Neuroscience and navigating the city
And here’s the turn. Left. Through these doors. Around the bend and then left, right, right, left. Up the street with the funny looking trees. And ah, I’ve arrived. Whether we are walking through familiar bits of London or try to find the way home outside of our comfort zone, our brains are active in helping us.
Say you’re in the back of a black cab heading home from a meeting on the other side of London. You have a vague idea that you are somewhere between Hyde Park and Bethnal Green when the driver makes a sharp turn. But would you bother asking him what’s going through his mind as he weaves between the cars and declares he knows a short cut?
“In most research in psychology you focus on asking people to press buttons or for their responses so you can measure everything very carefully. You never ask people what they are thinking, that’s a no no,” says Hugo Spiers, lecturer in cognitive and perceptual brain science at UCL.
Spiers and his team wanted to link brain activity, with what we are thinking as we make decisions about navigating. To do this he not only needed to bring the streets of London inside an MRI machine, but he needed the best navigators in the city to face his task. He needed taxi drivers.
Getting taxi drivers inside MRI machines turned out to be more tricky then Spiers was expecting. Metal can’t go inside an MRI because the magnets inside these machines are incredibly strong. “I’d say have you got any metal in your body and they’d say no, no there’s nothing except the bullet in my back or my false leg or something else,” says Spiers.
Bringing the streets into an MRI machine also had a metallic challenge. Spiers used the Playstation game Getaway, which recreates London in detail as a simulation for the drivers to navigate. But the team had to spend months rebuilding a Playstation controller that the subjects could use from inside the MRI machine as normal controllers have metal parts.
While the taxi drivers were doing the simulation the researchers would change the destination enroute to make them think more. After the experiment they would question the drivers about what they were thinking during different stages of the course and link this to the brain images they had.
The researchers already knew the hippocampus region of the brain was important and this research confirmed it. It is a key brain structure that looks somewhat like a seahorse and is linked to both short and long term memory, as well as helping you navigate. But research by another team showed that taxi drivers actually have larger posterior hippocampi then other people. “That endless repetition of taking people around London that taxi drivers do here seems to drive this change, the longer they keep driving as a taxi driver the bigger their posterior hippocampus grows,” says Spiers.
They also tested normal people with a slightly different method where they made them navigate a simulation of the inter-winding streets of Soho. They found something surprising in both the taxi drivers and the ordinary people. Spiers thought the brain would track distances either by calculating a straight line between the person and their destination or by plotting the actual route. He found that the brain actually does both, first thinking about the distance as a straight line, before thinking about the specifics of the journey. “If you are heading home there is a link between you and home, independent of all the buildings and features,” said Spiers. They noticed no difference between male and females in their ability to navigate. But Spiers says women are more prone to using the layout of an area while men can tap into the geometry of space more effectively.
Ongoing research in this area is exploring the idea that researchers might be able to grow people’s hippocampi by making them do daily navigation tasks. Spiers said this might be useful for people with diseases like Alzheimer’s, who could be made to do daily tasks to keep their brains active. But if this even worked, Spiers said they did not know if this new ability would translate into all aspects of their lives or just making them better at navigating streets.
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