A fundamental fact of vision is that our perception of the external world is shaped by a number of behavioral and contextual factors. These factors include visual selective attention, in which sensory information is filtered in favor of items that are behaviorally and contextually relevant. In addition, it includes the modulation of visual processing during saccadic eye movements which occur several times each second. These factors are known to modulate the processing of visual information and to contribute to adaptive visually guided behavior. In the primate brain, the visual and oculomotor systems are highly interconnected, and past work has shown that movement-related signals exert robust influences on visual processing in visual cortex. The current proposal focuses on addressing key questions concerning the role of gaze control mechanisms in visual selection and visual stability, two ways in which those mechanisms clearly influence visual perception and cognition. These questions will be addressed using a broad set of innovative approaches and tools including newly developed, large-scale, high-density Neuropixels (NP) probes made specifically for use in nonhuman primates. In this first aim, we will test the role of persistent activity in the selection of visual signals and in visually guided saccades in a set of key, complementary experiments that include large-scale neurophysiological recordings with primate NP probes. Our hypothesis is that persistent activity in the frontal eye field (FEF) serves primarily to select the visual information required to guide saccadic eye movements, and that this function is mediated by dopamine D1Rs. In the second aim, we will address a major open question regarding the basis of stimulus-driven attention by testing the contribution of posterior parietal cortex (PPC) to the representation of visual salience in the brain, and to saliency-driven behavior. Experiments in this aim combine the use of reversible inactivation of PPC with large- scale neurophysiological recordings and behavior. In the third aim, we will address another major open question regarding the basis of the distortions in vision that occur during saccadic eye movements. We will leverage the use of large-scale recordings, and the use of reversible parietal inactivation to test the role of PPC in perisaccadic changes in visual processing within extrastriate visual cortex and the FEF. Overall, our focus on the influence of gaze control mechanisms on visual processing, combined with our use of state-of-the-art neurophysiological approaches and causal methods, are likely to produce results that exert a large and sustained impact on our understanding of the neural mechanisms of visual perception and cognition.
Results from the proposed work will have major implications for the neural basis and treatment of disorders of cognition, such as attention-deficit hyperactivity disorder (ADHD) which is one of the most common mental disorders affecting children, and which also afflicts adults. Thus the proposed research on the role the primate prefrontal and parietal cortex, and prefrontal dopamine, in attention and working-memory will have clear implications for mental health.
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