May 13, 2013 at 7:28 AM ET
We all get lost or disoriented once in a while, but for Sharon Roseman, being lost is a way of life. A little quirk in her brain makes it impossible to recognize landmarks and find her way around neighborhoods that should have become familiar long ago.
“I can literally see my house out the car window, but I have no clue that it’s my house,” Roseman told NBC’s Kristen Dahlgren.
Roseman, 64, suffers from developmental topographical disorientation, or DTD, a disorder that had flown under brain researchers’ radar until very recently. DTD was first described as a single case study in a paper published online in 2008 in the journal Neuropsychologia.
At the time, it was thought to be extremely rare, says the study’s lead author, Giuseppe Iaria, professor of cognitive neuroscience at the University of Calgary. But since then, Iaria has discovered nearly 1,000 other people with DTD and he thinks there may be a lot more. He currently estimates that about 2 percent of the population may be constantly coping with orientation and navigation problems caused by the disorder.
DTD is a profound and disabling deficit. Nothing, not even the layout of a house you’ve lived in for decades, ever becomes familiar. And for Roseman that has made life very trying.
When her kids would cry in the night, she would struggle to find her way to them.
“Where I thought I was going out the doorway of my bedroom there was now a wall — and I would bang right into it,” she says.
Scientists have long known that injuries to certain parts of the brain could compromise patients’ abilities to orient themselves and navigate around the world, but what was novel about DTD was its appearance very early in the life of a child who had no injuries. Even more perplexing was the absence of any other deficiencies in memory or intellectual ability.
Roseman remembers when it first became clear that she wasn’t like all the other kids. One day when she was 5 years old and standing in front of their home, Roseman asked her mom where they were. When her mom pointed out that they were in front of their home in the Chicago suburb of Maywood, Ill., Roseman said, “This doesn’t look like our house.”
She remembers her mother’s stunned response, “That’s when she pointed a finger in my face and she said, ‘Don’t tell anybody because they’ll say you’re a witch and they’ll burn you.’”
That was enough for the little girl. She didn’t speak about her problems for years, or even as a grown up. She never even told her ex-husband.
No one knows exactly what is going wrong in the brains of people with DTD. Brain scans have shown that everything seems to be in working order. No brain region is shriveled or atrophied, Iaria says.
Scientists do know something about how the brain collects mapping information when everything is working correctly.
Jeffery Taube, who has been studying how rats navigate, has discovered that the rodents appear to have an internal compass.
“I do mostly recordings of single neurons,” says Taube, a professor in the department of psychological and brain sciences at Dartmouth College.
“So we watch as the neurons fire based on direction. The rat’s — and probably people’s — brain cells fire like a compass. There is a neuron that fires any time the rat heads north and another that fires when the rat heads south-southeast. There’s a full population of neurons that are responsive to all directions and they are always updating.”
But construction of a map isn’t just about keeping track of location, Taube says. Our internal cartographer also keeps track of landmarks — like a school, or a big building, or an oddly painted house — and correlates those with the location data. When everything works right, our brain’s cartographer constructs a map that allows us to find our way around places we’ve been without having to constantly check a paper map or ask for directions.
Map construction involves several areas of the brain, Taube explains. “There’s a system that’s important for perceiving where you are, another for keeping track of where you are heading and another for keeping track of the distance you’ve moved. Any one of these without the others won’t do you any good.”
Iaria believes that all those systems are in working order in people with DTD, but they just aren’t communicating properly with one another. He’s currently studying families in which some members have DTD and others don’t, trying to discover whether there is a genetic cause for the disorder. He’s also looking into ways to teach brains disabled by DTD to make maps.
While Roseman hopes that scientists do one day find a cure, she’d be happy if people just had a better understanding of what she and others with DTD go through each day.
“I want to someday have a child in kindergarten or first grade to be able to say to the teacher, ‘This isn’t the room we’re always in, is it?’ and I want the teacher to know about it.”