Mental blocks: fMRI reveals top-down modulation of early visual cortex when obstacles interfere with grasp planning

► Slow event-related fMRI design isolates visuomotor planning network. ► Visual cortex encoding of obstacles is suppressed during grasp planning. ► Concurrent IPS activity suggests top-down parietal control of visual cortex activity. ► Suppressing obstacle representations provides for an efficient avoidance mechanism. ► Unifies understanding of PPC involvement in action planning and directing attention.