DESCRIPTION (provided by applicant): The ability to recognize visual objects is a crucial component of our everyday interaction with the environment. Therefore, revealing how object recognition is accomplished is essential for any complete theory for the brain, as well as for our understanding of mental health. Here we focus on early, top-down facilitation during recognition. Anatomical studies have shown that connections between cortical areas are often bi-directional. Nevertheless, the majority of the research related to visual object recognition has concentrated on bottom-up analysis, where the visual input is processed in a cascade of cortical regions that analyze increasingly complex information. By combining imaging methods with complementary strengths to achieve superior spatio-temporal resolution, our preliminary results indicate that early top-down processing may provide a major facilitation during recognition. This facilitation may explain how visual object recognition, a faculty that is far from being realized artificially, can be accomplished strikingly fast in the cortex. We aim to characterize the mechanisms subserving top-down facilitation in object recognition by testing several specific hypotheses. The studies conducted under Specific Aim 1 represent the crucial first stage of localizing the top-down effects in the spatial and temporal domains. The studies that are proposed under Specific Aim 2 should help reveal the mechanisms that trigger the top-down processes, as well as the factors that modulate the magnitude of this facilitation. The results may have the potential of transforming the way we think about the flow of information in the cortex and, subsequently, of shifting the focus of the neurological, cognitive, physiological and computational research of visual object representation and recognition. Finally, object recognition is believed to be mediated primarily by the visual ventral pathway, with recognition itself being accomplished by the inferior temporal cortex. This proposed effort would help expose the role of the prefrontal cortex in visual object recognition, and elucidate the cortical basis for naming-related neurological deficits in patients with anomia and different types of aphasia.