The retinotopy of visual spatial attention

We used high-field (3T) functional magnetic resonance imaging (fMRI) to lab el cortical activity due to visual spatial attention, relative to flattened cortical maps of the retinotopy and visual areas from the same human subje cts. In the main task, the visual stimulus remained constant, but covert vi sual spatial attention was varied in both location and load. In each of the extrastriate retinotopic areas, we found MR increases at the representatio ns of the attended target. Similar but smaller increases were found in V1. Decreased MR levels were found in the same cortical locations when attentio n was directed at retinotopically different locations. In and surrounding a rea MT+, MR increases were lateralized but not otherwise retinotopic. At th e representation of eccentricities central to that of the attended targets, prominent MR decreases occurred during spatial attention.