In a recent article on CNN, it was mentioned that while GPS navigation is becoming quite “the” thing to have, London cabbies want none of it. GPS systems were just allowed into cabs earlier this year, but very few drivers have opted for them; they prefer to rely on their own memory rather than any device prone to glitches. There’s a good reason they should do exactly that.
Every one of London’s cabbies has to take the grueling test known as “The Knowledge” in order to get a taxi license. The test consists of learning 320 routes as well as the city’s many confusing streets, shortcuts, and alleys.
The test is so tough — it can take up 34 months of study, albeit part-time, to pass — that academic studies have shown part of the brain of successful applicants actually enlarges.
Scientists found London taxi drivers have a larger hippocampus, the part of the brain associated with navigation, than other people.
This blurb refers to a 2000 Maguire et al. study published in PNAS, entitled “Navigation-related structural change in the hippocampi of taxi drivers.” (More below the fold!)
Essentially, the researchers compared structural MRIs of London cabbies’ brains with the brains of controls. The cabbies (who all passed “The Knowledge” test) were assumed to have “extensive navigational experience” while the controls were not. Their findings indicated that the posterior hippocampi (thats plural for hippocampus!) of the cabbies were significantly larger than controls, while the anterior hippocampi region was larger in controls.
It is of note that a greater difference was seen in the left hemisphere hippocampus versus the right hemisphere. This can likely be attributed to the fact that only right-handed cabbies were tested, which indicates that their left hemisphere is dominant in handedness and perhaps spatial preference. (The cut-off part on the y-axis says “Hippocampal cross-sectional area”).
In addition, posterior hippocampal size correlated positively with the time spent as a cabbie, and anterior hippocampal size correlated negatively!
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These findings make sense when you consider that posterior hippocampus is thought to store information regarding spatial representation of an environment, and has been proven to expand in people who depend on this skill.
In humans, as in other animals, the posterior hippocampus seems to be preferentially involved when previously
learned spatial information is used, whereas the anterior hippocampal region may be more involved (in combination
with the posterior hippocampus) during the encoding of new environmental layouts.
This is a fascinating finding which substantiates a model, as well as illustrates the ability of the adult brain to remain plastic and adapt to complex environments. Hat tip to Darkman.