A PROCESSING STREAM IN MAMMALIAN VISUAL-CORTEX NEURONS FOR NON-FOURIER RESPONSES

Mammalian striate and circumstriate cortical neurons have long been un derstood as coding spatially localized retinal luminance variations, p roviding a basis for computing motion, stereopsis, and contours from t he retinal image. However, such perceptual attributes do not always co rrespond to the retinal luminance variations in natural vision. Record ings from area 17 and 18 neurons of the cat revealed a specialized non linear processing stream that responds to stimulus attributes that hav e no corresponding luminance variations. This nonlinear stream acts in parallel to the conventional luminance processing of single cortical neurons. The two streams were consistent in their preference for orien tation and direction of motion but distinct in processing spatial vari ations of the stimulus attributes.