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The area of the visual cortex that receives the sensory input from the lateral geniculate nucleus is the primary visual cortex, also known as visual area 1 , Brodmann area 17, or the striate cortex. The extrastriate areas consist of visual areas 2, 3, 4, and 5 (also known as V2, V3, V4, and V5, or Brodmann area 18 and all Brodmann area 19 ).
Blobs are sections of primary visual cortex (V1) above and below layer IV where groups of neurons sensitive to color assemble in cylindrical shapes. They were first identified in 1979 by Margaret Wong-Riley in cats when she used a cytochrome oxidase stain, from which they get their name. [1]
The visual system is the physiological basis of visual perception (the ability to detect and process light).The system detects, transduces and interprets information concerning light within the visible range to construct an image and build a mental model of the surrounding environment.
A Brodmann area is a region of the cerebral cortex, in the human or other primate brain, defined by its cytoarchitecture, or histological structure and organization of cells. The concept was first introduced by the German anatomist Korbinian Brodmann in the early 20th century. Brodmann mapped the human brain based on the varied cellular ...
Orientation columns are located in the primary visual cortex also known as the striate cortex. These orientation columns are not cylindrical in shape as the word column implies but are flat slabs that are parallel to each other. The slabs are perpendicular to the surface of the visual cortex and are lined up similar to slices of bread.
The inner two layers, (1 and 2) are magnocellular cell (M cell) layers, while the outer four layers, (3,4,5 and 6), are parvocellular cell (P cell) layers. An additional set of neurons, known as the koniocellular cell (K cell) layers, are found ventral to each of the M cell and P cell layers.
Two main classes of cells in visual cortex were identified by David H. Hubel and Torsten Wiesel in 1962 through their investigation of the cat's primary visual cortex. [3] These classes were called simple and complex cells , which differ in how their receptive fields respond to light and dark stimuli .
For example, Hubel and Wiesel originally studied the retinotopic maps in the primary visual cortex using single-cell recording. Recently, however, imaging of the retinotopic map in the cortex and in sub-cortical areas, such as the lateral geniculate nucleus, have been improved using the fMRI technique.