Imagine walking from your bedroom to the kitchen and suddenly not knowing which way to turn.For most of us, getting lost means taking a wrong turn in an unfamiliar city or briefly losing our bearings when our phone battery dies. A familiar landmark is usually enough to put us back on track.But for some people, that sense of direction has never worked in the usual way.They can recognize buildings and landmarks around them and have otherwise typical cognitive abilities, yet still become lost in places they have known for years. In severe cases, that can include their own home.The condition is known as developmental topographical disorientation, or DTD. Unlike navigation problems that can emerge after brain injury or neurological disease, DTD is lifelong and occurs without an acquired brain injury that would explain the difficulty.
The first case described using the term DTD was reported in 2009 by neuroscientist Giuseppe Iaria and colleagues at the University of British Columbia in Canada.The woman they studied had struggled with navigation throughout her life despite otherwise intact sensory and intellectual abilities. Tests in real and virtual environments pointed to a remarkably specific problem: she had difficulty constructing a mental representation of her surroundings – what researchers call a cognitive map.Brain imaging offered another clue. When she tried to form a cognitive map, brain regions involved in memory and spatial navigation did not show the typical pattern of activity seen in control participants performing the same task.A cognitive map doesn't mean seeing something like Google Maps inside your head. It is a mental representation of how different places relate to one another.You might know that your home is near a train station, that the supermarket is several streets beyond your home, and that the park lies in another direction. Those relationships allow you to find shortcuts, approach a familiar destination from a different direction, or recover after making a wrong turn.In some people with DTD, building this broader spatial representation appears to be particularly difficult.
