When the Brain Can't Make Its Own Maps
People with a rare neurological condition called Developmental Topographical Disorientation, or DTD, can even get lost inside their own houses.
Even though she hates lawn ornaments, Sharon Roseman, 68, has a grinning, pink lobster outside her home in Highlands Ranch, Colorado. She calls him Louie, and when she comes home, the lobster’s gaudy presence is the only thing that lets her know for sure that she’s made it to the right house.
Locating what should be a familiar landmark isn’t just hard for Roseman. Most of the time, it’s impossible. Roseman has a neurological condition called Developmental Topographical Disorientation, or DTD for short. She’s one in a relatively small population—there’s no official tally, though some researchers estimate 1 to 2 percent of people—of people who have extremely limited navigational skills and cannot form what scientists call “cognitive maps.”
Every morning when she wakes up, Roseman has to re-learn her way to her kitchen. When she can, she gets friends to drive her places; the rest of the time, she limits herself to destinations that require few turns, which sometimes means taking 30 minutes on a journey that would have otherwise taken 10. Dating was a nightmare, she said, because she could never tell potential boyfriends how to bring her home. And even though she had a successful career as an executive assistant before retiring in 2011, she could only take jobs that allowed her to commute entirely along straight roads (even curvature threw her off), and after-work happy hours at new bars were out of the question. Others with the condition say it’s like being a perpetual tourist in places that should be familiar. People with DTD can still theoretically understand verbal directions, read maps, and use GPS, though with difficulty; Roseman said that trying to understand GPS directions while driving is too overwhelming for her.
For years, Roseman did her best to navigate the world in silence, worried what people would think if she told them of her secret. When she was 29, her brother called her, sick, to ask for a ride to the hospital. On her way over, she got lost two blocks away from his apartment and eventually had to call him from a payphone for directions. Though he was able to direct her from his house to the hospital, her secret was out. After he had recovered, he pressed her to tell him and their other sister more about the condition she had kept hidden.
Soon after the hospital incident, Roseman’s siblings convinced her to seek help. It was the first time Roseman opened up to doctors about her inability to navigate, but it wasn’t her last. Though she sought both neurological and psychological help for her condition, no one could tell her what the problem was. Ten years after seeing her first neurologist without any luck, she tried another in Denver. When this doctor told Roseman she could have multiple-personality disorder, she became so upset she stopped looking for a diagnosis.
Then, in 2006, she happened to see a documentary about faceblindness, or prosopagnosia. The topic piqued her interest, and she did some more investigating online at faceblind.org, a website run by a researcher who was studying the condition. Out of curiosity, she took the site’s assessment on facial-recognition abilities, which included some questions about navigation. Her quiz answers alerted Brad Duchaine, a neuroscientist then at University College London (now at Dartmouth University) and one of the researchers who was running the site. He contacted Roseman directly, she said: “He sent me an email to tell me I wasn’t the only person who has this.” Though her symptoms fell outside his area of expertise, he promised to keep her case in mind and, and to introduce her to someone who was studying her condition as soon as he learned of the right person.
Duchaine stayed true to his word. In July of 2008, when he learned about the research of Giuseppe Iaria, a neuroscientist at the University of Calgary, he reached out to Roseman to ask if he could put them in touch. At that point, Iaria and his colleagues had just published a paper identifying the first recorded case of DTD.
Initially, Iaria had planned to focus his research on the variability of people’s navigational skills, or why some people are better at following maps and spatial directions than others. But in 2007, he met a woman who had come to the university’s neuropsychology department seeking help with a peculiar problem: Other than her constant disorientation, she was perfectly healthy, mentally and physically. After extensive testing, Iaria realized that she had something that hadn’t yet been documented anywhere. “She was something exceptional … She didn’t have any brain damage, she didn’t have any neurological conditions, or anything else other than getting lost in extremely familiar surroundings,” he said.
When they published their research in 2008, Iaria and his colleagues named the condition developmental topographical disorientation. “We call[ed] it ‘developmental’ because it’s not acquired,” he said. In other words, nothing happened to her brain to damage her ability to navigate; it was a skill she had never learned in the first place.
The condition presented a baffling problem. Structurally, the brains of DTD patients appear to be exactly the same as those of other healthy adults. But functionally, something is off: Different regions of the brain work well on their own, but may not work in sync the way they're supposed to.
