Why Cab Drivers Have Better Hippocampi

Ok, so the title is a little ludicrous.  Cab drivers don't necessarily have better hippocampi.  However, there is evidence that they have better trained hippocampi, so to speak, which allow them to process spacial information in a more efficient manner than the average person.

The hippocampus is a structure in your brain that looks a bit like a couple of protruding fingers horizontal with the temporal lobes.  It's primary function has to do with memory, both consolidation and recall.  In my previous posts I've mentioned examples such as H.M. (Henry Molaison) and others like him who suffered from a deficit in the hippocampus.  But now I want to show how a brain structure can also become better at its function, not  just worse.

The hippocampus is here hi-lighted in blue.

This study originated in the ancient city of London.  Like most old cities, the roads don't form a grid pattern.  Instead they form curves and loops in a jumbled mess like a knotted ball of string.  Also, the streets are not numbered in sequential older like the modern cities of today.  The names are assigned from times long past which makes for some confusing navigating.

Yet a recent study found that the cab drivers of London have more developed hippocampi than those of the average person.   The first instinct was to say that people who have better spacial memory naturally would become taxi drivers.  In other words, a simple correlation could be responsible for the connection they observed.

But further testing allowed for a more definite picture.  The researchers took participants who were training to become taxi drivers in London. (The test to become a cab driver requires that you know 320 routes, 25000 streets, and 20000 landmarks.)  The measured the participants early in their training and found average hippocampi.  But after the participants earned their cab license, the researchers took a second measurement system.  Indeed, the hippocampi of the newly minted cab drivers were more developed, proving it was the training leading to causation of brain change and not just correlation.

Just looking at this map of London increases my respect
for the cab drivers who navigate it.

So next time you think that taxi driving is a brain-rotting job, remember that your cab driver probably has a bigger hippocampus than you do.