Extrastriate Mechanisms of Visuospatial Perception During Eye Movements

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PROJECT SUMMARY We move our eyes thousands of times each day, adding up to over an hour of our waking perception. These eye movements create considerable difficulties for the brain’s visual processing system, which must suppress the induced motion of the visual scene caused by the eye movement and provide a stable visual perception despite these discontinuities. How the visual system deals with the potentially disruptive consequences of our frequent eye movements is a question with direct relevance for our everyday visual perception, and especially to disorders in which eye movements are abnormal or the integration of information is impaired, such as schizophrenia, attention deficit hyperactivity disorder, and autism spectrum disorders; the integration of information across eye movements may be particularly important in reading, and potentially impaired in mental disorders such as dyslexia. Aim 1 of this proposal develops a novel statistical approach capable of producing an encoding model which captures the fast changes in neural sensitivity around the time of eye movements, and linking this activity to a perceptual readout. This approach reveals a novel neurophysiological phenomenon—persistent activity in response to stimuli appearing near the time of the saccade—which contributes to integrating the visual scene across saccades. In Aim 2, we apply the same modelling framework to the phenomenon of perceived changes in the location of visual stimuli around the time of saccades, and measure this phenomenon behaviorally in nonhuman primates. The impact of Frontal Eye Field (FEF) activity on the modulation of extrastriate neuronal responses during eye movements is causally tested using pharmacological manipulation in Aim 3. The combination of psychophysical, electrophysiological, computational, and causal manipulation techniques used in this proposal promises an unprecedented level of insight into how our brain actively reconstructs the visual world three times a second to provide us with a stable sense of the visual world during eye movements.