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Visual phototransduction is the sensory transduction process of the visual system by which light is detected by photoreceptor cells (rods and cones) in the vertebrate retina.A photon is absorbed by a retinal chromophore (each bound to an opsin), which initiates a signal cascade through several intermediate cells, then through the retinal ganglion cells (RGCs) comprising the optic nerve.
An opsin absorbs a photon (a particle of light) and transmits a signal to the cell through a signal transduction pathway, resulting in hyper-polarization of the photoreceptor. Rods and cones differ in function. Rods are found primarily in the periphery of the retina and are used to see at low levels of light. Each human eye contains 120 million ...
Neural pathway of the vestibular system. The vestibular nuclei on either side of the brainstem exchange signals regarding movement and body position. These signals are sent down the following projection pathways. To the cerebellum. Signals sent to the cerebellum are relayed back as muscle movements of the head, eyes, and posture.
The process of converting light energy into a meaningful image is a complex process that is facilitated by numerous brain structures and higher level cognitive processes. On an anatomical level, light energy first enters the eye through the cornea, where the light is bent.
The visual system and the somatosensory system are active even during resting state fMRI Activation and response in the sensory nervous system. The sensory nervous system is a part of the nervous system responsible for processing sensory information.
The VOR does not depend on what is seen. It can also be activated by hot or cold stimulation of the inner ear, where the vestibular system sits, and works even in total darkness or when the eyes are closed. However, in the presence of light, the fixation reflex is also added to the movement. [2]
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Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [7] Most vertebrate photoreceptors are located in the retina. The distribution of rods and cones (and classes thereof) in the retina is called the retinal mosaic. Each human retina has approximately 6 million cones and 120 million rods. [8]