Understanding how different parts of the brain communicate is perhaps the most fundamental question of neuroscience because it is at the heart of understanding all brain functions and disorders. It is of clinical importance because numerous brain diseases - autism, schizophrenia, attention deficit disorder, and many others - are thought to be due to impaired communication among regions of the brain, and attention in particular is impaired in every major neurological disorder. Even though numerous studies have led to understanding of how single neurons respond to flashes of light or simplified visual objects like lines, relatively little work has been directed toward explicitly learning how groups of neurons communicate with each other, and how that communication enables attending to important information and filtering out distractions. The research described in this proposal seeks to reveal how different parts of the brain communicate to support visual perception. The central question addressed is how different parts of the brain communicate to help select the parts of the visual world that warrant focus, and ignore the parts of the world that are distracting. The specific research aims are designed to (1) reveal how communication between visual and prefrontal cortex modulates over time and how those interactions impact behavior (2) develop statistical approaches to optimize the ability to use stimulation to intervene between these brain regions, and (3) apply these methods with microstimulation in prefrontal cortex to modulate visual responses and, in turn, attentional mechanisms. Together, these aims will have important consequences for the understanding of attention, neuronal communication, and interventional approaches to manipulate the nervous system.