The Incredible Human GPS

        Ever wonder how a cab driver is able to get you from point A to point “who knows where” without using GPS? Its cause his brain is bigger than yours… well… his hippocampus is. The hippocampus is a region in the brain important for long-term memory and spatial navigation. While it was long thought that talents were innate and had to be nurtured at a young age, researchers studying London cab drivers say that an old dog can learn new tricks. London cab drivers have to learn the layout of over 25, 000 streets through 3-4 years of schooling after which only 25% of aspiring cabbies make it out with a London cab certificate to attest to their ability to find their way through the city’s complexly interconnected web of streets. Through Magnetic Resonance Imaging, researchers have determined that London cab drivers have an increase in volume of the back part or posterior part of their hippocampus, indicating that the adult brain is still capable of changing its structure to meet certain demands. This means that talents are not necessarily innate but can also be acquired through repeated application. That’s right. Practice does make perfect.

        When compared to non-cab drivers or bus drivers, who follow a simple set route, cab drivers have a larger posterior hippocampus, which grows with years of cab driving experience, demonstrating that the posterior portion of the hippocampus is important for spatial representation of highly complex environments. However there is a catch. While the posterior portion of the hippocampus grows larger with driving experience, the anterior or frontal portion becomes smaller than those of bus drivers and non-cab drivers. This decrease in anterior hippocampal volume has been associated with a decrease in anterograde memory performance, that is, while cab drivers were better at spatial representation they were deficient in acquiring and retaining other new types of information such as directing movements in space as indicated by their lower performance in the Rey-Osterrieth test. This means that when cab drivers were shown a complex line figure and asked to draw it from memory, they were able to recall less than than bus drivers or non-cab drivers.

        Cab drivers don't only show that practice makes perfect, they also show that if you don't use it you lose it. Researchers compared the hippocampus of present cab drivers to retired cab drivers and found that the structural changes that occur in full-time taxi drivers are reversed in retired taxi drivers. Furthermore, retired taxi drivers scored less on their ability to navigate around London, however performed better in the Rey-Osterrieth test than full-time cab drivers.

        These observations are a testament to the fact that the adult human brain is not static but is quite dynamic, always adapting to our surrounding environment. This has implications in several fields such as education or rehabilitation of patients with cognitive impairments such as autism or even in Parkinson's disease. Researchers at UCL believe that with the right brain exercises we can strengthen those parts of the brain that are deficient or damaged. So those of you who claim to be "too old" to learn anything new, pick up that crossword puzzle, take that class you've been dying to take, start a new hobby and practice, practice, practice!

                         Michael Tibshirani

                          McGill University