Spatial Representations and Attention

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Several studies that combine behavioral methods with anatomical data in neurological patients have complimented evidence for two very general processing streams through the cortex, one involved in spatial processing (occipital-parietal) and the other in the perception and recognition of objects and their features (occipital-temporal). However, our preliminary work using chronometric measures reveals that despite the nearly complete loss of spatial abilities with relatively large bilateral dorsal lesions, spatial maps existed intact below the level of spatial awareness. These findings evolved from other preliminary work showing that bilateral occipital-parietal damage in humans affects how features are bound (presumably through ventral /dorsal interactions), suggesting a larger role for dorsal spatial functioning in object perception than previously recognized. When extensive loss of spatial awareness occurs, as with bilateral damage to the dorsal stream, shape perception remains but binding shape to surface features such as color, size or motion is severely disrupted. The proper binding of features appears to require explicit spatial knowledge that relies on dorsal systems. Although implicit spatial information remains intact, proper binding appears to require explicit awareness. The evidence is consistent with multiple spatial maps. Two sets of proposed studies are designed to explore targeted regions that may disrupt implicit spatial information and to determine the relationship of bilateral dorsal damage to unilateral damage that often produce other spatial deficits such as seen with unilateral inattention or hemineglect. Other sets of studies are designed to begin to explore the cognitive operations that contribute to implicit spatial effects observed in neuropsychological syndromes. The studies should help to determine the impact of cortical damage and underlying mechanisms that remain intact, potentially aiding in rehabilitation efforts and patient management. The translational potential of the work adds to the proposal's strength.