This post is also available in Dutch.
Have you ever felt lost in your own house? Chances are that you haven’t… unless you have a rare condition now known as Developmental Topographical Disorientation (DTD).
Every day you take pretty much the same route to work or university. And no matter how you choose to travel (by foot, bike, car), you are able to get from one familiar place to another with little effort or thinking involved. It is more likely that you are thinking about something else (an upcoming meeting or a friend’s birthday party) than a particular turn you have to make at each moment.
This is because your brain has formed a cognitive map, an internal representation of the places you navigate in. This cognitive map makes it possible for you to visualize where specific objects are in relation to one another and to yourself. If I asked you to close your eyes and picture a route from your home to the nearest supermarket, I am sure you could do this in a split second.
Navigation, among other skills such as recognizing faces, is essential for daily activities. Most of the time you are unware of and take for granted your automatic ability to orient yourself in familiar places. Imagine now that you completely lacked navigational skills. You would find it very difficult, if not impossible, to get anywhere. Getting from the living room to the kitchen to make a cup of tea would be quite a challenge for you.
Some people indeed can get lost in their own kitchens. These people are never able to form cognitive maps – they have a condition called Developmental Topographical Disorientation. DTD (in short) was first described only about 10 years ago. Developmental means that it is a life-long condition that starts in childhood. In spite of being mentally and physically healthy, those with DTD suffer from constant disorientation in both familiar and novel environments. But how is the daily routine of people who are perpetual tourists, even in their own homes?
People with DTD live in constant disorientation. Every time a person with DTD wants to get somewhere, they either need to memorize a sequence of turns or rely on GPS. This is quite time-consuming and very inconvenient, to say the least. For a person with DTD even a previously taken route is a “new route”. One might have spent years living in the same neighborhood and still be unable to orient oneself in it.
What’s different about the brains of people with DTD?
What is remarkable though is that the brains of people with DTD and those who have normal navigation skills do not differ structurally. The problem of poor navigation lies in how different brain areas like the hippocampus and prefrontal cortex, both of which are involved in helping to find one’s way around, “chat” with each other.
While there is still a lot to be discovered about DTD, one thing is clear – the way different brain areas communicate is as important as the individual regions themselves. But perhaps one of the most important lessons that conditions such as DTD can teach us is that something so central to our daily functioning as getting around, which may seem very simple (at first glance), is not so simple after all.