Persistent neural activity in frontal cortex may reflect spatially specific feedback signals that bias activity in early visual cortex in favor of top-down goals. Here, we tested one key aspect of this hypothesis by measuring cortical activity in human retinotopic areas along the dorsal and ventral visual processing streams while subjects maintained over long memory delays planned saccades to or away from visual targets. In general, our results support the hypothesis that activity persists in the specific parts of the retinotopic maps that represent the location of the saccade goal. Topographically specific activity persisted as early as V1 and persisted not only in dorsal but in ventral visual areas. Moreover, activity persisted during the memory delay when the visual target was only available via working memory, and therefore reflects top-down mechanisms. Finally, when the visual target and saccade goal were spatially disassociated, delay activity was enhanced at the retinotopic locations representing both the visual target and the saccade goal. We conclude that the effects of spatially specific top-down signals elicit corresponding activity in early retinotopic visual areas and along the dorsal and ventral visual streams. Such a gain enhancement might underlie the mechanisms that prioritize the locations of task relevant items in visual space.
Meeting abstract presented at VSS 2014