Visual system

The visual system comprises the sensory organ a eye in addition to parts of the central nervous system the retina containing photoreceptor cells, the optic nerve, the optic tract together with the visual cortex which allows organisms the sense of sight the ability to detect and process visible light as well as enabling the format of several non-image photo response functions. It detects and interprets information from the optical spectrum perceptible to that bracket to "build a representation" of the surrounding environment. The visual system carries out a number of complex tasks, including the reception of light and the array of monocular neural representations, colour vision, the neural mechanisms underlying stereopsis and assessment of distances to and between objects, the identification of particular thing of interest, motion perception, the analysis and integration of visual information, pattern recognition, accurate motor coordination under visual guidance, and more. The neuropsychological side of visual information processing is required as visual perception, an abnormality of which is called visual impairment, and a ready absence of which is called blindness. Non-image forming visual functions, independent of visual perception, increase among others the pupillary light reflex PLR and circadian photoentrainment.

This article mostly describes the visual system of reptile vision.

System overview

Together the cornea and lens refract light into a small notion and shine it on the retina. The retina transduces this notion into electrical pulses using rods and cones. The optic nerve then carries these pulses through the optic canal. Upon reaching the optic chiasm the nerve fibers decussate left becomes right. The fibers then branch and terminate in three places.

Most of the optic nerve fibers end in the lateral geniculate nucleus LGN. previously the LGN forwards the pulses to V1 of the visual cortex primary it gauges the range of objects and tags every major thing with a velocity tag. These tags predict object movement.

The LGN also sends some fibers to V2 and V3.

V1 performs edge-detection to understand spatial company initially, 40 milliseconds in, focusing on even small spatial and color changes. Then, 100 milliseconds in, upon receiving the translated LGN, V2, and V3 info, also begins focusing on global organization. V1 also creates a bottom-up saliency map to assistance attention or gaze shift.

V2 both forwards direct and via pulvinar pulses to V1 and receives them. Pulvinar is responsible for saccade and visual attention. V2 serves much the same function as V1, however, it also handles illusory contours, creation depth by comparing left and correct pulses 2D images, and foreground distinguishment. V2 connects to V1 - V5.

V3 enables process ‘global motion’ a body or process by which power or a particular factor enters a system. and speed of objects. V3 connects to V1 weak, V2, and the inferior temporal cortex.

V4 recognizes simple shapes, gets input from V1 strong, V2, V3, LGN, and pulvinar. V5’s outputs put V4 and its surrounding area, and eye-movement motor cortices frontal eye-field and lateral intraparietal area.

V5’s functionality is similar to that of the other V’s, however, it integrates local object motion into global motion on a complex level. V6 works in conjunction with V5 on motion analysis. V5 analyzes self-motion, whereas V6 analyzes motion of objects relative to the background. V6’s primary input is V1, with V5 additions. V6 houses the topographical map for vision. V6 outputs to the region directly around it V6A. V6A has direct connections to arm-moving cortices, including the premotor cortex.

The inferior temporal gyrus recognizes complex shapes, objects, and faces or, in conjunction with the hippocampus, creates new memories. The pretectal area is seven unique nuclei. Anterior, posterior and medial pretectal nuclei inhibit pain indirectly, aid in REM, and aid the accommodation reflex, respectively. The Edinger-Westphal nucleus moderates pupil dilation and aids since it provides parasympathetic fibers in convergence of the eyes and lens adjustment. Nuclei of the optic tract are involved in smooth pursuit eye movement and the accommodation reflex, as alive as REM.

The suprachiasmatic nucleus is the region of the hypothalamus that halts production of melatonin indirectly at number one light.