Influence of Familiar Distal Landmarks on Goal Representation: A Functional Magnetic Resonance Imaging Study.

Humans can perceive their relative position to the goal according to distal landmark cues (DLCs), which are cues situated in the distance and beyond the navigation scope. Specifically, familiar DLCs can facilitate the accuracy of spatial representations in human navigation. It is still unclear how human brain infers the distance and direction deviation to the goal through familiar DLCs. To address this question, we invited 26 young healthy adults to learn the locations of eight objects in a virtual reality arena with DLCs. We used two metrics: Euclidean distance (ED) for measuring distance and minimal angle (MA) for measuring direction. We then tested their direction and distance memory in the previous arena with familiar DLCs during fMRI scanning and in a different arena with unfamiliar DLCs. We performed a moderation analysis, which showed that the DLCs' familiarity moderated the influence of the ED to the goals (EDg) on end point location error evaluated by the ED (EDe). A univariate analysis on the task-fMRI data showed that the right SMA was related to the modulation of DLCs' familiarity on the relationship between EDg and EDe. Multivariate analyses on the fMRI data showed that the parahippocampal gyrus and retrosplenial cortex represented EDg in the direction memory retrieval, whereas thalamus and OFC represented both EDg and MA deviation from the goal (MAg) in the distance memory retrieval. These results provide insights into the neural mechanisms for the enhancement of DLCs in encoding relative position from the goal in spatial navigation.