Updating location information across object and eye movements

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DESCRIPTION (provided by applicant): Effective interaction with our visual world requires us to represent both the identities and locations of objects, and to maintain this information as the objects themselves move, and as our eyes move over the objects. Directing attention toward a behaviorally relevant location facilitates the processing of objects in that location. But what happens if the eyes move while a location is facilitated? With each eye movement, the retinotopic (eye-centered) coordinates of the attended location change while the spatiotopic (world-centered) coordinates remain stable. A set of preliminary experiments revealed that facilitation temporarily remains at the previously relevant retinotopic location, even when the task requires updating to spatiotopic coordinates and the retinotopic location should have been invalidated by the intervening saccade (Golomb et al, 2008). This "retinotopic attentional trace" has been demonstrated for low-level spatial attention and discrimination of simple stimuli across saccades, but does it generalize to sustained representations of complex objects and actions? Aim 1 explores the generality of retinotopic attentional traces in a series of psychophysical experiments that manipulate the type of attention, nature of the coordinate frame shift, and mode of interaction with the stimuli. Aim 2 explores the neural basis of these effects with fMRI using (1) multivariate pattern analysis to determine how different visual areas express basic location information, (2) an ROI- based analysis to explore how representations of attended locations are updated following a saccade, and (3) repetition attenuation to ask how these representations are influenced by top-down demands when object location and/or identity is emphasized. These explorations of the scope, effects, and neural basis of the retinotopic attentional trace should help illuminate the nature of location coding in the visual system and the mechanisms by which the visual system updates location information as eyes and objects move. PUBLIC HEALTH RELEVANCE: Consistent with the NEI mission, this proposal aims to advance basic research in understanding the mechanisms of normal visual function. This research has implications for how the visual system functions in disease in addition to health: a variety of clinical conditions result in deficits at all stages of visual processing addressed by this research, affecting an individual's ability to locate important information in a cluttered scene, to perceive and recognize objects, and to integrate information across eye movements. To apply these findings to clinical populations, however, the basic research outlined in the proposal is necessary to more fully understand how visual locations are updated across object and eye movements in normally functioning adults