Orientation columns

In general with other sensory cortex, the main visual cortex is divided into radial columns 30–100 µm across. In each of these, all the cells respond preferentially to linear features with a given orientation therefore they are known as orientation columns. The cortex is organized therefore adjacent columns have an orientation preference which differs by only about 150; in another words, the orientation is represented in a systematic manner across the cortex. Columns that have similar orientation are arranged in stripes across the cortex. The obvious inference, that orientation selectivity is how the visual system signifies straight line segments that can be built up to give the form of an image, require not be true. The computer modeling illustrates that orientation selectivity is a property of neural networks which learn the curvature of curved surfaces from their shading. Therefore orientation selectivity may, counter intuitively, be concerned with the representations of curves instead of linear features in the visual world.