Neurons in other cortical areas have complementary properties and are specialized to represent other information, such as the orientation of edges. Cortical areas also differ in the complexity of the sensory information they represent. For example, while some cortical areas contain neurons that respond well to any contour or edge, neurons in other areas respond only to more elaborate shapes or patterns. The responses of neurons within these specialized cortical areas are determined not only by inputs coming from the eyes but also by top-down influences related to attention. Neurophysiological studies from many laboratories have shown that the responses of individual neurons in the visual cortex of trained monkeys are affected by manipulating the animal's attention.
Neuronal responses are generally stronger when the animal pays attention to that stimulus.
Some of our recent experiments have been directed at understanding how attention affects the quality of sensory signals in the cerebral cortex. While it is known that attention makes sensory signals stronger, we are interested in learning whether attention makes neuronal responses more selective. Highly selective neurons, which respond only to a narrow range of stimuli, provide the most precise information about the visual scene. We examined whether attention to stimulus orientation affects orientation-selective neurons by restricting their responses to a narrower range of orientations. On some trials the monkey had to report the orientation of the grating, and on others it had to report the color of the other stimulus.