Selective map-following navigation deficit: A new case of developmental topographical disorientation.

INTRODUCTION: Developmental topographical disorientation (DTD) is a lifelong condition in which affected individuals are selectively impaired in navigating space. Although it seems that DTD is widespread in the population, only a few cases have been studied from both a behavioral and a neuroimaging point of view. Here, we report a new case of DTD, never described previously, of a young woman (C.F.) showing a specific deficit in translating allocentrically coded information into egocentrically guided navigation, in presence of spared ability of constructing such representations.

METHOD: A series of behavioral experiments was performed together with a resting-state functional magnetic resonance imaging (fMRI).

RESULTS: We demonstrated that C.F. was fully effective in learning and following routes and in building up cognitive maps as well as in recognizing landmarks. C.F.'s navigational skills, instead, dropped drastically in the map-following task when she was required to use a map to navigate in a novel environment. The rs-fMRI experiment demonstrated aberrant functional connectivity between regions within the default-mode network (DMN), and in particular between medial prefrontal cortex and posterior cingulate, medial parietal, and temporal cortices.

DISCUSSION: Our results would suggest that, at least in C.F., dysfunctional coactivation of core DMN regions would interfere with the ability to exploit cognitive maps for real-life navigation even when these maps can be correctly built.