Soon after Duchaine introduced Roseman and Iaria, the two began to exchange emails and talk on the phone. Roseman shared her stories with him about her experience. Roseman calls DTD “embarrassing, humiliating, scary, anxiety-provoking, [and] it gives me a headache because it’s so much to deal with at once,” she said. She described how, as a young mother, she could hear her children crying but couldn’t remember how to get to their rooms in her house; she just had to listen until she could figure out where they were.
The two kept in touch as Iaria and his team continued to study more patients with DTD to figure out why they were different. In 2014, they published a paper showing how they examined the brains of healthy individuals and patients with DTD using magnetic-resonance imaging, or MRI. (MRIs show oxygenated blood flow through brain regions, and indirectly indicate neural functioning.) The team monitored patients’ brains at rest, and found that in patients with DTD, the hippocampus and prefrontal cortex were not operating in sync, like the healthy controls’ brains were. Because the hippocampus and the prefrontal cortex are parts of the brain known to play a major role in spatial orientation, the researchers assumed that this desynchronization contributed to DTD patients’ inability to navigate.
“We’ve been focusing for many, many years … on what is the specific role of certain regions in the brain,” Iaria said. “The DTD [patients] tell you that it’s not just a specific region, but how all these regions are really integrated.”
In neuroscience, this concept is called “network theory”: the idea that connections between brain regions are just as important to functioning as the individual regions themselves. (Iaria believes that they matter even more.) Network theory emerged in the last 10 years or so, helped along, Iaria said, by advances in MRI technology that have made it possible to visualize the signals going back and forth between parts of the brain. Though it is newer than the more traditional concept of “locational functionality”—the idea that each region of the brain has a specific purpose— it’s beginning to gain acceptance in the field, and proponents of the network theory argue that the two ideas actually build upon each other. Arne Ekstrom, a cognitive neuroscientist at the University of California, Davis, compared the different ways of understanding the brain to auto mechanics: “There’s obviously value in understanding how a transmission of a car works … but if you want to see the whole picture, you need to take a perspective which allows you to see how these things interact with each other.”
To understand the connections the brain makes while forming and recalling cognitive maps, Ekstrom and his team are using a technique that tracks brain activity more directly than MRIs. In one study from 2012, they recruited patients with epilepsy whose brains had been hooked up to electrodes for seizure monitoring. (Because the procedure, which places the electrodes directly on the surface of the brain, is incredibly invasive, the team had to rely on people who were already undergoing it for other purposes.) The volunteers navigated through a virtual-reality world, and then tried to remember certain paths and the order in which they took them. As they did, Ekstrom and his team observed that many parts of the brain were active, including a part of the brain called the medial temporal lobe, where the hippocampus is located. This part of the brain acted as a connection between the prefrontal cortex and another part of the brain called the parietal cortex. “There are some brain areas that that seem to serve as hubs,” he said. Even though they may not be the signals’ final destination, hubs serve as their connection point.
According to Ekstrom, his research, like Iaria’s, suggests that in patients with DTD, the problem with forming cognitive maps stems from a disconnection between the brain’s information highways. “If you want to try to get to New York and you have to transfer through the country but Chicago is shut down, it’s going to be much harder to get there,” he said. Patients with DTD may eventually find where they need to be, using other tools like GPS or finding landmarks they know, but it takes them significantly longer than someone with normal navigational skills.
The network perspective of brain function may also explain why some people are better at understanding directions in general. When Iaria and his colleagues recently studied healthy patients to see if they could explain the variation in navigational ability, they found that patients with higher levels of connectivity among brain regions were better able to navigate through a virtual-reality world. “The more the network is integrated, the more robust the connections are, the more synchronized these regions are, the better the behavior is,” Iaria said. By understanding this kind of variance in healthy patients, they hope to understand how to help patients with extreme cases of desynchronization, like DTD.
At present, there is no cure for DTD, and while the cause still hasn’t been established, Iaria and his team are currently investigating whether it may be genetic. Roseman is grateful that her own children and grandchildren don’t show any signs of the condition, though she wonders if some of her mother’s behavior, such as never getting a drivers’ license and always making one of her children accompany her to the store, could have been because of undiagnosed DTD.
But even without a cure, Roseman feels that life has become a little easier since she met Iaria, who has connected her with others with the same condition. Together, she and Iaria created an online forum for others who have DTD called “Getting Lost,” where Roseman is one of the moderators; it’s both a source of information and a support group for patients, who often feel alienated because of the condition. “Having the ability to listen to other people who’ve struggled like you have, you definitely find a bond with them because you understand each other,” she said. “It’s an amazing way to make you feel less isolated.”