link to their goals is crucial not only for understanding the genesis of vision, but also a comprehensive model to examine how complex neuron circuits are built. Here we review studies focusing on how mammalian RGCs establish precise synaptic connections in the brain. In this way, we often mention experiments carried out on lower vertebrates and Drosophila, because they constitute a conceptual framework for thinking about cellular and molecular mechanisms that generate the specificity of a circumference. In this review, we also highlight important aspects of eye development from the brain to mammals that remain poorly understood, in the hope that our readers will be inspired to design and implement experiments to clarify them.



Distribution of retinal ganglion cells


Retinal ganglion cells function are relatively evenly distributed in the retina of the rat, density ranges from 3,000 cells per mm2 in the area of ​​the highest density (central region) to 600 cells per mm2 in the peripheral retina. The dimensions of dendritic retinal ganglion cells located in the central region do not differ significantly from their peripheral counterparts (Perry, 1979, Dreher et al., 1984, Sun et al., 2002b).


A flat density gradient raises the question of whether exploratory fixation – eye movement to obtain an image of an object of interest in a high-resolution region – occurs in rats. In rats, as in mammals with well-developed exploratory eye movements (eg Cats or primate), stimulation of the upper sternum (SC) induces coupled saccadic movements of the eye and there is a clear relationship between the retinotopic map and the topographic representation of the eye movement fields in SC (McHaffie) and Stein, 1982). However, eye movements in freely moving rats are usually uncoupled, with particular emphasis on maintaining the top field of the binoculars, rather than perpetuating the target (Wallace et al., 2013).



Ganglion Cell Density and Behavioral Acuity


The eye of a rat with a hood is able to optimally solve the 12-minute angle of view (Hughes and Wässle, 1979). The maximum spatial resolution of the retinal ganglion cells adapted to the dark or light recorded from the visual path of a hooded rat, however, is only about 1.2 cycles/degree or about 25 minutes of viewing angle (Friedman and Green, 1982); this value is closer to behavioral focus measures (Birch and Jacobs, 1979, Prusky et al., 2002) and is consistent with 1.3 cycles/grade predicted from peak coil density (Dreher et al., 1984; Hess et al. ., 1985).


The absolute sensitivity thresholds for pigmented rats (-5.2 to -5,8 log cd / m2) are comparable to the mean absolute threshold for humans adapted to the dark (Walraven et al., 1990). The sampling depth of the ganglion cells system is, therefore, the border point supporting the borderline of the behavioral focus near the 1-2 cycle/degree. Albino rats exhibit less sensitivity to light and less behavioral focus compared to pigmented rats (Birch and Jacobs, 1979, Green et al., 1991, Prusky et al., 2002).

[post_grid id=”473″]