Unthinkable

by Helen Thomson

  Using this technique, O’Keefe discovered a type of cell that fired only when the animal was in a specific location. Each time the rat passed through this location—pop!—that cell would fire. A nearby cell seemed to care only about a different location. Pop! It would fire whenever the rat walked through that location. The next cell would respond only to another location, and so on. Pop, pop, pop! The combination of activity of many of these cells could tell you exactly where that rat was to within 5cm². O’Keefe named them place cells and showed how together they told the rest of the brain, “This is where I am in my environment right now.”5

  Over the next few decades, it was discovered that place cells don’t do this job alone. They receive input from three other kinds of cells in a nearby region called the entorhinal cortex. One type of cell is called a grid cell, and was discovered by May-Britt Moser and Edvard Moser, former husband-and-wife team, both born on remote islands on the outer west coast of Norway.

  The Mosers realized that our ability to navigate partly relies on us being able to think about how we are moving and where we have come from. Consider the way you head to the ticket machine in a parking lot, and then reverse the movements of your body to return to your car. The Mosers discovered that grid cells were the neurons responsible for integrating this information into our cognitive map.6

  To understand how grid cells work, imagine running around a carpet that is covered in a grid of interlocking hexagons, a bit like a beehive. One grid cell will fire whenever you reach the corners of any hexagon in that grid. Shift the grid along ever so slightly to another section of the carpet, and another grid cell will be responsible for firing every time you reach the corners of that grid’s hexagons—and so on. These cells establish a generic map of space, giving you constantly updated information about your position and the relative distance between certain landmarks.

  The entorhinal cortex is also home to border cells. These cells give you information about where you are in relation to certain walls and boundaries. One might only fire, say, when there’s a wall that is close by to the south. Another might fire when you’re midway between two walls, or when you’re near the edge of a cliff.

  To complete the picture, border cells also share their real estate with head direction cells, which, as the name implies, fire only when an animal’s face is turned in a specific direction.

  The most widely accepted theory of how we find our way around the world is that our brain stores patterns of how place cells fire in a specific location, so that they can act as a guide for when we return to that location. Imagine looking for your car after a long day’s shopping, for instance. Your place cells crackle away, influenced by the direction of your head, the movement of your body and the landscape around you. They guide you around until the current pattern of activity matches that of the stored pattern, and voilà!—you’ve found your car.

  That’s not the end of the story, however. Despite all this activity, our internal compass is incomplete. We’re still missing a piece of the navigational puzzle—one so important that its loss can mean the difference between life and death.

  * * *

  When you find my body, please call my husband George and my daughter Kerry. It will be the greatest kindness for them to know that I am dead and where you found me—no matter how many years from now.

  WHEN SIXTY-SIX-YEAR-OLD Geraldine Largay stepped a short way off the Appalachian Trail to relieve herself, she never expected that she wouldn’t be able to find her way back. Known to her friends as Gerry, she was a retired air force nurse who had hiked other long trails near her home town in Tennessee. She had taken a course on how to traverse the entire Appalachian Trail, which runs over 2,200 miles and crosses fourteen states, and had completed more than 1,000 miles of the six-month journey.

  On July 22, 2013, Gerry tried to text her husband, who was waiting at a nearby checkpoint, ready to deliver her fresh supplies for the next leg of her trek. “In somm trouble,” it said. “Got off trail to go to br. Now lost. Can u call AMC to c if a trail maintainer can help me. Somewhere north of woods road. XOX.”

  Lack of signal meant the text never sent, so Gerry camped down for the night. The following day an official search began. For weeks they scoured the thick woodland to find her.

  In October 2015, a forester working for the U.S. Navy discovered a human skull with a sleeping bag around it. According to a report in the New York Times,7 a flattened tent lay a short distance away, along with a green rucksack containing Gerry’s possessions, neatly packed into ziplock bags. Nearby was a moss-covered notebook that said “George Please Read XOXO.” In the notebook Gerry explained that she had walked for two days after being unable to find her way back to the path. As she had been taught in her training, she set up camp in the hope that someone would find her. The last entry was dated August 18, 2013.

