How does the feeling of sight work?
Review begins when photons from the world hit the lens of our eye and focus on a small spot of photorecement cells on a part of the eye called retina. These cells come in two types - bars and cones. The cones are for color detection, they work well in bright light and the bars are more sensitive, but also colors. People have about 125 million rod cells and 6 million conical cells. Some species have many more rods, especially those that are adapted to life at night. Some owls have a night vision 100 times acute than that we are used to.
The rods and cones perform a function called Phototransduction, which simply means converting incoming light into electrical signals to be sent to the brain, allowing a view. All these cells contain photoreceptive proteins with different pigment molecules. They are called rhodopsin. Various pigments can be found in the cone, allowing the eye to distinguish between different colors. When Light associated with a pigment affects the photorEceptor cell, sends an optical fiber signal, otherwise it is not. Photoreceptor cells and visual ability are extremely old evolutionary innovations that date back to the Cambrian period more than 540 million years ago.
There are two remarkable structural properties of human retina. The first is fovea, a highly condensed area of photoreceptor cells located in the center of the retina. The density of cells is several times larger than the periphery and explains why, when we look directly at something, it is much clearer than to look at it over the corner of the eye.
Fovea is also responsible for adaptation to behavior that evokes us to quickly turn our heads and stare at something if it surprises us. If Fovea did not exist and the photoreceptor density was even over the surface of the retina, we would not have to do it - we would have to turn the head slightly to at least fall into our field of vision.The foveal area is a relatively small part of the field of view, about 10 degrees wide.
The second remarkable structural characteristic in the retina is our blind spot. This is where the optical fiber is joined to the back of the retina to obtain visual information and exclude the existence of photoreceptors in a small place. Our brains automatically fill our blind spots for us, but various visual exercises can prove that it is there.
Once the light is converted into electrical pulses and an optical fiber sent, it goes to the back of the brain (after several stops) where the visual bark is located. In the visual bark, the hierarchy of detector cells isolated useful regularity in visual data and discards unnecessary information. One layer of cells detects things like lines and curves.
Higher Layer would detect regularity such as movement and 3D shapes. The highest layer is the place where the gestalts - total symbols - responsible for the conscious experience of sight for normal oof the bolts. The visual cortex is one of the best understood from all areas of the brain with bulky neuroscience literature.