RAPID COMMUNICATION Neural Correlates of Topographic Mental Exploration: The Impact of Route versus Survey Perspective Learning

There are two major sources of information to builda topographic representation of an environment,namely actual navigation within the environment(route perspective) and map learning (survey perspec-tive). The aim of the present work was to use positronemission tomography (PET) to compare the neuralsubstrate of the topographic representation built fromthese two modes. One group of subjects performed amental exploration task in an environment learnedfrom actual navigation (mental navigation task). An-other group of subjects performed exploration in thesame environment learned from a map (mental maptask). A right hippocampal activation common to bothmental navigation and mental map tasks was evi-denced and may correspond the neural substrateof a “dual-perspective” representation. The parahip-pocampal gyrus was additionally activated bilaterallyduring mental navigation only. These results suggestthat the right hippocampus involvement would be suf-ficient when the representation incorporates essen-tially survey information while the bilateral parahip-pocampal gyrus would be involved when theenvironment incorporates route information and in-cludes “object” landmarks. The activation of a pariet-ofrontal network composed of the intraparietal sul-cus, the superior frontal sulcus, the middle frontalgyrus, and the pre-SMA was observed in common forboth mental navigation and mental map and is likelyto reflect the spatial mental imagery components ofthe tasks.