The representation of the retina becomes fairly complex in the cortex. The unfolded striate cortex has a shape like a pear. The far periphery, almost 90 degrees out, is so underrepresented that the half circle corresponding to 90 degrees, at the extreme right in the figure, is very small. Colors show the stimulus orientation which best activates each region of the cortex. Note that the preferred orientation changes smoothly with position everywhere, except at singularities, where a single complete set of colors meets.
Foveal representation is to the right.
The ice-cube odel of the cortex. A detail from a combined orientation and direction preference map Colours code for orientation preference and arrows show direction preference. This collateral system is thought to interconnect cells in different cortical columns with similar functional properties. The axon of one pyramidal cell, in the center of the diagram, synapses on other pyramidal cells in the immediate vicinity as well as pyramidal cells some distance away. The axon makes connections only with cells with the same functional specificity.