Cab drivers' grey matter enlarges and adapts to help them store a detailed
mental map of the city, according to research.
Taxi drivers given brain scans by scientists at University College London
had a larger hippocampus compared with other people. This part of the
brain is associated with navigation in birds and animals.
The scientists also found that part of the hippocampus grew larger as the
taxi drivers spent more time in the job.
"There seems to be a definite relationship between the navigating they do
as a taxi driver and the brain changes," said team leader Dr Eleanor
"The hippocampus has changed its structure to accommodate their huge
amount of navigating experience."
Taxi driver: No ordinary brain
Evidence that the brain is able to change physically according to the
way it is used could have important implications for people with brain
damage or brain diseases such as Parkinson's, she added.
"It has long been thought that if there's damage to the brain there's only
a limited amount of plasticity in an adult that can help them recover," Dr
"Now direct things in the environment, like navigation, appear to show
changes in the brain. So we could in the future see some rehabilitation
programmes that use that kind of knowledge."
The hippocampus is at the front of the brain and was examined in Magnetic
Resonance Imaging (MRI) scans on 16 drivers of London cabs. The drivers
had spent an average of two years in intensive training for "the
Knowledge" - the vast number of street names and routes in the capital
which they must learn to get their licence.
The tests found the only area of the taxi drivers' brains that was
different from the 50 other "control" subjects was the left and right
"One particular region of the hippocampus, the posterior or back, was
bigger in the taxi drivers," said Dr Maguire. "The front of the
hippocampus was smaller in the taxi drivers compared to the controls.
"This is very interesting because we now see there can be structural
changes in healthy human brains."
The posterior hippocampus was also more developed in taxi drivers who had
been in the career for 40 years than in those who had been driving for a
Dr Maguire's research is published in the US scientific journal,
Proceedings of the National Academy of Sciences.