Developmental Topographical Disorientation (DTD): A review

Topographical orientation is a complex cognitive ability defined as the capacity to orient and navigate successfully through familiar and unfamiliar environments. It is believed to involve different cognitive processes such as attention, memory, perception, decision making, mental imagery and all these cognitive functions are required to be preserved in order to recognize, use and integrate salient environmental landmarks and information to explore space and to reach a predefined destination in the complex environment of everyday life. Usually, difficulties in these abilities occur after brain damage; brain lesion studies have indeed confirmed the complexity of the human navigational system, highlighting that patients who suffer from damage to different brain areas showed also different types of topographical difficulties. However, recent evidence has highlighted a newly discovered condition called "Developmental Topographical Disorientation (DTD)" in which subjects seemed to suffer from a lifelong navigational deficit without any congenital, acquired brain damage or neurological diseases. Patients typically report severe difficulties to orient themselves in unfamiliar and even in familiar environments without any other cognitive complaints. This literature review aims to systematically summarize and compare neuropsychological, behavioral and neuroimaging evidence of the DTD single-cases reported until now, considering also findings reported by the group-study performed by Iaria et al., 2014. Generally, DD subjects showed a substantially preserved general intelligence but, in spite of that, they revealed different patterns of cognitive, spatial and navigational impairments so that some authors have already forwarded the idea of the existence of different DTD subtypes. Similarly, neuroimaging studies have evidenced different patterns of anomalous or lacking activations in different areas of the navigational network (such as hippocampus, parahippocampal place area, medial temporal lobe, prefrontal cortex, cuneus and precuneus and retrosplenial cortex) and also different aberrant functional connectivity between them was discovered. According to that, we aim to review and critically discuss the taxonomies which have been taken into consideration from previous authors in order to differentiate different subtypes of DTD patients. Suggestion for future studies will be also provided.