Visual scenes and cortical neurons: what you see is what you get.

To even the casual observer, it cannot be doubted that animals are highly adapted to their environments. The long necks of giraffes help them to gather food from high in the trees and a cheetah’s speed helps it to capture prey. But over the last several years, studies of visual information processing have taken this sort of insight to levels that are not as inherently obvious. When we examine a visual scene, there are certain features that attract our attention, such as the face of a friend or an oncoming car. But to identify these objects, neural circuits in the visual system must extract relevant cues from the available visual information. For example, the outline of the oncoming car can be defined by the organization of oriented edges within the visual field. Information theory now is being used to define what cues are available within visual scenes. It is believed that neural circuits in the visual system should be adapted to take advantage of these cues (for review see refs. 1 and 2).