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 it wasn’t clear if the experience of navigating London’s complex system of streets change their brains, or only people with larger hippocampi succeed in becoming cab drivers. Classic cause of correlation vs. causation.
To answer the question, scientists studied 28 adults who learned to play a simulation driving video game for 45 minutes. 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. The scientists scanned their brains before and after each training session.
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.
The spatial learning group also improved their ability to order a sequence of random pictures taken along the route and to draw a 2D map representing the route.
Importantly, only the spatial learning group showed brain structural changes in a key spatial learning part of the hippocampus, the left posterior dentate gyrus. There also were increases in the synchronization of activity–or functional connectivity–between this region and other cortical areas in the network of brain regions responsible for spatial cognition.
And, the amount of the structural change was directly related to the amount of behavioral improvement each person showed on the task.
“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,” says Marcel Just, a psychology professor at Carnegie Mellon University. “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.”