  While it is impossible to say what Gerry could have done to avoid this tragic fate, her disorientation was no doubt aggravated by the fact that she left the path at one of its most rugged sections. She wouldn’t have had to walk far before she was surrounded by thick underbrush and identical fir trees packed so tightly it would have quickly become impossible to make out the trail. There was nothing that distinguished one direction from the other. In short, there were no landmarks.

  You might not think much of being able to remember that there’s a post box at the end of your street, or a bus stop outside your office, but in fact the ability to recognize and incorporate these permanent landmarks into your internal map of the world is incredibly important. We constantly fill our mental maps with things that are meaningful to us. Think about directing someone from the nearest station to your home. What features of the route would you use to keep them on track? I’d use my local art deco pub, a museum containing an overstuffed walrus, and a distinctive triangular hill under which victims of the plague are buried.

  Our ability to recognize familiar landmarks is so important that there’s a part of the brain that is dedicated to the task—it’s called the retrosplenial cortex and when it’s damaged, it leads to severe problems in navigating.

  WHEN WORKING CORRECTLY, our spatial memory is outstanding. But with the use of technology—GPS, satnav, mobile maps in the palm of our hand—could we all lose our ability to navigate? Calculators, after all, have caused many people to suffer a drop in their mental arithmetic skills. In a commentary in the journal Nature, Roger McKinlay, former president of the Royal Institute of Navigation, says that this might indeed be the case. “If we do not cherish them, our natural navigation abilities will deteriorate as we rely ever more on smart devices,”8 he said.

  Our natural navigational skills can indeed be blocked by technology. Studies have shown that people who follow GPS systems to get from one place to another find it more difficult to work out where they have been than people who use traditional paper maps. Like many of our brain’s talents, it’s a case of use it or lose it. In 2009, Maguire and her colleagues showed that London taxi drivers who had recently retired performed worse on navigation tests than drivers the same age who were still guiding passengers around the capital.9

  Whether our technological crutches will eventually erode our natural navigational skills is unclear. A much more pertinent problem comes from not noticing that your tech is taking you somewhere you don’t want to go. In 2013, an elderly Belgian woman set out on the thirty-eight-mile journey to her home in Brussels, but after mistakenly entering the wrong address in her GPS arrived in Zagreb, 901 miles and two days later. Some stories are more tragic. In 2015, on her way to the beach, a business woman was shot dead in Brazil after a navigational app made her take a road through a gang-controlled favela. Even the most technologically advanced navigational systems may know where they are, but they don’t always know the best way to go.

  So are we becoming dangerously deskilled? Putting your faith in your GPS rarely leads to such awful situations, and is unlikely to diminish your natural abilities completely, but it’s important to re
member that you carry around with you an internal map that is—for now—more powerful than the smartest GPS.

  * * *

  Sharon and I set off for lunch at a nearby restaurant. I offer to drive, but Sharon insists she knows the way and that it won’t be a problem. These were lines delivered with confidence. But should a woman who has difficulty finding her own kitchen really get behind the wheel?

  I’d been keeping a watchful eye on Sharon as she showed me around her house. I don’t know what I was expecting—perhaps for her to look confused suddenly and then bump into a wall or something. But nothing out of the ordinary had happened, so I happily jump into the passenger seat.

  From her condo we drive around a couple of roundabouts, pass through a set of traffic lights and indicate left, then right without a hitch. We turn safely on to a small highway that runs through the town, the snow-topped foothills of the Rocky Mountains dominating the landscape to the west.

