Fifteen years ago, a study showed that the brains of London cab drivers had an enlargement in the hippocampus, a brain area associated with navigation. But questions remained: Did the experience of navigating London’s complex system of streets change their brains, or did only the people with larger hippocampi succeed in becoming cab drivers?

Now, Carnegie Mellon University scientists have determined that learning detailed navigation information causes the hippocampal brain changes. Published in NeuroImage, Tim Keller and Marcel Just show that brief navigation training changes a person’s brain tissue and improves how that changed tissue communicates with other brain areas involved with navigation. The findings establish a critical link between structural and functional brain alterations that happen during spatial learning. They also illustrate that the changes are related to how neural activity synchronizes – or communicates – between the hippocampus and other regions that are important for navigation understanding and learning…

…Said Keller…”Our findings provide a better understanding of what causes the hippocampal changes and how they are related to communication across a network of areas involved in learning and representing cognitive maps of the world around us.”

To examine how the hippocampus changes, Keller and Just recruited 28 young adults with little experience playing action video games. For 45 minutes, the participants played a driving simulation game. One group practiced maneuvering along the same route 20 times. The control group drove for the same amount of time, but along 20 different routes. Before and after each training session, each participant’s brain was scanned using diffusion-weighted imaging which measures water molecule movement in the brain, and functional magnetic resonance imaging which analyzes brain activity.

The researchers found that the group that practiced the same route over and over — the spatial learning group — increased their speed at completing the driving task more than the group practicing on different routes, indicating that they learned something specific about the spatial layout of the virtual environment. The spatial learning group also improved their ability to order a sequence of random pictures taken along the route and to draw a 2-D map representing the route…

“The new discovery is that microscopic changes in the hippocampus are accompanied by rapid changes in the way the structure communicates with the rest of the brain,” said Just…”We’re excited that these results show what re-wiring as a result of learning might refer to. We now know, at least for this type of spatial learning, which area changes its structure and how it changes its communication with the rest of the brain.”

I had an acquaintance who spend decades as a cabby in Boston – another cluster of cowpaths and village-linking-footpaths that became an urban network. Though not on the scale of London. Upon retiring, he embarked on a methodical round-the-world tour that took two years.

I wonder if there’s an additional connection between the persistence of use extending beyond economic need?