British cabbies’ brains (hippocampi) change as routes learned

The brain structure of drivers hoping to be cabbies in London seems to change as they learn the complicated routes around the city needed to qualify as licensed taxi drivers.

In the capital city, those training to be taxi drivers must pass a test of the complex layout of the city’s 25,000 streets within 10 kilometres of Charing Cross train station as well as the location of thousands of places of interest. It takes London taxi driver trainees an average of three to four years to master the thousands of streets and their idiosyncratic layout in the city.It takes London taxi driver trainees an average of three to four years to master the thousands of streets and their idiosyncratic layout in the city. Luke MacGregor/Reuters

It takes drivers an average of three to four years to master the material, known as “the Knowledge.” About half of candidates pass the exam to get a licence to operate a taxi.

In Friday’s online issue of the journal Current Biology, British researchers found trainees who qualified as taxi drivers had greater volume of grey matter in the brain’s posterior hippocampus in MRIs compared with before they started the training. Processing of spatial information takes place in that area of the brain.

The study included 79 trainee taxi drivers and 31 non-taxi drivers who acted as controls. All of the participants were scanned before they took the test.

“By following the trainee taxi drivers over time as they acquired — or fail to acquire — the Knowledge, a uniquely challenging spatial memory task, we have seen directly and within individuals how the structure of the hippocampus can change with external stimulation,” said study author Professor Eleanor Maguire from University College London.

“This offers encouragement for adults who want to learn new skills later in life.”

No changes were seen in trainees who failed to qualify, or in the non-taxi driver controls.

But the finding needs to be tempered with another result from Macguire’s team. While taxi drivers showed better memory for London-based information, they showed poorer learning and memory on other memory tasks involving visual information, which suggests there might be a price to pay for acquiring the Knowledge.

The hippocampus is one of the few brain areas where the birth of new nerve cells is known to take place in adults.

It remains less clear whether those who succeeded at becoming taxi drivers had some advantage over those who did not.

“Could it be that those who qualified are genetically predisposed towards having a more adaptable, ‘plastic’ hippocampus?” Maguire asked.

The perennial question of ‘nature versus nurture’ is still open, the study’s authors concluded.

“Only a few studies have shown direct evidence for plasticity in the adult human brain related to vital functions such as memory, so this new work makes an important contribution to this field of research,” commented Dr. John Williams, head of neuroscience and mental health at the Wellcome Trust, which funded the research.


About Tore Nielsen

Researcher at University of Montreal and Director of Dream & Nightmare Laboratory
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