The Plastic Brain of Taxi Drivers

What’s special about London taxi drivers? They have enlarged brains.

They’re not mutants. If you want to become a cabbie in London, you have to undergo a daunting test called The Knowledge. To pass, you must be able to plot the shortest route between any two of the city’s 25,000 streets, and point out any relevant landmark along the way (there are about 20,000 in all). Preparing for this mind-boggling endeavor takes three to four years, spent mostly driving around in a scooter with a map placed on the handlebars – remember that if you spot one in the city, it makes for a good story.

Fewer than 35 percent of applicants are granted a license, not surprisingly. What’s surprising is that London cabbies are responsible for disproving one of the longest-standing foundations of neuroscience: that the brain, unlike other organs, stops growing shortly after childhood and is incapable of spawning new neurons. A study conducted on 79 training cabbies had them undergo an MRI scan after three years of learning London topography. Their posterior hippocampus, an area of the brain involved with spatial navigation, was found to have acquired additional grey matter: it was, on average, 7 percent larger than before the training.

This phenomenon, the brain’s ability to rearrange itself and change its physical structure, is called neuroplasticity. It’s one of many reminders of how little we know about the human brain. Recent research from Sweden shows that this growth is linked to specific types of activity. This time, MRI scanners were used on interpreters learning a new language from scratch and comparing them to cognitive science students: while organs in the control group remained unchanged, over just three months the interpreters showed growth in the hippocampus (again) and in the cerebral cortex, which is quite understandably involved with language. This confirms previous research that revealed how bilingual children have superior brain functionality in some areas, and how being bilingual can delay the onset of degenerative brain diseases like Alzheimer’s.

It seems you can teach an old dog new tricks. But when it comes to the brain, not everything has a tangible effect. What about those Brain Training games, then? Nintendo and other companies maintain that by playing them regularly you can “keep your brain young”, citing dubious research. It’s a good marketing effort and by no means the worse kind of manipulation of science, but sadly it is not true. Christopher Chabris and Daniel Simons dismiss the issue in their brilliant book, The Invisible Gorilla: «If you think that doing Sudoku will keep your mind sharp and help you avoid misplacing your keys or forgetting to take your medicine, you’re likely succumbing to the illusion of potential. Unfortunately, people who do more crosswords decline mentally at the same rate as those who do fewer crosswords. Practice improves specific skills, not general abilities».

In other words, what you get by playing Brain Training is that you get better at Brain Training. But there is a very easy way to improve your mental abilities, and it’s got nothing to do with puzzles. It’s called exercise. Engaging in physical activity increases production of a protein that keeps nerve cells healthy, giving you better mental skills. This has been proven by different studies on humans and rats, as you can read in this New York Times article, opened by a very odd illustration.

For both rodents and men, walking or running for just a few hours a week improves cognitive functions and, of course, physical fitness. And people who exercise actually have larger brains in later life. On the other hand, data reveals that sitting for more than three hours a day can shorten your life span by as much as two years. So, say goodbye to “Dr Kawashima” and get out of that chair. Your brain will be grateful.

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Don’t Quote Me on This


Play it again, Sam.
Elementary, my dear Watson.
Houston, we have a problem.
Beam me up, Scotty!

It’s rather easy. You know exactly where all those famous lines come from. Of course, they’re from Casablanca, Sherlock Holmes (pretty much any book, right?), Apollo 13 (both the mission AND the movie), and the classic Star Trek series.

Well, not really. All of those are misquotations. At no point in the movie Casablanca does Humphrey Bogart say “Play it again, Sam”. He does say this: “You played it for her, you can play it for me. … If she can stand to listen to it, I can. Play it.” The wrong quote sticks mostly because it’s the title of the 1972 homage film by Woody Allen. Sherlock Holmes never utters the phrase “Elementary, my dear Watson!” in any of Arthur Conan Doyle’s books; the closest he gets to that is by saying “My dear Watson” and “Elementary” in two different lines of dialogue in the same page. And Jim Lovell, commander of the Apollo 13 mission, stated the following to mission control: “Houston, we’ve had a problem here. We’ve had a main B bus undervolt”. Pretty dull. But in the movie, Tom Hanks misquotes it in the fashion that we all know. And finally, Captain James T. Kirk never pronounces the words “Beam me up, Scotty!” in any episode of Star Trek. He does, though, repeatedly say “Beam me aboard,” “Beam us up home,” or “Two to beam up” and other variations thereof. Yet James Doohan, the actor who played Scotty, titled his 1996 memoir precisely Beam me up, Scotty!

There are many more blatant examples. Wikiquote has a handy list that saves me a lot of work. It’s easy enough to see why this happens. For an idea to stick, it has to be concise, simple, and strong. Beam me up, Scotty! is an immortal line, Beam me aboard is just a request. The You played it for her… speech might work in a movie, but it’s no T-shirt material. The interesting thing is that people become absolutely convinced that these quotes are correct, to the point that most will swear to remember them, in their exact form, from the source material. It’s one of the many tricks that our memory plays on us.

This is a very common practice anyway. You might have heard of the recent case of the New Yorker journalist who resigned after evidence emerged that a number of Bob Dylan quotes in his bestselling book about creativity were completely made up. To no one’s surprise, the media do that every day. It’s more than enough to catch the gist of what someone said if it needs to be put in a fancier, stickier form. There is an ongoing battle on the subject, with the New York Times on the forefront of media outlets that forbid quote approval.

But I digress. Here’s what I thought was, until five minutes ago, my favorite misquotation of them all. For years I have been reading a line attributed to Bugs Bunny, the cartoon hare famous for walking off cliffs in a straight line, unhindered by gravity: “I know this defies the law of gravity, but you see, I never studied law“. Too perfect, too clever, I thought. Conveniently made up, for sure. But see for yourself. Bugs Bunny’s PR representatives are the best in the business.