  Sharon points to the mountains and tells me that sometimes she’ll be driving into town when she suddenly realizes that the mountains are to the north and she’ll know that her world has flipped. Before I am able to process this statement she points to our restaurant. Then we fly past the entrance. “I can’t go in that way because it’s a big curved road,” she says, as if that’s a perfectly obvious explanation for our detour.

  As we park, I glance up at the mountains, so solid and unmoving. How could they suddenly face north?

  We sit down in Salsa Brava and order two iced teas. I ask Sharon to go back to basics.

  “Can you explain exactly what you see when your world flips?”

  She pauses for a moment, and then tells me to think about a busy shopping street in London. I choose Oxford Circus, with its heaving crowds and constant flow of human traffic.

  “Imagine you’ve had a busy day shopping,” she says. “You come out of the last shop and head left toward the station.”

  I picture the scene.

  “All of a sudden, though, you realize the station is actually on your right because you were in a shop on the opposite side of the street to where you thought you were. In that split second, you feel momentarily disoriented because the station that you thought should be east is now west. Your world hasn’t literally flipped but your perception of it has.”

  When that happens, most people’s brains are surprisingly forgiving. As soon as the brain gets confused, it spins everything around and it reorients itself—and you—within milliseconds. But that split second, in which your mental map doesn’t match with where things actually are, is how Sharon says she feels when her world is flipped. So when she says the mountains are suddenly to the north, it’s because her mental map has shifted them to the north, even though they haven’t physically moved an inch.

  “I just can’t flip my world back around like you can,” says Sharon. “Unless I do my Wonder Woman impression.”

  I ask why we had to take a detour into the restaurant. Sharon explains that curved roads make her world flip. It has made finding work difficult. In her mid-twenties she struggled to find a job. Every time she had an interview, she would have to work out in advance where the building was and whether it sat on a curved road. If there were a lot of winding passages in the building itself, she would have to turn down the job altogether.

  I want to know more about what Sharon’s alternate world looks like—was it not possible for her to recognize enough of her environment to work out which way to turn?

  “It’s hard to explain,” she says. “Think about standing in front of a bathroom cabinet with a mirrored door. Open that door and look at the rest of the room through it and you’ll know it’s your bathroom but everything’s kind of in the wrong place. Plus you’re stressed because everything looks different. It makes it hard.”

  When Sharon has to get up in the middle of the night to go to the toilet or if she’s in a rush in the morning and doesn’t have time to do her Wonder Woman impression, she says she feels like she is in a whole other condo. When she had young kids, she would have to follow their cries to find their room if they woke her suddenly in the night.

  “When it happens at home, I’ll know I’m in my kitchen but I can’t tell you what’s contained in any of the cabinets or drawers because I don’t have any attachment to them. I have to say to myself, ‘Okay, pretend you’re in your correct kitchen,’ and I know when I need a spoon I go to the drawer to the right of the fridge. So I look at the fridge in this ‘other’ kitchen and I say to myself, ‘Okay, that’s where the spoons are.’”

  THROUGHOUT SCHOOL, SHARON CONTINUED to hide her problem from her friends and family. The seeds of condemnation planted by her mother at such a young age had clearly taken hold. I feel a wave of sympathy. Sharon is so likable—so friendly, funny and intelligent. I’m amazed she kept this to herself for so long.

  Sharon was almost thirty before her secret came out in the open. Her brother had phoned her asking to be taken to the hospital. He suffered from Crohn’s disease and was feeling unwell. Sharon rushed out of the house in a panic, got into the car and set off on the short journey to his house. But somewhere along the way, her world flipped and she got completely lost. She pulled into a gas station to use the phone.

  She called her brother. “I can’t find your house,” she said, and described the gas station.

  Her brother was confused. He said, “You’re two blocks away from me—how do you not know where you are?” After the two of them had returned from the hospital, her brother asked her what was going on.

  “It was so emotional for me, I could hardly say the words.”

  It was the first time Sharon had talked about her condition since she was five.

