Nägemisradasid

Nägemisradasid, often translated as visual pathways, refers to the neural circuits responsible for transmitting visual information from the retina to the brain for processing. These pathways begin with photoreceptor cells in the retina, the rods and cones, which convert light into electrical signals. These signals are then processed by other neurons within the retina, including bipolar cells and ganglion cells. The axons of the ganglion cells form the optic nerve, which carries visual information out of the eye.

The optic nerves from each eye partially cross at the optic chiasm. Information from the nasal (inner) half of each retina crosses over to the opposite side of the brain, while information from the temporal (outer) half remains on the same side. This arrangement ensures that each hemisphere of the brain receives input from the contralateral visual field. After the optic chiasm, the nerve fibers are called the optic tracts.

The majority of optic tract fibers synapse in the lateral geniculate nucleus (LGN) of the thalamus. The LGN acts as a relay center, further processing and organizing visual information before transmitting it to the primary visual cortex (V1) located in the occipital lobe of the brain. From V1, visual information is then sent to other areas of the cerebral cortex for more complex processing, including identifying objects, recognizing faces, and understanding spatial relationships. These secondary visual areas are organized into two main streams: the dorsal stream, involved in processing spatial information and guiding actions ("where" or "how"), and the ventral stream, responsible for object recognition and identification ("what").