The occipital lobe is the primary center for visual processing. It’s located at the back of the brain, and although its the smallest lobe, it contains very specialized areas dedicated to receiving and processing visual input from the eyes, interpreting color, shape, motion, and depth; mapping visual space to understand where things are located, and sending visual information to other lobes for object recognition, movementent planning, and emotional association.
The Lateral Geniculate Body (Lateral Geniculate Nucleus, LGN) is located in the thalamus, and acts as a relay station between the retina and the the primary visual cortex. The LGN receives visual signals from the optic tract and organizes them into six layers: the first two are magnocellular (motion, depth, low detail), and the last four are parvocellular (color, fine detail). The LGN is important for gating and modulating visual input before it reaches the cortex.
The Primary Visual Cortex (V1) is located in the posterior occipital lobe, and is the first cortical area to receive input from the LGN. It is responsible for initial visual processing, such as edge detection, orientation, contrast, and spatial location. The V1 also organizes visual input in a retinotopic map, and damage to it can cause cortical blindness, even if all eyes and optic nerves are intact.
The Secondary Visual Cortex (V2) is located just outside the V1, and processes more complex features of visual input such asd contours, depth, and figure-ground segregation. The V2 integrates color, shape, and motion from the V1, and distributes information to specialized visual pathways: the Dorsal Stream (the “where” pathway) and the Ventral Stream (the “what” pathway).
Occipital Lobe
