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Abstract

Vision is an active process, during which behaviourally relevant information is extracted from the visual environment and made available to guide actions. Understanding the neural underpinnings of visually based behaviour remains a key subject of investigation in systems neuroscience. One area of recent progress has been the documentation that the visual system does not remain static during adult life, but is instead subject to continuous experiencedependent modification and optimization involving neural plasticity at different levels of the visual system, as well as recurrent feedback among areas. The particular past experience of each individual thus shapes how incoming sensory signals are processed and analyzed. It has also become apparent that a comprehensive understanding of visual processing must include investigations of how visual areas interact with other brain regions such as parietal and frontal areas involved in controlling information flow through sensory areas and in generating plans or actions based on visual information. In this symposium, we present a multidisciplinary view of recent advances in our understanding of how visual signals are analyzed and used to guide behaviour. We will begin by focusing on neural mechanisms at the level of brain networks using functional imaging in human subjects, and on studies in humans of recovery of function after deprivation. Mark Greenlee will use fMRI to explore visual and eye-movement related signals during visual search focusing on effects on parietal and frontal brain areas. Alumit Ishai will examine the nature of object representation in human visual cortex using fMRI, and also the interaction between visual and fronto-parietal brain regions during imagery. Brigitte Roeder will explore how plasticity in the visual system can aid recovery of visual functions after sensory deprivation. The remaining presentations will focus on neural mechanisms at the level of single neurons using extracellular electrophysiological recording in awake behaving monkeys. Rufin Vogels will describe how learning changes the responses of neurons to visual stimuli in the monkey inferior temporal cortex, and will relate these changes.