VISUAL SYSTEM
The visual system converts light into electrical signals that are processed by the brain to form a visual concept that we can interact with. For example, take a dog running in the park. Now imagine how the visual information of this scene is converted and processed to describe what we see. as light radiates from the sky To illuminate this scene, our eyes are busy absorbing reflected light rays from the grass and the dog as they move in front of us. This information first passes through our cornea and is focused by the lens so that a crisp snapshot is projected onto the retina.
The retina is light sensitive. It converts colors and light intensities into electrical signals that are sent to the brain for processing along the optic nerve. Because we have two eyes and stereo vision our brain has an interesting pathway to deliver visual information to be interpreted. From the eyes both optic nerves converge into the optic chiasm which splits information into left and right visual fields. This information is carried via the optic tracts to the lateral geniculate nuclei and finally back to the primary visual cortex.
The complexity of this pathway reveals the immense information taken in by the retina. Upon reaching the primary visual cortex the processing splits into two streams of information. The wear information moves upward into the dorsal stream and focuses on light intensity, which best characterizes motion.
The static dog information moves down into the ventral stream and focuses on features that characterize what something is. All this information works together to give us a mental picture of the world outside.
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