Form-cue invariant motion processing in primate visual cortex.

The direction and rate at which an object moves are normally not correlated with the manifold physical cues (for example, brightness and texture) that enable it to be seen. As befits its goals, human perception of visual motion largely evades this diversity of cues for image form; direction and rate of motion are perceived (with few exceptions) in a fashion that does not depend on the physical characteristics of the object. The middle temporal visual area of the primate cerebral cortex contains many neurons that respond selectively to motion in a particular direction and is an integral part of the neural substrate for perception of motion. When stimulated with moving patterns characterized by one of three very diverse cues for form, many middle temporal neurons exhibited similar directional tuning. This lack of sensitivity for figural cue characteristics may allow the uniform perception of motion of objects having a broad spectrum of physical cues.