Functional anatomy of high-resolution visual mental imagery

This study had two purposes. First, in order to address the controversy reg arding activation of the primary visual area (PVA) during visual mental ima gery, regional cerebral blood flow (rCBF) was recorded while subjects perfo rmed a task that required high-resolution visual mental imagery. Second, in order to discover whether verbal descriptions can engage visual mechanisms during imagery in the same way as visual stimuli, subjects memorized 3D sc enes that were visually presented or were based on a verbal description. Co mparison of the results from the imagery conditions to a non-imagery baseli ne condition revealed no activation in PVA for imagery based on a verbal de scription and a significant decrease of rCBF in this region fur imagery bas ed on visual learning. The pattern of activation in other regions was very similar in the two conditions,, including parietal, midbrain, cerebellar, p refrontal, left insular, and right inferior temporal regions. These results provide strong evidence that imagery based on verbal descriptions can recr uit regions known to be engaged in high-order visual processing.