9309393 Allman One of the many mysteries of human perception is that after seeing random contours linked together just a few times, observers cannot help but see them as a whole, even when they are later unlinked. These illusory contours have been called "cognitive" contours because they exist only in the mind, not in the stimulus. With this new three year grant from NSF, Dr. Allman will investigate the neural basis of this phenomenon. In pilot work, he has found that animals develop the ability to see these cognitive contours as rapidly as humans. He has thus created a completely novel paradigm for the study of perceptual learning. He will now record in visual cortex to search for the actual neuronal changes that occur during the formation of the perceptual illusion. He will thus be able to describe the neurobiological correlates of a perceptual phenomenon, making this a first attempt to describe events at the mind/brain interface. ***