FIGURE 1.

Real-space navigation testing in patients with bilateral vestibulopathy. (a) Navigation paradigm in real space. The area, in which five target items had been placed, was shown to the individuals first on an investigator-guided walk (exploration, left side). Afterwards, individuals had to find the items in a defined pseudo-randomised order over the next 10 min beginning from the starting point (red square). The first five routes in the navigation paradigm were identical to the previous exploration routes and therefore had to be simply retraced (middle). Then, the order of target items was changed in a way that required recombining novel routes (right side); (b) Individuals wore a gaze-monitoring head camera to allow posthoc analysis of their visual exploration; c) [18F]-FDG was injected at the start of the 10-min navigation phase to depict the cerebral glucose utilization during navigation; (d) The normalized error rate during the navigation is depicted for the total paradigm, as well as separately for retraced familiar and recombined novel routes. (e) During navigation, BVP patients had a decrease of rCGM in the right hippocampal formation and bilateral insular cortex, and an increase of rCGM in the bilateral parahippocampus and lingual gyrus (i.e., parahippocampal place are, PPA) compared to healthy controls. BVP, bilateral vestibulopathy. Figure adapted from [4].