Multiregional Neuronal Computations Underlying Rapid and Flexible Visual Categorical Decisions

Summary and Relevance of Proposed Research Humans have a remarkable capacity to learn to recognize and make decisions about incoming visual stimuli. This ability, which is disrupted by brain-based diseases and conditions such as Alzheimer’s disease, schizophrenia, stroke, and attention deficit disorder, is critical because it allows us to learn about the meaning of the stimuli that we encounter, and it enables us to make appropriate decisions. The neuronal computations which underlie rapid and flexible visually-based decisions involve interactions among neuronal populations both within and between brain regions spanning visual, cognitive, and motor areas. To understand how coordinated neuronal activity mediated decision related neuronal computations, this project employs a close interaction between experimental and theoretical modeling approaches. The experimental work employs large- scale neuronal population recording techniques to monitor the activity in three interconnected brain regions— posterior parietal cortex (PPC), frontal eye field (FEF), and superior colliculus (SC)—during visual decision making tasks. Experiments also employ reversible inactivation of each brain region to causally test hypotheses. The theoretical work develops novel theories of neuronal population function directly inspired by the experimental data and inactivation results, in order to determine the patterns of neuronal activity and interactions within and between regions which support computations underlying task performance. While much is known about how the brain processes visual features (such as color, orientation, and direction of motion), less is known about how the brain learns and represents the meaning, or category, of stimuli. A greater understanding of visual categorization is critical for addressing many brain diseases and conditions (e.g. stroke, Alzheimer’s disease, attention deficit disorder, schizophrenia, and stroke) that leave patients impaired in everyday tasks that require visual learning, recognition and/or evaluating and responding appropriately to sensory information. The long-term goal of this project is to guide the next generation of treatments for these brain-based diseases and disorders by helping to develop a detailed understanding of the brain mechanisms that underlie learning, memory and recognition. These studies also have relevance for understanding and addressing learning disabilities, such as attention deficit disorder and dyslexia, which affect a substantial fraction of school age children and young adults. Thus, a detailed understanding of the basic brain mechanisms of categorical decisions and attention will likely give important insights into the causes and potential treatments for disorders involving these cognitive and perceptual abilities.