  “After I told him what my mother had said, he was so mad, but he understood why I hadn’t said anything. Our parents weren’t well—we didn’t have a normal childhood.”

  Sharon’s brother told his doctor about her condition, who set up a meeting with a neurologist. With appointments to go to, Sharon was forced to tell her now ex-husband everything. Up until that moment she had managed to hide it from him very successfully.

  “I did very little driving, and the places I drove to were only very close to my house,” she explains. “I had already routed them out on straight streets so I wouldn’t get lost.”

  My thoughts about her bumping into things weren’t completely off the mark. She told me that she had been terrified of not being able to take care of her children in an emergency. When she jumped out of bed to get to her children in the dark, she would almost always run into a wall. Her husband just thought she was clumsy.

  “I allowed him to think that rather than trying to explain. I just felt so stupid.”

  When Sharon finally admitted the truth after eight years of marriage, the only thing she remembers him saying was “Is that why you’re always asking me which direction we’re driving?”

  “He just didn’t seem interested.”

  SHARON’S NEUROLOGIST TOLD HER that since she’d had the problem for so many years, it sounded like she might have a benign tumor or epilepsy. In either case, he said, “We’ll put you in the hospital, do lots of tests and try to fix it.”

  True to his word, he organized a barrage of tests, looking for signs of strange brain activity that would suggest epilepsy or an anatomical lesion that might explain the loss of direction.

  “I just thought, please, God, let there be something there that they can fix,” says Sharon.

  But there was no epilepsy, no lesions. Sharon’s brain looked completely healthy.

  “They said I needed to see a psychiatrist—they thought I was crazy.” The diagnosis caused her to suffer a bout of severe depression.

  “I wanted to die,” she says. “I’d just had my hopes raised thinking that the doctors would find something that could be fixed.”

  Sharon saw a psychologist for more than a year, and although he helped her work through her depression, he was unable to fix her disorientation. He told her to keep checking
in with a neurologist every few years to see if the research community had discovered anything new. He said, “I truly believe that this is something happening in your brain that we just haven’t yet learned about.”

  It wasn’t until Sharon turned forty that she felt strong enough to follow his advice. She made an appointment to see a doctor at the hospital she was working in as an administrative assistant.

  But as soon as she sat down, she felt uncomfortable.

  “This doctor gets out her little pad and paper and asks me what was going on,” says Sharon. “I tried to tell her as simply as I could—that my world lifts up, turns around and sets back down and I’m totally lost. She looked at me like I’m telling her a made-up story. She asked me how I correct it and I told her I spin around and it fixes it. She said, ‘Let me see you do it.’”

  Sharon was taken by surprise. She had never spun in front of anyone before.

  She winces at the memory.

  “I swallowed my pride, stood up and closed my eyes. It was so embarrassing. I spun around in circles until I knew the world had flipped.”

  The doctor asked Sharon what she saw.

  “I said, ‘Well, I’m in a different room now. I know logically I’m not, but this doesn’t look like the same room as when I came in.’”

  Sharon spun around again and sat back down. The doctor put down her pen and pad and said, “Has anyone ever suggested the possibility that you have a multiple personality disorder?”

  Sharon was mortified.

  “I’d shared my story and felt like I was being told I was crazy again. I just couldn’t go through that again. I got my purse and left.”

  IT WAS ANOTHER DECADE before Sharon made any further attempt to understand what was wrong with her brain. A friend had read some books by the neurologist Oliver Sacks and recommended that Sharon write to him about her symptoms. He replied a few weeks later. Sacks began by apologizing that he had not heard of such a condition. But he said he was reminded of stories told to him by astronauts who said they had experienced times in space when everything “looked wrong,” upside down or at an angle. Their world would suddenly right itself, when some clue—often a tactile one—allowed their orientation to become reorganized. Sacks also told her that the problem of not recognizing familiar environments might be similar to another condition called prosopagnosia, in which people are unable to recognize familiar faces.