By Angela Hodges
Researchers have found that different parts of the brain sequentially light up in London taxi drivers as they navigate their way to destinations across London. As the type of thinking required for different parts of the journey change, so too does the area of the brain that is activated.
Delivering the Charles Darwin Award Lecture at the BA Festival of Science, Dr Hugo Spiers from University College London said that no-one before has looked at the brain moment by moment to associate what a taxi driver is thinking with their corresponding brain activity during navigation.
While London taxi drivers are known to have a larger area of the brain called the hippocampus compared to other people, until now it hasn't been clear what relevance this has to the specific thinking necessary to carry out a successful journey.
The hippocampus is a well-established brain area important for short term memory and navigation, and is an area best known for its impairment in Alzheimer's disease.
The researchers found that, perhaps surprisingly, the hippocampus was only active at the beginning of the journey when the route to the destination was being decided.
If a taxi driver needed to change routes during a journey, if for example the road was closed, a different area of the brain called the prefrontal cortex became active. As they neared the end of their journey, activity in a specific brain area called the medial prefrontal cortex slowly rose, suggesting that this area acts as a gauge indicating how near the final goal is.
The study looked at 120 male taxi drivers who were asked to navigate their way through the streets of London using the Sony Playstation2 virtual reality game "The Getaway". Their brains were simultaneously scanned using a technique called fMRI. This technique allows researchers to see which areas of the brain are active when a person is thinking.
The taxi drivers were later quizzed about what they were thinking as they were navigating.
Interestingly, not a single taxi driver in the study was found to plan their complete route in advance. Their first action was to think about direction. They then pointed the taxi in the right direction before thinking about how they were going to get there. They frequently insisted that "it's the car that plans the route".
Of course, taxi drivers don't only think about how they are going to get to their destination. According to the researchers, they frequently wonder about their clients during the journey. They worry whether they are happy with the route being taken and wonder about why they are going to the requested destination.
"The areas of the brain that control these emotions are much harder to study," said Dr Spiers.