Michael N. Shadlen

shadlen@u.washington.edu
Professor, Department of Physiology and Biophysics and Core Staff, Regional Primate Research Center; Adjunct Associate Professor, Department of Neurology

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Cortical foundations of visual perception.
Our senses convert the world around us to representations in the brain. For vision alone, over 20 maps of visual space have been identified in each cerebral hemisphere. Somehow the activitiy in these maps gives rise to behavior. When this conversion is obligatory we call it a reflex. When the conversion is contigent on circumstances, history and context we call it complex behavior. The central focus of our lab is to elucidate the transformation of visual information from evidence in a sensory map to a perceptual judgment that motivates behavior.

We record neural activity from the cerebral cortex during performance of a visual discrimination. We have identified sites in the brain where the visual data are represented and sites critical to the expression of a perceptually guided behavior, such as the generation of eye movements. We try to get in between these areas by targeting neurons in cortical association areas that reveal a plan to enact a behavior, well before exection. Since this plan reflects an interpretation of the visual data, our neurophysiological recordings divulge the subject's visual perception or impression.

By combining electrophysiological, psychophysical and computational techniques we can begin to elucidate the neural circuitry required to render nonreflexive behavior from evidence in sensory maps. How do "planning" neurons neurons maintain a response determined by sensory input that came and went a second ago? Which inputs affect the plan and how are they selected? These are the secrets of cognition.