Free GMAT Practice Questions

Passage

It has been a dogma of science that the human brain cannot change after early childhood. However, two recent studies present compelling evidence of brain plasticity. The first study found that the volume of hippocampal gray matter – the part of the brain associated with spatial memory – was much higher in the taxi drivers of London than in the city's non-taxi-drivers. Taxi drivers in London need to remember a complex web of thousands of streets and they use this spatial memory each day; their spatial memory gets a more rigorous and regular workout than that of non-taxi-drivers and this, the study concluded, causes the increase in their hippocampal gray matter volume.

Some critics of the first study countered that preexisting high hippocampal gray matter volume could have disposed individuals to become taxi-drivers. The second study was conducted to investigate this possibility. This study was done on individuals who were preparing for the Knowledge, an examination that a trainee-driver must pass to obtain a taxi-driving license in London and that tests trainee-drivers on their memory of the detailed spatial layout of the huge city. Most trainee-drivers take about four years to prepare for the test and still only half of them manage to pass it. Brain scans were taken of a group of trainee-drivers at the beginning of their preparation and again four years later, after they had taken the test. It was found that among the trainee-drivers who passed the test, the hippocampal gray matter volume had increased over the four years while among the trainee-drivers who failed the test, no change had happened. The brain scans taken at the start of the preparation showed identical hippocampal gray matter volume in both groups. This study proved unambiguously that the higher hippocampal gray matter volume in taxi drivers of London is not preexisting and, therefore, is the result of regular exercise of spatial memory.

Adapted from a research paper by K. Woollett and E.A. Maguire